Today, I give a shout-out to my son, Matt Simkins who was awarded a PhD in Computer Engineering from UCSC on Friday, November 8. Matt has an AS degree in Industrial Technology and a Baccalaureate in Mechatronics ( M.E. + E.E.). He was a Black-Belt in QA for 3 years as a practicing engineer. Matt’s been in school meeting intensive challenges for most of 20 years of his collegiate life. He was a college team bicycle racer in competitive road & mountain biking at UCD & Chico State University. His research extends into Neuroscience with studies of body motion related to the central nervous system in humans. Now, Matt intends to advance in academia as a researcher with a goal of becoming a professor, preferably at Stanford University. He’s designed several bicycle-related devices including his Egg Brake that is a lightweight, aerodynamic brake for racing bikes. Dr. Simkins is not only a good son, academic, husband & father; he’s one of my best friends!
Just an update: Dr. Simkins is now a tenure-track Engineering & Science Professor at Chico State University, a reprise of sorts to his Alma mater. He seems to be enjoying his old haunts!
A shoutout or shitup? What sort of crap will Americans believe next? Mechatronics and Buglanotics are only recognised by Chocolate Wild West University when accompanied with an Upstate Distribution Logolaurate Certificate. As Stanley is not a Wells Fargo Associate nor a Fellow of the Minnosota Institute of Technology (MIT) his NA (Not Applicable/North American) status is of no interest to those of us who have passed the P3 test (taken by people of age eight years and more) but can be used to confuse NA citizens who have little access to education systems which would give them the ability to differentiate between standard American "science" which still uses "inches", "fahrenheit" and "foot" to place people on "moon", and the remainder of humanity which has for decades been successful using the SI units to spread understanding and knowledge about the world in which we live.
computer stopped oh baby I think your clutch is slipping. You might want to go to direct drive but first set your engine down, I think it's overheating
Thanks. Its not easy inventing something practical that holds promise to improve efficiency of power transmission. What critics fail to appreciate is that this invention is the culmination of thousands of hours of research studying motor and engine dynamics as well as vehicle kinetics, not to mention thousands of dollars expense on prior prototypes & testing. The bicycle format is only a means of accessible testing, but the main purpose of this will be for engine & motor powered drive systems. This is a very serious endeavor with energy-saving goals. I've been itching to take this to the next stage when the economy justifies commercializing this invention. I appreciate your good will!
@@SIMKINETICS We appreciated your efforts but instead of publishing it either in form of patent or GPL which would lead to incremental improvements you kept it under wraps for 10 years that is unacceptable.
The problem is from people who "develop new" scams and when everybody realizes it was just a new take on an old scam all along, people become a little jaded and sceptical about any new development that isn't from a well known company. These scammers really penalize two groups of people: 1. Those who forked over cash and 2. Independent creators and developers, inventors and startups.
*Viewers:* Please read this comment & give it a thumbs-up to keep it on top to aid in dialogue. After considerable research, I've decided to use a heavy-duty #25 chain to raise input speed to the SIVAT. The SIVAT is a reducer, meaning its highest ratio is below 1:1, so raising its input speed (its sprocket) will compensate. Note that the overall 'gear ratio' on a bicycle must include the ratio of the front sprocket diameter to the rear sprocket diameter. By going from the standard bicycle chain pitch of 1/2" to 1/4" pitch, the rear sprocket diameter can be cut in half to increase the chain-drive ratio by a factor of 2 while keeping the front (crank) sprocket the same diameter. I've discussed this at length with a Tsubaki chain drive engineer (also an avid bicyclist), and he considered it very workable. The smaller chain actually has more working strength than typical derailleur chain, owing to greater width and cylindrical pins as opposed to barrel-shaped pins. The special sprocket sizes will likely be 95 teeth at the front, and 13 teeth at the back; giving the bike a high gear ratio that's equivalent to to a 48/11 combination which is the high standard for mountain bikes. Road bikes may use 105 teeth up front. High quality #25 chain is readily available, and I can include the sprockets & chain in the SIVAT kit so retrofitting the SIVAT should be fairly simple. Hard-tail bikes and full-suspension bikes with a unified rear triangle will be able to use a lightweight shroud to encapsulate & seal the entire drive system to keep lubrication in while keeping mud, dirt & rain out because the chain drive requires no derailleur or chain take-up idler with the SIVAT. I encourage viewer comments concerning this non-standard size chain/sprocket drive system. I've done this before on a very early prototype of a very different CVT, and did not notice any problem. Maybe other bicycling engineers or cyclists have some thoughts they'd like to share here.
+SIMKINETICS I think this guy is a con artist. 2008 and what still in prototype no new videos. Shit in 8 years a person could have a degree of their own and he can fuck off. I don't see any new videos? He talks about (The new design) where is that? I saw a video right before this video some jack ass turned out he has no prototype you are donating to his church. A lot of these piece of shit Religious people do that. Free energy/pie in the sky new technology. Often turns out to be a hoax you know a hoax because they leave out details or hide the area that would give away(The secret) they use things like this as a gauge for how dumb you are. If you will believe they have free energy shit you will believe anything. Like what's in the bible. A perfect target for Religion. Don't be a target tell this guy to produce a working product we can buy or admit it was just a con.
+Chris Tindall Lol con artist? What money or property did he con from you? What is he asking from you, just because someone has an idea and nothing has spawned from it or you don't see it in day to day life everywhere doesn't mean anyone is scamming or conning anything from anyone.... Wtf are you so salty about?
I just got a bike and would really like this upgrade, also hoping they finish and market them soon. Especially since his concept is so much more low-profile and ergonomic than the other one I saw so far researching 'automatic bicycle transmissions'.
Here's an update on the status of the SIVAT. I have potential funding for an initial prototype or two intended for testing on bicycles. This requires implementing a fully engineered design that fits goals for size, mass, power, efficiency & durability appropriate for bicycles; this is an extremely complex process of multiple calculation iterations to determine a balance of gear, bearing and structure sizes throughout. My initial goal of 1.0 kW power @ 90 rpm input appears to be too ambitious, so it will require rating the SIVAT for less torque at 90 rpm (optimal pedaling speed) input and commensurately lower power, but still within typical pedal-torque performance required by mountain-bikers. 1.0 kW throughput will likely be at higher input speed than 90 rpm. The intention is to provide a single core design that can be used on bicycles in various locations (hub, bottom-bracket & auxiliary), as well as on other small vehicles & machines. It now appears that my mind-numbing number-crunching is only in its early phase! Thanks to interested viewers whose patience I appreciate as not being 'infinitely-variable'!
***** Thanks! Yeah, a crowdfunding is most likely after the next video of a functional unit being used on a bike, fully engineered. I'm now in the process of thoroughly calculating its power throughput with updated design for real-world performance.
Only thing that's "mind-numbing" is it's stupidity and the suckers that think this is real. A classic example of 'bullshit beats brains' albeit very low intelligence brains.
Muranaman Mountain bikers would never go for the added weight, bulk, inefficiency and erratic operation of a VDP That's not an optimal drive system for any vehicle. Even a scooter deserves better!
Thanks! The featured proof-of-principle SIVAT did prove the principle, but was woefully inadequate for power throughput of bicyclists. Engineering this concept indicates a needed, very challenging change in much of the design to achieve product-level performance without growing excessively in size or mass. Now, I've got the tiger by the tail!
@Barnacules Nerdgasm I always mistake you for that tattooed magnetics&electricity guy. Who apparently has come up with some pretty groundbreaking ideas regarding how light magnetism and dielectric phenomena function in out realm.
@Game Plays 1230 Yes, as a general rule, the transmission should be in its highest gear ratio at launch & initial acceleration, and then lowering in its gear ratio to accommodate acceleration & higher speeds. This is precisely what the SIVAT does. My research & personal experience confirm that the most efficient & comfortable riding uses a transmission that keeps pedal-force and cadence fairly constant at all bike speeds; so that's what the SIVAT is conceived & designed to do automatically. A notable exception is the launch that has no prior force to urge it into its highest gear ratio, so I had to allow a 'lockout' of the automatic feature to keep the ratio high just for that launch from first pedaling. I first tried out this spring-reaction control on a predecessor prototype CVT many years ago, and discovered that it works extremely well on steep mountain roads as well as in flat rides, both ascending & descending. I'm convinced that this torque responsive control is the best way to control any CVT, and so is the automotive industry!
Thanks yourself! As an avid cyclist for decades, I've always tried to imagine the perfect bike transmission. As a mechanical engineer for decades, I've realized that it's possible. Inputs like yours help shape & refine what will be the outcome.
These concepts can be made at any size to power anything a bike a motorcycle a bus a train a city power grid and so on. You got yourself a great little transmission there. = )
wow that is awesome. I like how it can do zero ratio, that means you can eliminate the need for a clutch as you just keep it at zero while an engine is running then u just increase ratio very slowly , thus the unit performing the job of clutch. Love it.
Yeah awesome man, love it how the output can be stopped completely just by touching a finger on it, that's going to be really useful for all bike riders when they connect it to the wheel. I wonder why no funding has been given.
BTW, I believe that the SIVAT indeed has certain capability to become something like the "Holy Grail" of bicycle drivetrains, at least if the conception will be executed at the highest technical standards. So I’m curious to see and test ride a SIVAT in the not too distant future.
Your response changed my mind. Again I apologise for my ignorance and facetiousness. I hope you carry on with your interesting and important work and recieve the recognition and support you deserve.
Aaron Lowe Actually, the simplest version of this has an intrinsic 'hill-holder' feature; the driven wheel won't go backwards! I have to add a release mechanism to allow backward rotation. Regardless, biking up a 40 degree hill ain't gonna happen... 30 degrees is a boundary beyond which the rider will wheelie over backwards, which is the limiting angle used to determine maximum wheel torque I use for design overload. You might fall over sideways when you stop, but you won't roll backwards on any ascent without actuating the release device. The torque-limiting feature will ensure that users don't over-drive the unit with an accessory over-sized motor. This feature will not suddenly act, but will simply keep lowering the gear ratio gradually until it stops driving at all or until the overload is reduced. I've done a lot of mountain riding myself, so I know that any sudden disengagement would be maddening, and avoid that in my design.
Please see my response to DylanT, below. The SIVAT will be slightly less efficient than derailleur design in well-aligned (mid-position) sprocket pairs. I use planetary gear systems which have better efficiency than most other gearing types, about 99% each. I expect overall efficiency to be greater than 95% with the highest gear ratios' (for going up steep hills) lower efficiency skewing the average. Sprocket drives are the most efficient, but planetary gear drives aren't far behind. The SIVAT promises to improve pedaling efficiency of the rider that should more than compensate for power loss in the mechanism. After doing many calculations & subsequent design changes to balance component forces & speeds, I'm gaining confidence that this will be a product you'll see on bikes. Thanks.
I'm convinced that the SIVAT will push the evolution of transmissions in general! Having been an engineer for many years, I've seen & designed numerous drive systems for a variety of machines that would benefit from overload protection & ability to achieve a wide array of ratios with automatic or manual adjustment offered here.
Yes, you're right! The 'strength' of the spring does determine that. When the rider initially starts riding, the ratio will likely be in a high ratio, but will automatically lower within a portion of the pedal stroke; so he'll have higher wheel torque for initial acceleration. I'm choosing a spring that won't allow the ratio to go too low under any normal conditions, including steep ascents. The rider will be able to adjust the spring to his preferences.
I wish to all of you Merry Christmas, Happy Hanukkah & to all a happy holiday! May peace be the great fortune for you all without exception! Together, we can achieve universal peace & prosperity with nature & ourselves if we try.
What's the maximum output ration? You mention "infinity" in relation to the lowest ratio being 1:Zero. But what is "currently" the most output? 1:3.6 etc
James Fry Thank you for trying to help. Are you suggesting the IVT, reduces or increases rear cog input? ~ It sees you are referring to changing the size of the Crank gear : Axle gear. I would like to better understand the IVT itself.... It seems to be an infinite gear reducer....does that seem correct to you?
***** James is correct. The next generation prototype will include step-up gearing to raise the top ratio without depending on a large front sprocket for bicycles. The SIVAT will still work in the same manner, allowing a higher top ratio without affecting its ability to achieve very low ratios down to zero. This will enable use of a small front sprocket (30T to 36T) with excellent ground clearance.
A ratio of one to one is lousy for a bike to gain speed. You need at least three wheel revolutions to one full crank to achieve a reasonable amount of speed on a bike. Currently a ratio of 5 to 1 is needed to hit top speed on a bike.
Thanx. You're not alone. You & many others are the reason we'll be making the SIVAT into a product. My own disappointment with derailleurs led me on this long pursuit to offer something much better.
You should start a kickstarter campaign. Almost 4 million views and I just stumbled upon this today. It's a bummer this product isn't available yet. KICKSTARTER CAMPAIGN PLEASE! :)
Thank you. I used to be a hot rod, and knew quite a lot about high performance cars at the nuts-&-bolts level including the effects in competitive driving; I raced autocross. Be assured that that helps a great deal in M.E. Automotive transmissions are a target market for the SIVAT. Once proven on smaller vehicles, I'm sure that it will enhance performance in cars with scaled-up versions. The numbers indicate that it will likely be smaller than conventional units.
Indeed! They're on my checklist for design requirements for bikes with IC engines and electric motors, possibly up to 1kW (1.34 hp) of power capacity. Most of the core mechanism will work for pedal-power and motor-power with a single design for better economy-of-scale in production.
peter medz We might not offer a SIVAT for any specific e-bikes or gas bikes any time soon, but a kit for you to adapt to motor/engine power will follow its initial pedal-power marketing & sales.
I just want to congratulate you on two counts - firstly for doing this in the first place - and secondly for the patience and politeness you show in this column! I'm a lifetime ME and MTB-er (just to wind up the anti-acronym brigade!) following your progress with hope. An application jumped into my mind; hybrid cars use Rankin-cycle IC engines to get 15-20 pc fuel saving; a much wider range of vehicles could use this engine type, using your trans to stay within its smaller efficient rpm range.
godsthunder26 I'm redesigning the SIVAT. One goal is to provide a core that can be adapted to any bicycle with a minimum of special optional parts. You'll still need to pedal it unless you choose to motorize your bike; adapters will likely be offered for its motorized use too. Without leg or motor power, you won't go anywhere except downhill! Maximum power throughput will be 1kW, which is ~4X typical pedaling power for athletic MTB riders.
He has the end of the chain we don't see hooked to the pedals, powered by an external source. Like an electric motor. If u notice, the chain seams to turn at a constant rate after it's rotation is started. The lever he is moving is the linked to the variable output. So as the lever input changes, so does the speed of the output shaft. No matter the input shaft's speed unless, the input isn't turning. Don't divide by Zero, lol. His device is mounted on the wheel, or hub (back end) of the bike. The device can replace the transmission (ten speed, 15speed, etc) assembly with just one device on the rear hub. It has no power output within it. There is no motor inside, but a very neat device.
ptrainenator thx! so no more derailers and stuff like this ? impressive a more symetrical more agile bike ? perhaps ? lets see how it works and lets see the cost ?
ptrainenator Close! I actually turned the bike's crank by hand while keeping a constant pedaling rotation speed. The front sprocket is 55T, the back sprocket (the SIVAT 'input') is 11T; so the whole system has a 5X speed increase even before SIVAT affects it's own output. In the newer design, the gearing up is internalized w/ a 2.7X ratio so that the chainwheel can be as small as 32T for great MTB ground clearance & a very high top gear ratio. The bicyclist can choose his preferred front/back sprocket sizes without losing the ability to achieve all overall ratios down to zero!
I personally believe it to be a false claim (hoax). Especially the part at 5:17 where he says that the output will come to zero rpm in an 'overload' situation. Just thinking, how handy this would be (NOT), if this was on a car and you were going up a hill.
Thanx for your response. The problem with making a speed responsive bike transmission is that pedaling hard causes an upshift when you want a downshift! If you pedal forcefully in one ratio, the bike speeds up with that scheme, sending it into higher ratios. I figured that torque-responsive ratio change is better, and proved it decidedly riding with an earlier automatic CVT. The SIVAT will deliver what you're asking for without electronics. It's actually simple.
No video of it actually working on a bike? Probably slips when under the slightest payload. Show how effective it is. Put a wheel on your bike, ride it up on an extended incline, shoot and post the video. Talk is cheap. To see is to believe.
Talk is cheap, but prototypes are not. The next video will feature a working prototype for testing on a bike with mountain riding. Posting this concept video has garnered enough interest to justify costs to take the concept to the next level. This concept has no prior art from which to design a perfect initial device; it's a totally new idea. What was learned from this proof-of-principle unit was used to fully sort-out what's needed for a real-world mountain bike transmission in a second design. By showing this concept first, potential customers are offered the opportunity to help determine its viability in the marketplace. Both public interest and engineering calculations indicate that the SIVAT should move to the next level; a pre-production prototype that's fully capable of processing the physical power of highly athletic mountain bicyclists ascending the steepest mountains they can ride. As a seasoned mechanical engineer with decades of experience, I'm reluctant to waste anyone's money on a losing proposition or a planless approach devoid of adequate research. It takes more than one step to succeed with a new idea.
I'd suggest if there's not a prototype working on a bicycle then the project isn't serious enough. It has been 7 years since this video was posted. There's no disclosure of how it works (or view inside) so it can be seen only as a concept. Not that a cvt isn't a good idea for a bicycle but working prototypes are the real proof of the pudding. Even if it's an unconventional bicycle with the device outside the hub (perhaps a gear train going from crank to the device then another from device to rear hub). The model being shown isn't carrying any load so it's not very convincing. If there was a clear disclosure of the internals you'd be prone to get descent review and support and likely find someone to help. Do you have a Web site or something serious for this project showing the details?
+Darcy Whyte You'll be in for a surprise. I've recently re-started this project with the goal of building a working bicycle-mounted prototype for a demo in 2016. As for showing the insides, that would void the patent application(s); something I'd be foolish to do! This video admittedly is about a proof-of-concept, a starting point from which I anticipated finding design weaknesses that are not associated with the concept, but rather with its specific implementation of part sizing & potential re-design to correct its few initial design errors discovered in testing this unit. The basic theory is sound, and the re-designed prototype won't grow much in size or mass if at all. The demo will show an athletic bicyclist riding on hilly terrain, and some test results.
+SIMKINETICS Good on you. 'Smart, interesting video. As an everyday cyclist without a car, I'd love to have an automatic transmission on my bike, and I really hope you succeed. Questions... - Rough idea of likely price, if you can estimate it - Ideas about electric drive with a lithium ion battery - From a few years' experience of an Avanti Electra front-hub electric bicycle motor, a flywheel will produce very bad 'twist' effects at 90 degrees axis. I would discourage that, even for recovery of energy, and even on the back I guess. It also adds weight. And batteries are getting sufficiently capacious to obviate need for a flywheel. Bruce Thomson in New Zealand.
+Bruce Thomson Thanks! My goal is to get the price within the range of that CVT you sometimes find on bikes, a few hundred dollars as a kit or added as a standard component on some brands. The first units will likely be higher-priced to amortize some of the start-up costs, but eventually automated fabrication & assembly efficiencies can make them quite affordable because the design isn't more exotic or complex than 7 or 8-speed hubs. My engineering career involved much automation design, so I'm designing it from experience. The flexibility of wide-ranging variable gear-ratio choice enhanced by a microprocessor would help both battery life and motor dynamics on an e-bike. I've done fairly extensive research on that, and will do more before we get to that point. E-bikes may be a substantial market for the SIVAT. SIVAT power-density is high enough to make that quite practical up to about 1.0 kW throughput or more. The flywheel energy conservation scheme I referenced was never intended for certain small vehicles for the very reason you cite. However, I'm aware of methods to eliminate gyroscopic effects that make the scheme appropriate for vehicles that can handle the extra *weight!*
+TheLegoman0077 Thanks! Once I get the working prototype (next-gen) build on a bike, I'll ask for some volunteer testers to help evaluate the SIVAT. My personal tests on a somewhat related automatic prototype suggest that it will please even hard-core mountain bicyclists. My latest iteration will likely offer an optional fully-sealed version that will avoid contamination from the drive-sprocket/chain-drive system to the hub, and better ground clearance than current derailleur drives.
Thanks. FYI, IVT is a term for the special case of CVT's that have no bottom limit in ratios. That's explained in the Wikipedia article on CVT's. In effect, it references the IVT as uniquely being capable of approaching infinite input-to-output ratio. The big dogs already know this.
By convention, transmission ratios are output speed divided by input speed. The newer SIVAT ratios will vary between ~3:1 and 0:1 internally; the high limit is raised by the external sprocket ratio, so the 5:1 sprockets in the demo would provide a 15:1 final high gear ratio! Using a much less radical sprocket combo (like 34T front to 16T rear) would still get a higher top ratio than road bikes have.
Wait, so you could literally have the pedal be connected to that lever. when not pushed, there's no motion, and as you depress it the speed increases? This is incredible! it's literally a powered takeoff. This completely eliminates shifting gears, the only thing you need to change is the variable ratio as you drive. This would be perfect on a gocart, you could just have the engine run at normal rpm's. Has this become a product yet? If so, i'd love to just purchase one for experimentation.
+Akash Hegde Not! Those drives rely on *dynamic* friction that's dependent on losses. The SIVAT uses *static* friction. The difference between dynamic friction & static friction is most important as a metric in efficiency; the static version being nearly without loss! I do not want to throw away power & energy! Do you?
The SIVAT will provide pedaling resistance similar to modern derailleur systems, but will allow you to globally tune that resistance force by simply turning a knob that changes the thresholds for ratio change. The range of ratios will extend into both higher & lower ratios than is practical w/ derailleurs. The goal is to keep pedal resistance & cadence within a narrow range despite the grade of the hill you're ascending or descending; that optimizes pedaling efficiency.
This is idiocy. You can never have a gear ratio of 1:0. Anytime you have input speed, there has to be some output speed. Looks to me like you've put a clutch inside a case. Cool invention bro
Because he's afraid that the second he puts it on the shelf, someone will take it apart and share the plans of the internal workings... As easy as it was for him to cut it out on his CNC is as easy as it would be for someone else to do the same and shut it down. This is my opinion. Hope I'm wrong. Good luck.
That's an excellent comment. The answer, ironically, is in your YT name! I learned the hard way, in real estate transactions, that timing is very important for business start-ups and large money transactions. You must know about minimax principles. Commercializing a brand-new invention is not merely about demand, which is apparent; it's also about significant capitalization, sustained funding, supply-chain stability, distribution & ROI. Investment capital is tight now for a reason; the American economy has too much uncertainty, with global ramifications. When I see these economic risks in a sustainable downward trend, I'll get that ball rolling, likely with crowdfunding or similar. Regarding a patent or any disclosures, I have a strategy for timing that too. For security purposes, I won't discuss that.
SIMKINETICS well, I wish you luck, hope to see this soon, and hope it makes bike riding more efficient and enjoyable. You know with fuel prices and pollution we should all get around on bikes when possible.
When your gear ratio is too high, the rider will naturally use more pedaling force on any bike. The SIVAT ratio control mechanism is spring-loaded toward high ratios, while also being reactive towards lower ratios from pedaling torque. These opposing forces are in a state of equilibrium when the rider is pedaling within a narrow band of torque (force) regardless of the SIVAT's ratio; outside that narrow band, the ratio will change rapidly toward low, slowly toward high until new equilibrium.
I think one of these would be great to get me up Mountain Charlie road. I hope I hear about this as soon as it's commercially available in a bike. Thanks again for the directions. - David
Thanx! The seccond design is intended for hard use on MTB's & motor-powered bikes. It has a universal design which can be adapted for hub, bottom bracket or a separate location such as at a F.S. pivot for the rear suspension. A bottom bracket version would be ideal for weight distribution & would allow an un-idlered chain drive like a fixxie, but would require a special bottom bracket on a hardtail. Its very high top ratio will allow a very small chainring like a 32 or 34-tooth size.
That is precisely what the SIVAT is designed to do. When the grade of the hill levels off, it resumes toward higher gear ratios. Reviewing the mathematics involved in the geometry of its automatic shifting, it turns out that the shifting mechanism can be simple for regulating pedaling cadence & torque within narrow limits; the goal of efficient pedaling on mountain trails.
One of my goals for the 2nd design is to raise its power throughput to enable use w/ motors up to 1 kW. This isn't easy considering weight & size constraints for a bike, so this is taking more time than I expected. I've also considered the same design to be used as a bottom-bracket mounted version and a hub-mounted version so that most components are the same for both versions; this should ultimately give more flexibility for the end-user to arrange a motor-drive for mopeds either way.
I would love a transmission like this on a sports car with a manual configuration. A lever in the center console allowing you to adjust the ratio manually would be a real experience to drive. Unfortunately no car manufacturer would ever build such a machine.
On the prototype shown, the input is 5:1 (55T front sprocket, 11T rear). The second generation will have an internal high output-to-input of about 3:1, so it doesn't need such a radical sprocket setup on its external input.
Amazing Barry! While on the road for long distances I ever shifting gears to get up and down hills. on tips of 250 miles or more my hands can get very tired of shifting and holding the handle bars on conventional bicycles. so what ever it takes to modify a bicycle to make the ride more comfortable to increase endurance is a plus. Thanks for using your mind. I hope to see the future of this technology become commonplace
Thanx for your interest! I'm in the process of working out the complex details of licensing the SIVAT technology to a maker of products that can use it. After an agreement, we'll start developing it as a product. That will take many months before it's available to you. The SIVAT does not rely on traction like toroidals; it relies on gears for positive engagement. The Brazilian marketplace is likely an early recipient, so keep looking for it! It's a good choice for you!
I've been an engineer for 1/3 century, & I learned early on that it's far better to do research about a subject before critiquing it. Research is very easy with the internet; if you teach yourself how to dig up & discern fairly complete, relevant, accurate information, you'll be armed to quickly develop a defensible opinion. If you want to become an effective engineer without losing credibility amongst your peers, research is the first step. Engineering is dependent on information & facts.
barry even though I didn't get all of the tech stuff I do understand the principles behind this device. Very ingenious in design and well thought out for applications that will make bicycling a new a very exciting thing again. I for one appreciate the stuff people like you do for the rest of the masses that have limited resource to be able to not only put so much into the actual product development but also the reasoning behind why it would be such a big leap in technology for something so simple as a bicycle to move us around.
Have you thought about any practical design or designing for/with wind or hydro turbine/generation? I think this could revolutionize that foeld as well.
+Steve Frappier It looks like your comment was for me instead of brian noel, so I'll answer your question. Between my own ideas of how this transmission can be used *and* ideas suggested by viewers, we've come up with over two dozen practical uses, including wind & water turbine power. After doing extensive research into wind turbines, it appears that the SIVAT would help protect the expensive drive-systems from damage due to strong gusts, and would eliminate the need for some of the expensive control electronics that modulate power output AC frequencies. Generator input speed can be controlled by the SIVAT for constant speed & frequency operation, while air flow (or water flow for hydroelectric power) varies over a wide range at the impeller. Thanks for your question!
Thank you for answering, and so promptly. It's refreshing to finally see a thinker and doer after such a long time without. Your idea and its applications will, indeed, go far. Thank you for sharing. Best of luck to you, Sir! Steve Frappier
Thanx for digging a bit deeper! I want the SIVAT to be an excellent MTB transmission in every way. About 20 years ago, I co-founded a riding club, so have had the opportunity to observe what MTB riders need & want. These YT comments have been adding to that. BTW, we will be working on getting the mass down to a minimum without sacrificing durability & easy maintenance.
I'm a big guy who's destroyed the 3-speed hub repeatedly by bicycling in mountains with it combined w/ derailleur [hybrid] gearing. This experience taught me about what's needed to design a tough alternative that's lighter & stronger. I'll test the SIVAT for durability. It will compete w/ the remarkable Rohloff, & will likely beat it & the NuVinci in efficiency, longevity & weight. The patent is in-process, and it is unique as an invention.
I've looked into wind turbine applications intensely, & I agree with you. It's also obvious that the auto industry has a 'not-invented-here' attitude. We've deemed the bicycle market as an excellent entry point though because bicyclists are most open to technological advances, especially where that tech imbues their experience with a more intuitive feeling & better care-free performance. As an inventor, you'll surely appreciate that customers are king.
Thanx. The ratio-control mechanism won't be cumbersome because it works automatically. It shifts ratio according to your pedaling force, something very natural & non-distracting. I got the idea originally from those old Sturmey-Archer 3-speeds that you could pre-shift up & expect to actually shift by very briefly relieving pedal force; great for drag-racing on a bike! The SIVAT refines that experience.
Overload protection will be user adjustable within the power rating of the SIVAT, and is only included to prevent catastrophic failure in the event of abuse. It's occurance will be very rare,very subtle & easy to recover from.
The current design increases its intrinsic highest gear ratio to ~3X, so it's no longer a reducer only. This change enables use of a modest 36T/18T sprocket combo to achieve gear ratios higher than most bikes.
It can be controlled with a handlebar-mounted lever too. The main intended control method is the rider's pedal force which was proven to be very natural by a similar, earlier CVT. We'll test some variations to determine what control system riders prefer.
Thank you. Like you, I've done a lot of bike riding, preferring riding in mountains, and have experimented with modified gearing (for several decades) to accomodate getting my large body up & down steep hills. Shifting gears is often problematic & annoying even with today's refined derailleurs & hub gears. Riding with a predecessor auto-CVT, I discovered the surprisingly intuitive nature & efficiency of smooth auto-shifting; my goal here is to refine that for all types of riding & riders.
I built & used a CVT version of this on a bike. It worked very nicely on hilly rides, but didn't have the ratio range I wanted. This IVT version has more than enough range now. I've done a helluva lot of bicycling in mountains, and designed the SIVAT specifically to address pedaling efficiency, supported by research into bicycling ergonomics done by sports physicians, & by studies of elite bike racing pros. Consistent input (not output) cadence & force are the result.
Good question. I deliberately designed this to respond to overload far in excess of most bicyclists' power output. It's there to prevent abuse with over-sized motors exceeding 1.0 hp. An uphill start will be a positive drive at a fairly low ratio. The user can adjust this per his preferences within safe limits.
Derailleur systems vary between 92%-96% efficiency depending on sprocket/chain alignment, but only as well-lubed & clean. The SIVAT is estimated to be 87%-93% efficient, also dependent on ratio with very low ratios least efficient; that will be tested in development. Ratio range: 3X to 0.2X at hub; multiply these by your sprocket ratio for final over-all ratios. In theory, the lowest is zero, but only if it's over-torque at input (nearly impossible for bicyclists).
Notice that the drive chain converges toward the rear sprocket. The input is 55T/11T, or 5:1. Multiply the SIVAT ratio by 5! Regardless, the new design is ~3.6:1, making a very high top ratio with a smaller front sprocket.
Notice that the chain converges to the back sprocket. The front sprocket is 5X larger than the rear sprocket, so the actual gear ratio is 5X higher than what you see in the SIVAT alone. Regardless, the new design will include much higher ratios on its own.
You're forgiven! It would take hours to read all the comments. Torque-sensitive ratio control makes the most sense by far; I extensively tested my own auto-CVT predecessor in mountain riding, so I can assure you of that. Peak input torque automatically limited to ~100 Nm (an industry standard), & will be user adjustable on the unit. Peak output torque:~200 Nm. These values would accomodate world-class sprinters with their 'explosive' pedaling. A ratio lock lever will be included.
"Regardless, the newer design will have a ~3:1 internal hub high ratio, so even fairly small front sprockets will deliver high gears." Good to see you're still plugging away at this device Barry, can't wait to see the results. You should get onto Kickstarter so the peoples of the world can throw some funding at you =)
As one who's done a lot of mountain riding & shifting gears on both Road Bikes & MTB's for several decades, I sought a better way. Once you ride with this, you'll understand how well it responds to changing grades while leaving your MTB experience to focus on steering, braking & pedaling. I intend to make the experience of shifting w/ leg force a trouble-free, efficient, fluid & intuitive ride with more range than current MTB's.
Yes. 20-to-1 might be close to the practical limit of high gearing. The method to achieve that is to use step-up gearing at the input and/or output. The new design SIVAT has an internal high ratio of ~3-to-1, so you'd need to use 7X gearing. Note that the video version has 5-to-1 at input by using a 55T/11T sprocket combo, so the whole system has a high ratio of ~4-to-1. Very high ratio transmissions usually are less efficient in general.
Thanx. Yes, you'll be able to drive the hub directly if you use a large rear sprocket. 250 watts won't be a problem, but you might need to change the spring that controls the automatic shifting.
Yes, Mechanical Engineering student and master fabricator/tuner/engine builder for a racing group called Rebel Racing. I do tons of work with 3rd 4th and 5th generation GM vehicles, typically with big camshafts, and aftermarket torque converters to make up for their lack of low end torque. This would be an amazing unit if it could handle the abuse of 500-1000+ horsepower in cars, with an electronic controller to dictate stall speed. Good luck!
You're welcome. Getting one design into several uses will help bring the cost of production down. I've deliberately sized the 2nd design for power & physical size & shape to make it most universal for several likely applications like small motorized vehicles, conveyor drives, industrial machines & robots. Since I've designed some of such devices during my long career, I'm fairly familiar w/ those apps, as well as bicycles like MTB's.
Thanx! The new design will offer a 2.7X high gear ratio! That's big-time overdrive! Even disregarding the 55T/11T chain-drive ratio here for top gear on its chain-drive, The SIVAT will offer many options for input or output gearing at nearly all intermediate ratios!
Thanks. I now have a source for funding. But you're correct about Tesla; they once had a 2-speed transmission to improve efficiency, but abandoned it because their torquey motor broke gears on the shift from shock-loading. The SIVAT does not 'shift' with any disengagement/engagement cycle, so it should work well for their drive system. I've had them in my sights for later development.
The response has a fluid-like feel to your legs, very natural & intuitive. The ratio will lower to the extent of your pedal force; more force will cause the ratio to go lower, but only slightly more quickly, never abruptly. As the ratio changes downward, it will tend to equalize to cause your pedal cadence & force to remain nearly constant most of the time, regardless of grade. Upshifting will be quicker. You'll also be able to tune it for your personal preference & power level.
The SIVAT's ratcheting mechanism uses the same system that's used in most automatic transmissions in cars, so it's reliability has been very well proven, and is rarely the source of failure in those transmissions. The SIVAT's gear ratio has negligible effect on the speed or forces therein. It uses rolling sump lubrication common to all hub transmissions on bikes, so that's proven effective too. We'll conduct life-tests to find & solve any weaknesses before commercializing this as a product.
Yeah, this was brought up before. The intermittent motion you see goes away when the output provides some resistance. Without resistance, the very slight drag in the ratcheting mechanism dominates with a subtle erratic motion that quickly disappears under load. At very low ratios, this no-load irregularity is amplified, so you notice it only near the zero-speed condition.
For mopeds & pedelecs, the motor will be 'geared-down' to allow for the fact that motors generally run faster than pedaling. the newer SIVAT has lots of range & a higher high gear ratio to accommodate motors and/or pedaling on hilly rides.
Excellent question! You must be an M.E. or student, as such! The SIVAT does not use hydrostatics, but measurements of heat propagation of a related mechanism indicate that losses are low, likely ~ 6%-12%. This will be tested on the 2nd generation prototype in at least 2 ways: via thermal mass transformation over time, and by dynamometer tests at various ratios. I doubt that a lubricant cooler will be needed; rolling sump cooling should do the job for bikes & motorcycles. Thank you.
Yes. I tested a bike with a predecessor CVT with a similar automatic feature; and that's exactly what it did. This effect will be attenuated with an adjustable damper that slows the response in the half cycle of pedaling action. One unexpected benefit from some of this action (in the earlier CVT) was reduced stress on knees. The rider will have the choice about adjusting this for his/her preferences, but even light damping is not objectionable as I discovered in my undamped predecessor.
The BitRaptor is a variant on the Epicyclics CVT that's been around since the 80's. It's 2:1 bandwidth (ratio of high gear-to-low gear) has limited uses, unlike the SIVAT that has infinite bandwidth.
Yes. The SIVAT has an unlimited number of ratios available. You might consider it as a thousand-speed transmission. Also, its highest gear is higher than most, & its lowest gear is much lower than any, with all choices in between.
Thanx! It's good to know that others, like you, appreciate the advantages of constant force, constant cadence pedaling on variable grades. Scientific studies of bicycling dynamics show that maximum power & efficiency result from such regulation as a consequence of our physiology.
Current development is for a non-bike application, so the bike version won't be available for at least a year. The bike hub SIVAT will likely include 10mm & 20mm axle options. I'm also considering a bottom-bracket version for special F.S. frames to accomodate pedal and/or motorized MTB riding w/ very light rear wheels.
It's a completely different mechanism, and it does not 'slip'; it's always fully engaged without dynamic friction. A newer design has a higher top limit (2.7X) to its ratio range using a spring (instead of a rubber band) to adjust toward its upper limit unless throughput torque momentarily brings its ratio down proportionately. When torque decreases, the spring automatically raises the ratio.
Exactly! It means that you can be in the right gear so to speak, at all time. Also, as it is nearly fully enclosed, it can potentially be a lot more maintenance free, and you don't need to worry about chains falling off from time to time because it doesn't need to jump from gear to gear.
We're working that out now. A purpose-built SIVAT will be featured on specialty vehicles first, likely this year. After that, we'll productionize the design for mass-production in order to make it affordable for more popular applications like bicycles & mopeds.
I read what you write as your observation that the output looks irregular at super-low ratios; that irregularity disappears under typical operating loads. The second design won't drop to zero output under any real MTB bicycling forces. BTW, when it does go to zero, it appears to slip, but it does not slip; it's still fully engaged, and cannot roll backwards at the output. It helps to know that the SIVAT works in ways unlike transmissions with a clutch.
This is awesome! One of the things in my ever-growing "to-do list" was to make something for a bicycle that would provide a constant "force demand" for the rider (ie the transmission adjusting to the slope of the road)
This uses gears instead of rollers to transmit power, so its power capacity is significantly greater for its size. Although current CVT's in cars are limited in power thoughput, they've proven to enhance systemic efficiency which can apply to cars with greater power using this approach.
Today, I give a shout-out to my son, Matt Simkins who was awarded a PhD in Computer Engineering from UCSC on Friday, November 8. Matt has an AS degree in Industrial Technology and a Baccalaureate in Mechatronics ( M.E. + E.E.). He was a Black-Belt in QA for 3 years as a practicing engineer. Matt’s been in school meeting intensive challenges for most of 20 years of his collegiate life. He was a college team bicycle racer in competitive road & mountain biking at UCD & Chico State University. His research extends into Neuroscience with studies of body motion related to the central nervous system in humans. Now, Matt intends to advance in academia as a researcher with a goal of becoming a professor, preferably at Stanford University.
He’s designed several bicycle-related devices including his Egg Brake that is a lightweight, aerodynamic brake for racing bikes. Dr. Simkins is not only a good son, academic, husband & father; he’s one of my best friends!
Just an update: Dr. Simkins is now a tenure-track Engineering & Science Professor at Chico State University, a reprise of sorts to his Alma mater. He seems to be enjoying his old haunts!
SIMKINETICS fixed gear for life
***** haha your so gay!
A shoutout or shitup? What sort of crap will Americans believe next? Mechatronics and Buglanotics are only recognised by Chocolate Wild West University when accompanied with an Upstate Distribution Logolaurate Certificate. As Stanley is not a Wells Fargo Associate nor a Fellow of the Minnosota Institute of Technology (MIT) his NA (Not Applicable/North American) status is of no interest to those of us who have passed the P3 test (taken by people of age eight years and more) but can be used to confuse NA citizens who have little access to education systems which would give them the ability to differentiate between standard American "science" which still uses "inches", "fahrenheit" and "foot" to place people on "moon", and the remainder of humanity which has for decades been successful using the SI units to spread understanding and knowledge about the world in which we live.
computer stopped oh baby I think your clutch is slipping. You might want to go to direct drive but first set your engine down, I think it's overheating
sad that so many comments appear so rude - development of ideas should be explored in a civil manner - thank you for the video - very intertesting
Thanks. Its not easy inventing something practical that holds promise to improve efficiency of power transmission. What critics fail to appreciate is that this invention is the culmination of thousands of hours of research studying motor and engine dynamics as well as vehicle kinetics, not to mention thousands of dollars expense on prior prototypes & testing. The bicycle format is only a means of accessible testing, but the main purpose of this will be for engine & motor powered drive systems. This is a very serious endeavor with energy-saving goals. I've been itching to take this to the next stage when the economy justifies commercializing this invention. I appreciate your good will!
@@SIMKINETICS We appreciated your efforts but instead of publishing it either in form of patent or GPL which would lead to incremental improvements you kept it under wraps for 10 years that is unacceptable.
The problem is from people who "develop new" scams and when everybody realizes it was just a new take on an old scam all along, people become a little jaded and sceptical about any new development that isn't from a well known company. These scammers really penalize two groups of people: 1. Those who forked over cash and 2. Independent creators and developers, inventors and startups.
*Viewers:* Please read this comment & give it a thumbs-up to keep it on top to aid in dialogue.
After considerable research, I've decided to use a heavy-duty #25 chain to raise input speed to the SIVAT. The SIVAT is a reducer, meaning its highest ratio is below 1:1, so raising its input speed (its sprocket) will compensate. Note that the overall 'gear ratio' on a bicycle must include the ratio of the front sprocket diameter to the rear sprocket diameter. By going from the standard bicycle chain pitch of 1/2" to 1/4" pitch, the rear sprocket diameter can be cut in half to increase the chain-drive ratio by a factor of 2 while keeping the front (crank) sprocket the same diameter. I've discussed this at length with a Tsubaki chain drive engineer (also an avid bicyclist), and he considered it very workable. The smaller chain actually has more working strength than typical derailleur chain, owing to greater width and cylindrical pins as opposed to barrel-shaped pins. The special sprocket sizes will likely be 95 teeth at the front, and 13 teeth at the back; giving the bike a high gear ratio that's equivalent to to a 48/11 combination which is the high standard for mountain bikes. Road bikes may use 105 teeth up front. High quality #25 chain is readily available, and I can include the sprockets & chain in the SIVAT kit so retrofitting the SIVAT should be fairly simple.
Hard-tail bikes and full-suspension bikes with a unified rear triangle will be able to use a lightweight shroud to encapsulate & seal the entire drive system to keep lubrication in while keeping mud, dirt & rain out because the chain drive requires no derailleur or chain take-up idler with the SIVAT.
I encourage viewer comments concerning this non-standard size chain/sprocket drive system. I've done this before on a very early prototype of a very different CVT, and did not notice any problem. Maybe other bicycling engineers or cyclists have some thoughts they'd like to share here.
+SIMKINETICS Great to see you are still commenting! Has there been any progress made on this since this video uploaded?
+SIMKINETICS I think this guy is a con artist.
2008 and what still in prototype no new videos.
Shit in 8 years a person could have a degree of their own and he can fuck off.
I don't see any new videos?
He talks about (The new design) where is that?
I saw a video right before this video some jack ass turned out he has no prototype you are donating to his church.
A lot of these piece of shit Religious people do that.
Free energy/pie in the sky new technology.
Often turns out to be a hoax you know a hoax because they leave out details or hide the area that would give away(The secret) they use things like this as a gauge for how dumb you are.
If you will believe they have free energy shit you will believe anything.
Like what's in the bible.
A perfect target for Religion.
Don't be a target tell this guy to produce a working product we can buy or admit it was just a con.
+Chris Tindall Lol con artist? What money or property did he con from you?
What is he asking from you, just because someone has an idea and nothing has spawned from it or you don't see it in day to day life everywhere doesn't mean anyone is scamming or conning anything from anyone.... Wtf are you so salty about?
+Chris Tindall what are you on about?
Could you please do a video showing the internal mechanism of this transmission? Very interesting.
So, its been 10 years. The modern world of cyclists would really appreciate such a marvel being implemented in every day cycling. Hows progress?
For real
I just got a bike and would really like this upgrade, also hoping they finish and market them soon.
Especially since his concept is so much more low-profile and ergonomic than the other one I saw so far researching 'automatic bicycle transmissions'.
I'm sure this is a scam tbh.
@@raymondcasso7966 no, its not
Here's an update on the status of the SIVAT. I have potential funding for an initial prototype or two intended for testing on bicycles. This requires implementing a fully engineered design that fits goals for size, mass, power, efficiency & durability appropriate for bicycles; this is an extremely complex process of multiple calculation iterations to determine a balance of gear, bearing and structure sizes throughout. My initial goal of 1.0 kW power @ 90 rpm input appears to be too ambitious, so it will require rating the SIVAT for less torque at 90 rpm (optimal pedaling speed) input and commensurately lower power, but still within typical pedal-torque performance required by mountain-bikers. 1.0 kW throughput will likely be at higher input speed than 90 rpm. The intention is to provide a single core design that can be used on bicycles in various locations (hub, bottom-bracket & auxiliary), as well as on other small vehicles & machines. It now appears that my mind-numbing number-crunching is only in its early phase! Thanks to interested viewers whose patience I appreciate as not being 'infinitely-variable'!
Use kickstarter to gain funding perhaps? This is really cool and would love to see it produced. Well done.
*****
Thanks! Yeah, a crowdfunding is most likely after the next video of a functional unit being used on a bike, fully engineered. I'm now in the process of thoroughly calculating its power throughput with updated design for real-world performance.
Only thing that's "mind-numbing" is it's stupidity and the suckers that think this is real. A classic example of 'bullshit beats brains' albeit very low intelligence brains.
Why not simply go for a CVT with belt?
Works for scooters.
Muranaman
Mountain bikers would never go for the added weight, bulk, inefficiency and erratic operation of a VDP That's not an optimal drive system for any vehicle. Even a scooter deserves better!
Nevermind, this sounds like it's a prototype and that's why I haven't seen it in the real world. I can't wait to see this in action in the future.
Thanks! The featured proof-of-principle SIVAT did prove the principle, but was woefully inadequate for power throughput of bicyclists. Engineering this concept indicates a needed, very challenging change in much of the design to achieve product-level performance without growing excessively in size or mass. Now, I've got the tiger by the tail!
@Barnacules Nerdgasm I always mistake you for that tattooed magnetics&electricity guy. Who apparently has come up with some pretty groundbreaking ideas regarding how light magnetism and dielectric phenomena function in out realm.
@Game Plays 1230 Yes, as a general rule, the transmission should be in its highest gear ratio at launch & initial acceleration, and then lowering in its gear ratio to accommodate acceleration & higher speeds. This is precisely what the SIVAT does.
My research & personal experience confirm that the most efficient & comfortable riding uses a transmission that keeps pedal-force and cadence fairly constant at all bike speeds; so that's what the SIVAT is conceived & designed to do automatically. A notable exception is the launch that has no prior force to urge it into its highest gear ratio, so I had to allow a 'lockout' of the automatic feature to keep the ratio high just for that launch from first pedaling.
I first tried out this spring-reaction control on a predecessor prototype CVT many years ago, and discovered that it works extremely well on steep mountain roads as well as in flat rides, both ascending & descending.
I'm convinced that this torque responsive control is the best way to control any CVT, and so is the automotive industry!
@@SIMKINETICS any more updates on this?
@@SIMKINETICS also, are you still open to investors?
Thanks yourself! As an avid cyclist for decades, I've always tried to imagine the perfect bike transmission. As a mechanical engineer for decades, I've realized that it's possible. Inputs like yours help shape & refine what will be the outcome.
These concepts can be made at any size to power anything a bike a motorcycle a bus a train a city power grid and so on. You got yourself a great little transmission there. = )
wow that is awesome. I like how it can do zero ratio, that means you can eliminate the need for a clutch as you just keep it at zero while an engine is running then u just increase ratio very slowly , thus the unit performing the job of clutch. Love it.
Yeah awesome man, love it how the output can be stopped completely just by touching a finger on it, that's going to be really useful for all bike riders when they connect it to the wheel. I wonder why no funding has been given.
James Allen ji hi l
Very nice work indeed, pretty genius.
Thank you. You're most gracious.
WP 👍
BTW, I believe that the SIVAT indeed has certain capability to become something like the "Holy Grail" of bicycle drivetrains, at least if the conception will be executed at the highest technical standards.
So I’m curious to see and test ride a SIVAT in the not too distant future.
Your response changed my mind. Again I apologise for my ignorance and facetiousness. I hope you carry on with your interesting and important work and recieve the recognition and support you deserve.
Overload? Oh god...
>Biker goes up 40 degree hill
*Overload kicks in*
>Biker starts going backwards
"Oh shit"
Aaron Lowe Actually, the simplest version of this has an intrinsic 'hill-holder' feature; the driven wheel won't go backwards! I have to add a release mechanism to allow backward rotation. Regardless, biking up a 40 degree hill ain't gonna happen... 30 degrees is a boundary beyond which the rider will wheelie over backwards, which is the limiting angle used to determine maximum wheel torque I use for design overload. You might fall over sideways when you stop, but you won't roll backwards on any ascent without actuating the release device.
The torque-limiting feature will ensure that users don't over-drive the unit with an accessory over-sized motor. This feature will not suddenly act, but will simply keep lowering the gear ratio gradually until it stops driving at all or until the overload is reduced. I've done a lot of mountain riding myself, so I know that any sudden disengagement would be maddening, and avoid that in my design.
Why haven't I seen a single bike with one of these? Seems like a brilliant idea, is it less efficient than chain/derailer design?
what are you doing here?
Please see my response to DylanT, below. The SIVAT will be slightly less efficient than derailleur design in well-aligned (mid-position) sprocket pairs. I use planetary gear systems which have better efficiency than most other gearing types, about 99% each. I expect overall efficiency to be greater than 95% with the highest gear ratios' (for going up steep hills) lower efficiency skewing the average. Sprocket drives are the most efficient, but planetary gear drives aren't far behind. The SIVAT promises to improve pedaling efficiency of the rider that should more than compensate for power loss in the mechanism. After doing many calculations & subsequent design changes to balance component forces & speeds, I'm gaining confidence that this will be a product you'll see on bikes. Thanks.
@@SIMKINETICS it's been 4 years, are they on bikes yet ?
I'm convinced that the SIVAT will push the evolution of transmissions in general! Having been an engineer for many years, I've seen & designed numerous drive systems for a variety of machines that would benefit from overload protection & ability to achieve a wide array of ratios with automatic or manual adjustment offered here.
Yes, you're right! The 'strength' of the spring does determine that. When the rider initially starts riding, the ratio will likely be in a high ratio, but will automatically lower within a portion of the pedal stroke; so he'll have higher wheel torque for initial acceleration. I'm choosing a spring that won't allow the ratio to go too low under any normal conditions, including steep ascents. The rider will be able to adjust the spring to his preferences.
I wish to all of you Merry Christmas, Happy Hanukkah & to all a happy holiday! May peace be the great fortune for you all without exception! Together, we can achieve universal peace & prosperity with nature & ourselves if we try.
Yeah, that too!
What's the maximum output ration? You mention "infinity" in relation to the lowest ratio being 1:Zero. But what is "currently" the most output? 1:3.6 etc
James Fry Thank you for trying to help. Are you suggesting the IVT, reduces or increases rear cog input? ~ It sees you are referring to changing the size of the Crank gear : Axle gear. I would like to better understand the IVT itself.... It seems to be an infinite gear reducer....does that seem correct to you?
***** James is correct. The next generation prototype will include step-up gearing to raise the top ratio without depending on a large front sprocket for bicycles. The SIVAT will still work in the same manner, allowing a higher top ratio without affecting its ability to achieve very low ratios down to zero. This will enable use of a small front sprocket (30T to 36T) with excellent ground clearance.
A ratio of one to one is lousy for a bike to gain speed. You need at least three wheel revolutions to one full crank to achieve a reasonable amount of speed on a bike. Currently a ratio of 5 to 1 is needed to hit top speed on a bike.
do you have more videos of this its been 8 years?
Thanx. You're not alone. You & many others are the reason we'll be making the SIVAT into a product. My own disappointment with derailleurs led me on this long pursuit to offer something much better.
You should start a kickstarter campaign. Almost 4 million views and I just stumbled upon this today. It's a bummer this product isn't available yet. KICKSTARTER CAMPAIGN PLEASE! :)
"if i stop the output, the output stops completely" witchery!
+JohannaMueller57 STEM!
SIMKINETICS
i dont speak russian.
JohannaMueller57 Science, Technology, Engineering, Mathematics: STEM.
+SIMKINETICS APOK!
I want to build a mini bike or go kart with one of those transmissions
Little kids (and big kids too) should have these on their tricycles. Cheers!
Thank you. I used to be a hot rod, and knew quite a lot about high performance cars at the nuts-&-bolts level including the effects in competitive driving; I raced autocross. Be assured that that helps a great deal in M.E. Automotive transmissions are a target market for the SIVAT. Once proven on smaller vehicles, I'm sure that it will enhance performance in cars with scaled-up versions. The numbers indicate that it will likely be smaller than conventional units.
I love building engine powered bicycles this would be far more efficient than a jack shaft
Beccy Mosser It's called a motorcycle :)
+Andre Gross their 2 completely different things
Okay, then a Moped.....
This would be perfect for motorized bicycles
Since the have no changing gears at all....
Indeed! They're on my checklist for design requirements for bikes with IC engines and electric motors, possibly up to 1kW (1.34 hp) of power capacity. Most of the core mechanism will work for pedal-power and motor-power with a single design for better economy-of-scale in production.
Make a version for the gas bikes. I'd love on on my 80cc
peter medz
We might not offer a SIVAT for any specific e-bikes or gas bikes any time soon, but a kit for you to adapt to motor/engine power will follow its initial pedal-power marketing & sales.
"This would be perfect for motorized bicycles"
Except electric motors generally don't need gears.
Huh! I just invented the same mechanism. It's so simple it's mindblowing it hasn't been in general use for decades. Good luck to you!
I just want to congratulate you on two counts - firstly for doing this in the first place - and secondly for the patience and politeness you show in this column!
I'm a lifetime ME and MTB-er (just to wind up the anti-acronym brigade!) following your progress with hope. An application jumped into my mind; hybrid cars use Rankin-cycle IC engines to get 15-20 pc fuel saving; a much wider range of vehicles could use this engine type, using your trans to stay within its smaller efficient rpm range.
This new YT format sucks.
can this be fit to old road bikes from the 80's 60's etc ? so no need to pedal is this correct ?
godsthunder26 I'm redesigning the SIVAT. One goal is to provide a core that can be adapted to any bicycle with a minimum of special optional parts. You'll still need to pedal it unless you choose to motorize your bike; adapters will likely be offered for its motorized use too. Without leg or motor power, you won't go anywhere except downhill! Maximum power throughput will be 1kW, which is ~4X typical pedaling power for athletic MTB riders.
He has the end of the chain we don't see hooked to the pedals, powered by an external source. Like an electric motor. If u notice, the chain seams to turn at a constant rate after it's rotation is started. The lever he is moving is the linked to the variable output. So as the lever input changes, so does the speed of the output shaft. No matter the input shaft's speed unless, the input isn't turning. Don't divide by Zero, lol.
His device is mounted on the wheel, or hub (back end) of the bike. The device can replace the transmission (ten speed, 15speed, etc) assembly with just one device on the rear hub. It has no power output within it. There is no motor inside, but a very neat device.
ptrainenator thx! so no more derailers and stuff like this ? impressive a more symetrical more agile bike ? perhaps ? lets see how it works and lets see the cost ?
ptrainenator Close! I actually turned the bike's crank by hand while keeping a constant pedaling rotation speed. The front sprocket is 55T, the back sprocket (the SIVAT 'input') is 11T; so the whole system has a 5X speed increase even before SIVAT affects it's own output. In the newer design, the gearing up is internalized w/ a 2.7X ratio so that the chainwheel can be as small as 32T for great MTB ground clearance & a very high top gear ratio. The bicyclist can choose his preferred front/back sprocket sizes without losing the ability to achieve all overall ratios down to zero!
Lots of wordz and a shiny can
I personally believe it to be a false claim (hoax). Especially the part at 5:17 where he says that the output will come to zero rpm in an 'overload' situation. Just thinking, how handy this would be (NOT), if this was on a car and you were going up a hill.
So how is a braking a slushbox down to standstill different?
mikokuijn Not sure if that was meant for me, but in any case I didn't understand it.
mikokuijn
Thanx for your response. The problem with making a speed responsive bike transmission is that pedaling hard causes an upshift when you want a downshift! If you pedal forcefully in one ratio, the bike speeds up with that scheme, sending it into higher ratios. I figured that torque-responsive ratio change is better, and proved it decidedly riding with an earlier automatic CVT. The SIVAT will deliver what you're asking for without electronics. It's actually simple.
This transmission should be made for use in go-karts and or mini bikes. I think many people would want one.
No video of it actually working on a bike? Probably slips when under the slightest payload. Show how effective it is. Put a wheel on your bike, ride it up on an extended incline, shoot and post the video. Talk is cheap. To see is to believe.
I think it might just about be able to transmit enough torque to pull the skin off a rice pudding.
Talk is cheap, but prototypes are not. The next video will feature a working prototype for testing on a bike with mountain riding. Posting this concept video has garnered enough interest to justify costs to take the concept to the next level. This concept has no prior art from which to design a perfect initial device; it's a totally new idea. What was learned from this proof-of-principle unit was used to fully sort-out what's needed for a real-world mountain bike transmission in a second design. By showing this concept first, potential customers are offered the opportunity to help determine its viability in the marketplace. Both public interest and engineering calculations indicate that the SIVAT should move to the next level; a pre-production prototype that's fully capable of processing the physical power of highly athletic mountain bicyclists ascending the steepest mountains they can ride. As a seasoned mechanical engineer with decades of experience, I'm reluctant to waste anyone's money on a losing proposition or a planless approach devoid of adequate research. It takes more than one step to succeed with a new idea.
Oh look, talk is cheap... that "Next video" never happened?
9 years video. Still nothing.
I'd suggest if there's not a prototype working on a bicycle then the project isn't serious enough. It has been 7 years since this video was posted.
There's no disclosure of how it works (or view inside) so it can be seen only as a concept.
Not that a cvt isn't a good idea for a bicycle but working prototypes are the real proof of the pudding. Even if it's an unconventional bicycle with the device outside the hub (perhaps a gear train going from crank to the device then another from device to rear hub).
The model being shown isn't carrying any load so it's not very convincing.
If there was a clear disclosure of the internals you'd be prone to get descent review and support and likely find someone to help.
Do you have a Web site or something serious for this project showing the details?
+Darcy Whyte You'll be in for a surprise. I've recently re-started this project with the goal of building a working bicycle-mounted prototype for a demo in 2016.
As for showing the insides, that would void the patent application(s); something I'd be foolish to do! This video admittedly is about a proof-of-concept, a starting point from which I anticipated finding design weaknesses that are not associated with the concept, but rather with its specific implementation of part sizing & potential re-design to correct its few initial design errors discovered in testing this unit. The basic theory is sound, and the re-designed prototype won't grow much in size or mass if at all. The demo will show an athletic bicyclist riding on hilly terrain, and some test results.
+SIMKINETICS I will be surprise. If you're going to get a patent, you're likely too late. This video is 7 years old. The grace period isn't that long.
+SIMKINETICS Good on you. 'Smart, interesting video. As an everyday cyclist without a car, I'd love to have an automatic transmission on my bike, and I really hope you succeed. Questions...
- Rough idea of likely price, if you can estimate it
- Ideas about electric drive with a lithium ion battery
- From a few years' experience of an Avanti Electra front-hub electric bicycle motor, a flywheel will produce very bad 'twist' effects at 90 degrees axis. I would discourage that, even for recovery of energy, and even on the back I guess. It also adds weight. And batteries are getting sufficiently capacious to obviate need for a flywheel.
Bruce Thomson in New Zealand.
+Bruce Thomson Thanks! My goal is to get the price within the range of that CVT you sometimes find on bikes, a few hundred dollars as a kit or added as a standard component on some brands. The first units will likely be higher-priced to amortize some of the start-up costs, but eventually automated fabrication & assembly efficiencies can make them quite affordable because the design isn't more exotic or complex than 7 or 8-speed hubs. My engineering career involved much automation design, so I'm designing it from experience.
The flexibility of wide-ranging variable gear-ratio choice enhanced by a microprocessor would help both battery life and motor dynamics on an e-bike. I've done fairly extensive research on that, and will do more before we get to that point. E-bikes may be a substantial market for the SIVAT. SIVAT power-density is high enough to make that quite practical up to about 1.0 kW throughput or more.
The flywheel energy conservation scheme I referenced was never intended for certain small vehicles for the very reason you cite. However, I'm aware of methods to eliminate gyroscopic effects that make the scheme appropriate for vehicles that can handle the extra *weight!*
+TheLegoman0077 Thanks! Once I get the working prototype (next-gen) build on a bike, I'll ask for some volunteer testers to help evaluate the SIVAT. My personal tests on a somewhat related automatic prototype suggest that it will please even hard-core mountain bicyclists. My latest iteration will likely offer an optional fully-sealed version that will avoid contamination from the drive-sprocket/chain-drive system to the hub, and better ground clearance than current derailleur drives.
Thanks. FYI, IVT is a term for the special case of CVT's that have no bottom limit in ratios. That's explained in the Wikipedia article on CVT's. In effect, it references the IVT as uniquely being capable of approaching infinite input-to-output ratio. The big dogs already know this.
By convention, transmission ratios are output speed divided by input speed. The newer SIVAT ratios will vary between ~3:1 and 0:1 internally; the high limit is raised by the external sprocket ratio, so the 5:1 sprockets in the demo would provide a 15:1 final high gear ratio! Using a much less radical sprocket combo (like 34T front to 16T rear) would still get a higher top ratio than road bikes have.
Wait, so you could literally have the pedal be connected to that lever. when not pushed, there's no motion, and as you depress it the speed increases? This is incredible! it's literally a powered takeoff. This completely eliminates shifting gears, the only thing you need to change is the variable ratio as you drive. This would be perfect on a gocart, you could just have the engine run at normal rpm's.
Has this become a product yet? If so, i'd love to just purchase one for experimentation.
+Tower Crisis Look up CVTs for ATVs and go karts. Same exact thing.
+Akash Hegde Not! Those drives rely on *dynamic* friction that's dependent on losses. The SIVAT uses *static* friction. The difference between dynamic friction & static friction is most important as a metric in efficiency; the static version being nearly without loss! I do not want to throw away power & energy! Do you?
where to buy?
The SIVAT will provide pedaling resistance similar to modern derailleur systems, but will allow you to globally tune that resistance force by simply turning a knob that changes the thresholds for ratio change. The range of ratios will extend into both higher & lower ratios than is practical w/ derailleurs. The goal is to keep pedal resistance & cadence within a narrow range despite the grade of the hill you're ascending or descending; that optimizes pedaling efficiency.
Just watched this. Belated congrats to yr son on his PhD. And you guys keep inventing!
Buck Rogers Thank you.
This is idiocy. You can never have a gear ratio of 1:0. Anytime you have input speed, there has to be some output speed. Looks to me like you've put a clutch inside a case. Cool invention bro
Why isnt this being commercialized??
Because he's afraid that the second he puts it on the shelf, someone will take it apart and share the plans of the internal workings... As easy as it was for him to cut it out on his CNC is as easy as it would be for someone else to do the same and shut it down. This is my opinion. Hope I'm wrong. Good luck.
makes little sense since there is patent option
That's an excellent comment. The answer, ironically, is in your YT name! I learned the hard way, in real estate transactions, that timing is very important for business start-ups and large money transactions. You must know about minimax principles. Commercializing a brand-new invention is not merely about demand, which is apparent; it's also about significant capitalization, sustained funding, supply-chain stability, distribution & ROI. Investment capital is tight now for a reason; the American economy has too much uncertainty, with global ramifications. When I see these economic risks in a sustainable downward trend, I'll get that ball rolling, likely with crowdfunding or similar.
Regarding a patent or any disclosures, I have a strategy for timing that too. For security purposes, I won't discuss that.
SIMKINETICS well, I wish you luck, hope to see this soon, and hope it makes bike riding more efficient and enjoyable. You know with fuel prices and pollution we should all get around on bikes when possible.
SIMKINETICS have you ever heard of crowdfunding websites out there like kickstarter or quirky?
When your gear ratio is too high, the rider will naturally use more pedaling force on any bike. The SIVAT ratio control mechanism is spring-loaded toward high ratios, while also being reactive towards lower ratios from pedaling torque. These opposing forces are in a state of equilibrium when the rider is pedaling within a narrow band of torque (force) regardless of the SIVAT's ratio; outside that narrow band, the ratio will change rapidly toward low, slowly toward high until new equilibrium.
I think one of these would be great to get me up Mountain Charlie road. I hope I hear about this as soon as it's commercially available in a bike. Thanks again for the directions. - David
not much info on this ie max torque or hp. just another black box to waste my viewing time!!!!!!!!!!!!!!
why Americans talk more than do
wael pauomi ...............BECAUSE WE'RE AMERICANS! DAMN BRO....... Duuuuuh.
Thanx! The seccond design is intended for hard use on MTB's & motor-powered bikes. It has a universal design which can be adapted for hub, bottom bracket or a separate location such as at a F.S. pivot for the rear suspension. A bottom bracket version would be ideal for weight distribution & would allow an un-idlered chain drive like a fixxie, but would require a special bottom bracket on a hardtail. Its very high top ratio will allow a very small chainring like a 32 or 34-tooth size.
CVT for bicycles is a pipe dream.
That is precisely what the SIVAT is designed to do. When the grade of the hill levels off, it resumes toward higher gear ratios. Reviewing the mathematics involved in the geometry of its automatic shifting, it turns out that the shifting mechanism can be simple for regulating pedaling cadence & torque within narrow limits; the goal of efficient pedaling on mountain trails.
One of my goals for the 2nd design is to raise its power throughput to enable use w/ motors up to 1 kW. This isn't easy considering weight & size constraints for a bike, so this is taking more time than I expected. I've also considered the same design to be used as a bottom-bracket mounted version and a hub-mounted version so that most components are the same for both versions; this should ultimately give more flexibility for the end-user to arrange a motor-drive for mopeds either way.
I would love a transmission like this on a sports car with a manual configuration. A lever in the center console allowing you to adjust the ratio manually would be a real experience to drive. Unfortunately no car manufacturer would ever build such a machine.
Challenge accepted
@@lavabuckett6278 are serious? This is my dream.
On the prototype shown, the input is 5:1 (55T front sprocket, 11T rear). The second generation will have an internal high output-to-input of about 3:1, so it doesn't need such a radical sprocket setup on its external input.
Amazing Barry! While on the road for long distances I ever shifting gears to get up and down hills. on tips of 250 miles or more my hands can get very tired of shifting and holding the handle bars on conventional bicycles. so what ever it takes to modify a bicycle to make the ride more comfortable to increase endurance is a plus. Thanks for using your mind. I hope to see the future of this technology become commonplace
Thanx for your interest! I'm in the process of working out the complex details of licensing the SIVAT technology to a maker of products that can use it. After an agreement, we'll start developing it as a product. That will take many months before it's available to you. The SIVAT does not rely on traction like toroidals; it relies on gears for positive engagement. The Brazilian marketplace is likely an early recipient, so keep looking for it! It's a good choice for you!
I've been an engineer for 1/3 century, & I learned early on that it's far better to do research about a subject before critiquing it. Research is very easy with the internet; if you teach yourself how to dig up & discern fairly complete, relevant, accurate information, you'll be armed to quickly develop a defensible opinion. If you want to become an effective engineer without losing credibility amongst your peers, research is the first step. Engineering is dependent on information & facts.
barry even though I didn't get all of the tech stuff I do understand the principles behind this device. Very ingenious in design and well thought out for applications that will make bicycling a new a very exciting thing again. I for one appreciate the stuff people like you do for the rest of the masses that have limited resource to be able to not only put so much into the actual product development but also the reasoning behind why it would be such a big leap in technology for something so simple as a bicycle to move us around.
Have you thought about any practical design or designing for/with wind or hydro turbine/generation? I think this could revolutionize that foeld as well.
+Steve Frappier It looks like your comment was for me instead of brian noel, so I'll answer your question. Between my own ideas of how this transmission can be used *and* ideas suggested by viewers, we've come up with over two dozen practical uses, including wind & water turbine power. After doing extensive research into wind turbines, it appears that the SIVAT would help protect the expensive drive-systems from damage due to strong gusts, and would eliminate the need for some of the expensive control electronics that modulate power output AC frequencies. Generator input speed can be controlled by the SIVAT for constant speed & frequency operation, while air flow (or water flow for hydroelectric power) varies over a wide range at the impeller. Thanks for your question!
Thank you for answering, and so promptly.
It's refreshing to finally see a thinker and doer after such a long time without. Your idea and its applications will, indeed, go far. Thank you for sharing.
Best of luck to you, Sir!
Steve Frappier
Steve Frappier You're welcome! And thanks!
Thanx for digging a bit deeper! I want the SIVAT to be an excellent MTB transmission in every way. About 20 years ago, I co-founded a riding club, so have had the opportunity to observe what MTB riders need & want. These YT comments have been adding to that. BTW, we will be working on getting the mass down to a minimum without sacrificing durability & easy maintenance.
I'm a big guy who's destroyed the 3-speed hub repeatedly by bicycling in mountains with it combined w/ derailleur [hybrid] gearing. This experience taught me about what's needed to design a tough alternative that's lighter & stronger. I'll test the SIVAT for durability. It will compete w/ the remarkable Rohloff, & will likely beat it & the NuVinci in efficiency, longevity & weight.
The patent is in-process, and it is unique as an invention.
I've looked into wind turbine applications intensely, & I agree with you. It's also obvious that the auto industry has a 'not-invented-here' attitude. We've deemed the bicycle market as an excellent entry point though because bicyclists are most open to technological advances, especially where that tech imbues their experience with a more intuitive feeling & better care-free performance. As an inventor, you'll surely appreciate that customers are king.
Thanx. The ratio-control mechanism won't be cumbersome because it works automatically. It shifts ratio according to your pedaling force, something very natural & non-distracting. I got the idea originally from those old Sturmey-Archer 3-speeds that you could pre-shift up & expect to actually shift by very briefly relieving pedal force; great for drag-racing on a bike! The SIVAT refines that experience.
Overload protection will be user adjustable within the power rating of the SIVAT, and is only included to prevent catastrophic failure in the event of abuse. It's occurance will be very rare,very subtle & easy to recover from.
The current design increases its intrinsic highest gear ratio to ~3X, so it's no longer a reducer only. This change enables use of a modest 36T/18T sprocket combo to achieve gear ratios higher than most bikes.
A great invention sir. I can see the future of this product utilising hydraulics and a shaft drive.
It can be controlled with a handlebar-mounted lever too. The main intended control method is the rider's pedal force which was proven to be very natural by a similar, earlier CVT. We'll test some variations to determine what control system riders prefer.
Thank you. Like you, I've done a lot of bike riding, preferring riding in mountains, and have experimented with modified gearing (for several decades) to accomodate getting my large body up & down steep hills. Shifting gears is often problematic & annoying even with today's refined derailleurs & hub gears. Riding with a predecessor auto-CVT, I discovered the surprisingly intuitive nature & efficiency of smooth auto-shifting; my goal here is to refine that for all types of riding & riders.
That was the DAF. It used a VDP (Variable Diameter Pulley), similar to the friction drive belt system used on some machine tools.
I built & used a CVT version of this on a bike. It worked very nicely on hilly rides, but didn't have the ratio range I wanted. This IVT version has more than enough range now. I've done a helluva lot of bicycling in mountains, and designed the SIVAT specifically to address pedaling efficiency, supported by research into bicycling ergonomics done by sports physicians, & by studies of elite bike racing pros. Consistent input (not output) cadence & force are the result.
Good question. I deliberately designed this to respond to overload far in excess of most bicyclists' power output. It's there to prevent abuse with over-sized motors exceeding 1.0 hp. An uphill start will be a positive drive at a fairly low ratio. The user can adjust this per his preferences within safe limits.
Derailleur systems vary between 92%-96% efficiency depending on sprocket/chain alignment, but only as well-lubed & clean. The SIVAT is estimated to be 87%-93% efficient, also dependent on ratio with very low ratios least efficient; that will be tested in development. Ratio range: 3X to 0.2X at hub; multiply these by your sprocket ratio for final over-all ratios. In theory, the lowest is zero, but only if it's over-torque at input (nearly impossible for bicyclists).
Notice that the drive chain converges toward the rear sprocket. The input is 55T/11T, or 5:1. Multiply the SIVAT ratio by 5! Regardless, the new design is ~3.6:1, making a very high top ratio with a smaller front sprocket.
Notice that the chain converges to the back sprocket. The front sprocket is 5X larger than the rear sprocket, so the actual gear ratio is 5X higher than what you see in the SIVAT alone. Regardless, the new design will include much higher ratios on its own.
You're forgiven! It would take hours to read all the comments. Torque-sensitive ratio control makes the most sense by far; I extensively tested my own auto-CVT predecessor in mountain riding, so I can assure you of that. Peak input torque automatically limited to ~100 Nm (an industry standard), & will be user adjustable on the unit. Peak output torque:~200 Nm. These values would accomodate world-class sprinters with their 'explosive' pedaling. A ratio lock lever will be included.
"Regardless, the newer design will have a ~3:1 internal hub high ratio, so even fairly small front sprockets will deliver high gears." Good to see you're still plugging away at this device Barry, can't wait to see the results. You should get onto Kickstarter so the peoples of the world can throw some funding at you =)
As one who's done a lot of mountain riding & shifting gears on both Road Bikes & MTB's for several decades, I sought a better way. Once you ride with this, you'll understand how well it responds to changing grades while leaving your MTB experience to focus on steering, braking & pedaling. I intend to make the experience of shifting w/ leg force a trouble-free, efficient, fluid & intuitive ride with more range than current MTB's.
Yes. I've looked into this for wind turbines, and it offers many advantages.
Yes. 20-to-1 might be close to the practical limit of high gearing. The method to achieve that is to use step-up gearing at the input and/or output. The new design SIVAT has an internal high ratio of ~3-to-1, so you'd need to use 7X gearing. Note that the video version has 5-to-1 at input by using a 55T/11T sprocket combo, so the whole system has a high ratio of ~4-to-1. Very high ratio transmissions usually are less efficient in general.
Thanx. Yes, you'll be able to drive the hub directly if you use a large rear sprocket. 250 watts won't be a problem, but you might need to change the spring that controls the automatic shifting.
Yes, Mechanical Engineering student and master fabricator/tuner/engine builder for a racing group called Rebel Racing. I do tons of work with 3rd 4th and 5th generation GM vehicles, typically with big camshafts, and aftermarket torque converters to make up for their lack of low end torque. This would be an amazing unit if it could handle the abuse of 500-1000+ horsepower in cars, with an electronic controller to dictate stall speed. Good luck!
You're welcome. Getting one design into several uses will help bring the cost of production down. I've deliberately sized the 2nd design for power & physical size & shape to make it most universal for several likely applications like small motorized vehicles, conveyor drives, industrial machines & robots. Since I've designed some of such devices during my long career, I'm fairly familiar w/ those apps, as well as bicycles like MTB's.
Thanx! The new design will offer a 2.7X high gear ratio! That's big-time overdrive! Even disregarding the 55T/11T chain-drive ratio here for top gear on its chain-drive, The SIVAT will offer many options for input or output gearing at nearly all intermediate ratios!
Thanks. I now have a source for funding. But you're correct about Tesla; they once had a 2-speed transmission to improve efficiency, but abandoned it because their torquey motor broke gears on the shift from shock-loading. The SIVAT does not 'shift' with any disengagement/engagement cycle, so it should work well for their drive system. I've had them in my sights for later development.
The response has a fluid-like feel to your legs, very natural & intuitive. The ratio will lower to the extent of your pedal force; more force will cause the ratio to go lower, but only slightly more quickly, never abruptly. As the ratio changes downward, it will tend to equalize to cause your pedal cadence & force to remain nearly constant most of the time, regardless of grade. Upshifting will be quicker. You'll also be able to tune it for your personal preference & power level.
I have always dreamed of this infinite variable transmission for years
The SIVAT's ratcheting mechanism uses the same system that's used in most automatic transmissions in cars, so it's reliability has been very well proven, and is rarely the source of failure in those transmissions. The SIVAT's gear ratio has negligible effect on the speed or forces therein. It uses rolling sump lubrication common to all hub transmissions on bikes, so that's proven effective too. We'll conduct life-tests to find & solve any weaknesses before commercializing this as a product.
Yeah, this was brought up before. The intermittent motion you see goes away when the output provides some resistance. Without resistance, the very slight drag in the ratcheting mechanism dominates with a subtle erratic motion that quickly disappears under load. At very low ratios, this no-load irregularity is amplified, so you notice it only near the zero-speed condition.
For mopeds & pedelecs, the motor will be 'geared-down' to allow for the fact that motors generally run faster than pedaling. the newer SIVAT has lots of range & a higher high gear ratio to accommodate motors and/or pedaling on hilly rides.
Excellent, I can only think of making a two-speed transmission on a manual bicycle, but this one is quite good.
Excellent question! You must be an M.E. or student, as such! The SIVAT does not use hydrostatics, but measurements of heat propagation of a related mechanism indicate that losses are low, likely ~ 6%-12%. This will be tested on the 2nd generation prototype in at least 2 ways: via thermal mass transformation over time, and by dynamometer tests at various ratios. I doubt that a lubricant cooler will be needed; rolling sump cooling should do the job for bikes & motorcycles. Thank you.
Yes. I tested a bike with a predecessor CVT with a similar automatic feature; and that's exactly what it did. This effect will be attenuated with an adjustable damper that slows the response in the half cycle of pedaling action. One unexpected benefit from some of this action (in the earlier CVT) was reduced stress on knees. The rider will have the choice about adjusting this for his/her preferences, but even light damping is not objectionable as I discovered in my undamped predecessor.
If you ever do please update that in your video comments! This would make accelerating so much smoother, I'd love to have one on my bike!
The BitRaptor is a variant on the Epicyclics CVT that's been around since the 80's. It's 2:1 bandwidth (ratio of high gear-to-low gear) has limited uses, unlike the SIVAT that has infinite bandwidth.
Yes. The SIVAT has an unlimited number of ratios available. You might consider it as a thousand-speed transmission. Also, its highest gear is higher than most, & its lowest gear is much lower than any, with all choices in between.
Thanx! It's good to know that others, like you, appreciate the advantages of constant force, constant cadence pedaling on variable grades. Scientific studies of bicycling dynamics show that maximum power & efficiency result from such regulation as a consequence of our physiology.
Current development is for a non-bike application, so the bike version won't be available for at least a year. The bike hub SIVAT will likely include 10mm & 20mm axle options. I'm also considering a bottom-bracket version for special F.S. frames to accomodate pedal and/or motorized MTB riding w/ very light rear wheels.
It's a completely different mechanism, and it does not 'slip'; it's always fully engaged without dynamic friction. A newer design has a higher top limit (2.7X) to its ratio range using a spring (instead of a rubber band) to adjust toward its upper limit unless throughput torque momentarily brings its ratio down proportionately. When torque decreases, the spring automatically raises the ratio.
Exactly! It means that you can be in the right gear so to speak, at all time.
Also, as it is nearly fully enclosed, it can potentially be a lot more maintenance free, and you don't need to worry about chains falling off from time to time because it doesn't need to jump from gear to gear.
We're working that out now. A purpose-built SIVAT will be featured on specialty vehicles first, likely this year. After that, we'll productionize the design for mass-production in order to make it affordable for more popular applications like bicycles & mopeds.
I read what you write as your observation that the output looks irregular at super-low ratios; that irregularity disappears under typical operating loads. The second design won't drop to zero output under any real MTB bicycling forces. BTW, when it does go to zero, it appears to slip, but it does not slip; it's still fully engaged, and cannot roll backwards at the output. It helps to know that the SIVAT works in ways unlike transmissions with a clutch.
This is awesome! One of the things in my ever-growing "to-do list" was to make something for a bicycle that would provide a constant "force demand" for the rider (ie the transmission adjusting to the slope of the road)
This uses gears instead of rollers to transmit power, so its power capacity is significantly greater for its size. Although current CVT's in cars are limited in power thoughput, they've proven to enhance systemic efficiency which can apply to cars with greater power using this approach.