According to Peak Torque, rolling resistance is the same for the same rubber compound at the correct inflation for the tire width. The gain is being able to have the same rolling resistance at lower pressure in a wider tire, which increases comfort and reduces vibrational losses. Also, pro tip I just recently realized after years of searching Contis for that little arrow next to the word "rotation." The HUGE pattern that covers both sides of the tire points in the same direction. The small end points in the direction of rotation. I felt like an idiot when I finally realized this. Hope this makes someones life better.
it is actually fine to run them any direction. originally the Continentals had that arrow just to prevent people contacting support to ask. It is possible that today its oriented for the best aerodynamics of that sidewall pattern but I bet it still doesn't matter.
@@irvingabbott6 because these kinds of outdoor tests are almost meaningless. Unless you take the exact same line, put exactly the same power into the crank for every second of the run, hit the exact same pebbles, deal with the exact same wind gusts, etc., you're going to end up losing or gaining a few seconds here and there no matter what.
This video was another banger. What I would like to know next is if it makes a difference to have a larger tire on the rear wheel than on the front wheel.
@@irvingabbott6 In that other video he was using 35mm wide (front) Roval wheels. That would seem to favor the 32mm tire. It might be interesting if this test had been performed with the Rovals. Then we could see if the fastest tire moves towards the 32.
My next question after this video is what difference mixing tire sizes front/rear will make. For these same wheels, if we take the fastest tire size you tested (28mm), and put it only in front for the best aero/rolling resistance, but throw a 30-32mm in the back to prioritize rolling resistance gains (since supposedly aero is less important for the rear wheel), will it go faster than 28mm front and rear?
You want the front wheels to be wider to break more air and this has already been accomplished by changing the arc of the tires surface usig varying rim widths. The outer rim width on some newer wheelsets have been wider on the front wheels than on the rear because of this actually (see CRW and Elitewheels Drive) by an insane 5mm (34-29mm) on the CRW cs wheels.
As I've said over 1 year ago: 28c front, 32c in the back and you get it all: comfort + aero EDIT: it also benefits: 1. Rolling resistance - most of the weight is in the back 2. Aero - the frame-tire gap gets smaller
Aero matters much of the time, rolling resistance matters all of the time. It's not a surprise that you could squeeze out a little performance by rolling smoother while deviating from the ideal aero by a bit. What I wonder now is if you tried 5 tire pressures on each of the fastest widths if you could close the gap.
We all know what happens when you change tire pressure. This entire comment is like, "ok?" Lol, the video is about the fastest tire and rim combo, rolling resistance and aero obviously matters here Also slicks tires have always been a thing
Silka, SRAM, etc. have already done the work of computing the optimum pressure for a given tire and rim width, rim type, riding conditions (wet, dry, rough, smooth), etc. The seem to recommend the same pressures for the same conditions, so it seems likely they're all pretty accurate. They could each be wrong by the same amount, but it seems a better use of Jeff's time to tackle questions that the calculators don't answer.
@@darrellstyner0001 I'll be the pessimist. You mean how every road tire manufacture, every pro bike team, and pretty much everyone in the industry believed 180 psi and skinny little tires were faster for many decades? I'd rather see a test to add to the body of evidence that we are heading in the correct direction.
Thanks as always! Would love to see that 28 + C50 vs say a 32 on a similarly aero optimized wheelset. Maybe get some aero-ish 29er wheels on haha. I'm doing a build with 32mm wide wheels, can't wait.
I use 28(29mm actual width) front and 30 (31mm actual width) rear tyre combo on ~29mm external width rim and it is soooo much better then 28/28. No testing on my side, but average speed on routine courses is quite similar, yet control is better and fatigue is substantialy lower.
Same question for me. If you tested again with 28mm at front and 30 then 32 at rear, my guess is that you could improve on the straight 28 results. Could well be wrong
3:40 the real goal is to make sure the whole bead of the tire is as deep in the channel in the center of the rim bed as possible. The beads tend to work their way out of the channel and onto the raised flat part of the rim bed and that's the slack needed to get the last part of the bead over the rim.
Great video as always, thanks. +2mm rear tire is also an option - 28mm front/30mm rear or 30mm front/32mm rear depending on rim width. With this set up, you would typically use the same pressure for both tires. Aero concerns are mostly for the front wheel. More rider weight is on the rear wheel. The fatter rear tire should absorb more shock, have better rolling resistance and handle better. The UAE team has used this set up.
Hey nice vid and all but maybe do something with the sound balance ? Music is waaaaaay too lound and speaking segments I could barely hear. Had to adjust the volume each time which is pretty annoying
You brought the emphasis of conditioning determines for most part the out come. To many vids place emphasis on equipment over looking how fit you are. Kudos to this video!
Check hollowgram knot 64 with 23tire. In my opinion one of the fastest wheel for flat roads)) Huge 32mm outer rim width - Helps air flow off a large tyre (26+mm) re-attach more smoothly to the rim, reducing drag. Only possible with disc-only design. Optimized for 23c (26mm) tire but, unlike other wheels, the KNØT 64 design exhibits minimal change with even larger tires, giving riders the option to go bigger without significant aero penalty.
Your testing vids are getting better and better, even the process part is now enjoying! You have come this far, why not test different FRONT and REAR tire width next??? We all know the front end is the most crucial part of aero, rear end, not so much. Now that you have established 28mm as the baseline, just try 25 front and 28 rear, 28 front and 32 rear, 25 and 32 rear. See if this could give us some more insights. Anecdotally I current run 25 mm GP5K TL (the previous version) at front and 28 mm Schwalbe Pro One at rear. My rim is not so wide, I believe they were optimized for 25mm at the time, with 28mm on, I get that little bulge (you can feel it just by run your fingers through), but with 25mm it's smooth and flat, even ever slightly narrower than the rim. Even though that 25 GP5k is somewhere about 8000 km old and at its end of life, my feeling is 25 mm still "seems" faster, and "feels" more stable in the wind. Tires are so expensive now so it's not possible for me to do the test ourselves. We are all looking up to you now, Bro!
Glad you mentioned the rule of 105 in this one, that was my question from that last vid, 'Is rolling resistance more important than the rule of 105?' have a set of 30c GP5000s on the way for my Roval Rapides hopefully they work out to being a good balance between the rolling resistance and aerodynamics.
i have seen people do it with these same tires and it really didn't make any difference which make sense because these specific tires have very little thread and really all the thread it has is mostly just for looks. with tires that have actually functional thread the tire direction makes alot of difference and it is very noticeable.
It might not make a difference in rolling resistance but I'm very certain it will make a difference in grip especially while cornering at high speeds downhill
Would like to know what size frame everyone rides vs their height, similar to your video looking at what tires and stems everyone rides. Maybe could discuss briefly how each person came to their frame size through their bike fit or what worked/didn't work for them.
The one thing that you have not tested is a more narrow aero tire up front and a better rolling wider tire in back. It is simple, aero is more important in the front and rolling resistance is more important in the rear. You should test this.
OK, now show us a mullet set up. 28/30, 30/32, 28/32 so you get some aero on the front, but you get better rolling resistance with the 30+ on the back. I’m rolling 28/30 and love it.
I think you should change to something faster. GP5K vs 4 Seasons, that's the mass gain here. That will offset any of these marginal stuffs. If possible, deeper wheel then. Obviously that's not cost effective but in terms of gain, that will still offset anything about this ratio thing.
@@xuchenglin6256 Yeah agreed 5000s would be fast for track and crit but the roads around here... i need that puncture resistance and assurances for Time trials.
Tx for the helpful video. It would be interesting if you can test it with 30/32mm wide rims and suitable tires, considering many companies are heading there. Then compare the results with the 28mm wide rims
Hey Jeff, I love your videos! I would really like to see one where you test protective equipment. Crashes unfortunately happens in this sport, and I'd like to see whether the additional protection is worth the potential speed loss of wearing that equipment. More than helmets, I've seen collarbone, knee, and elbow protectors, and even body armors!
Jeff, your videos are always great fun. The graph makes it look like the 28mm tire is dramatically faster but in the end it shows a 15 second difference out of a total ride time of 812 seconds? What is the margin of error for this kind of testing? My guess would be more than 15 seconds.
Regarding direction it doesn't make a difference for road bike tires, if you mount them backwards. Schwalbe said in an FAQ that it does not matter and that the arrows are purely decorative
Thats not always true. Thats especially not true for conti gp tires. The tread on gp tires have aerodynamic and water shedding function that certainly do not work in reverse.
If I ran what Silca recommended for tubes I'd have pinch flats left and right. It makes them slower because it's way too low. I ride 95psi with 28mm. Ride feels absolutely fine, and it's fast.
I'm running Bontrager Aeolus Pro 37 (int width 21mm,ext 28mm) with Vittoria Rubino Pro 28 mm tyres at 70 psi for my 80 kg frame. Huge improvement from the 700 x 23 c at 100psi I've been running for most of my riding life! 😂
I watched this video the day it came out, but 2w later I found myself thinking about it again as I was putting on new tires. If you have the ability to do this, Jeff, I think it would be really cool to repeat this while motor pacing at ~30mph to better replicate pack racing. Probably would require multiple runs to insure accurate results of each tire but you could also cut out the 25c.
I had an interesting thought on a tire's lateral deflection and how that might affect rolling resistance. I'm assuming this would only be an issue when sprinting out of the saddle using increased lateral forces on the bars. Under this scenario, would higher profile tires have higher lateral deflection and would the deflection negatively influence rolling resistance. Another thought on the higher profile of tires from 25 to 28 to 30s and beyond: If you are using the same power but the tire has a higher profile/ longer runout, won't you be covering more distance vs a lower profile tire.
I have a couch engineers aero theory of which i'm very curious about in real world results. What ive learned about aerodynamics is that you want to attach the airflow in the front and detach airflow at the rear so i run a 28mm up front and a 30mm in the rear for a conscious light bulb effect. PS. 28mm wide rim.
I believe the air flow is ALREADY turbulent by the time it gets to the rear wheel, so having a more comfortable, lower rolling resistance tire (consistent with the frame, of course) makes sense.
I'm also a couch engineer, but I think the idea is to keep the airflow attached as long as possible, whether in front or in back. This is why aero bikes have deeper sections. Attached air is always good. The light bulb effect is never desirable.
Match the wear indicators with the valve hole so you can find them later! On the Contis they line up with the logo; I don't know if that's true for other tires.
So funny how for decades we ran on 23mm, 21mm, and even 19mm tires without complaint, and now a 25mm tire feels unsafe. Hmmm...' But yeah, I really like my 28mm tubeless tires & wheels.
First dud I could see would know the correct way to mount a tire. I would only suggest to use both hands at the same time on each half of the wheel to center the tire toward a valve. Just nitpicking. 👍
What I want to see is the following: - Aero Bike with Aero wheels and your choice of tire - Ti ( round tubes ) or Aluminum or Steel with the same aero wheels and tire. That is the comparison you never see, not even GCN is willing to do that comparison. Can you pls Jeff do this comparison for us? Thanks
i was surprised you suddenly sent a picture of a Tirich Infinite, which is a bike sold most of the time in selected countries in Asia, but most of the time in the Philippines. costing around 212 dollars when converted, which is considered a low-mid budget for an aero disc bike.
The Flo wind tunnel study showed that the 105 rule applies at bigger angles of attack. At low angle of attack the advantage of 105 to 100% is negligible. So you might see greater benefits at big windspeeds from the side. I also noticed the silca calculator recommended way higher pressures for 25mm setups than the sram calculator, almost a whole bar more. At 28mm the recommendations are very similar. IMHO silcas recommendation for 25mm is way too high. As a result, your test run might show increased rolling resistance for the 25mm setup.
28mm front and 32mm rear should be the fastest probably. Most of the rolling resistance gains come from the rear wheel. The dura-ace C50 are surprisingly narrow.
3:50 I've changed my tires countless times and am bothered by how easy you made that look. I still have to revert to levers and caveman style grunting 😂 Huge fan of your channel by the way
would 30's on a 105% rim width ratio be faster than 28s on a 105% rim width ratio? I have been looking for wheel set/tyre combination videos/testing for months trying to figure this out.
Sorry but I would expect that ratio would be |tyre-width| / |rim-width| since it looks more like a tear drop which is the best aero shape... in that regard 28mm are closer to the tear drop shape.
That is one thing I don't understand with the tires coming off hookless rims in the world tour. I read that at least one of them was running 25s which is narrower than recomended. Why wouldn't they just run 28s since the rim is so wide. There would be no advantage to 25s at all. And note, I am not debating hookless rims. I am nervous about them myself for road. I am asking about their tire width choice.
I know it was Paris Roubaix but the average speed this year was crazy high so aero is mega important and VDP ran 32mm tyres on the Dura Ace 28mm rims. Wonder what he ran at Amstel Gold?
Super informative, thanks! I guess rims are going to be wider as the years go by, so we'll be able to match wider tyres without the aero penalty of neglecting that 105 rule. The pursuit of marginal gains that empties our pockets and keeps the industry up and running 🤪
How about testing a suspension (or Paris Roubaix specific) stem and saddle post compared to regular road stem and saddle post? Can there be any significant aero penalty?
Will try out 28c in the front with a 32c in the back this season. Is it the perfect mix of aero, comfort and rolling resistance? I don't know, I dont care, but I'll have fun riding my bike. 😁
Any way you can test out of your comfort zone? I’m curious about climbing Mt Madonna or a longer climb like Henry Coe. What size tire would be optimal on a climb?
What about different sizes in the front and the rear? It might work pretty nicely to combine 28 front and 30 or even 32 rear. I mean something like fast and comfy… what do you think about it? Is the rear as aerodynamically important as the front (I don't think so)?
Have you considered that basically all measurements could be within the same range, i.e., the impact is much smaller than the uncertainty, and the 28s are just an outlier? There are so many uncontrolled influences that this kind of testing is simply inconclusive.
ya it's possible, but the 25mm test duplicated gave me some reassurance, and so did the consistency between these tests and the tests done with the wider rovals (discussed towards the end of the video)
@@NorCalCycling - great video. My first thought was similar. Nearly all the runs had the same time (within 2 seconds) except 28’s. Was it the tire or the variables … Either way, great job on your videos and congrats on your channel. Actually have a set of Winspace Hyper wheels being delivered today. External width of 28. Sitting here trying to make a decision on tires.
@@NorCalCycling Perhaps to remove such reasonable 'testing' questions in future tests, measure the thickness of the tread on each tire, as this also seriously influences rolling resistance. There are potentially batch and size difference that could create such an outlier. 🤔 It's great you stuck to new versions of different sizes from the same model tire. (Good for me too as I bought 2x 23/25/28/30mm GP5000s to confirm which to use for the rule of 105 for my rim-brake Cervelo.) ETRTO (& many bike warranties) state that 4mm clearance is required all around the tire in both fork & frame. Does this mean that to combine the rolling resistance with the best aero, always buy the widest rim that will leave 4mm clearance and then select the widest fitted tire that matches the rule of 105 or goes closest, especially at the front? I saw you on Chris Miller Cycling and follow you here now, too. 👍
Hey Jeff, I LOVE these videos, however in this case I fail to draw the same conclusions from the data you have. In order to say 'buy the biggest rim width', you also need to compare a narrow rim with narrow tire setup. At the end of the day you still have two very large trailing edges on the front and rear wheel which consist of the tire (not a particularly aerodynamic trailing edge compared to the rest of the bike), and these are bigger (=more drag) if you have a bigger rim+tire combination.
narrow rim/tire is aero according to rule of 105. wide rim/tire is aero according to rule of 105. but wide also has better rolling resistance, puncture protection, cornering ability, and comfort at the cost of some marginal frontal area and weight, which is not really important unless you're not cornering and racing on fresh pavement or a velodrome.
@@NorCalCycling Agreed, but I'm not convinced that the frontal area difference is marginal when it comes to aero penalty. Though now I recall you may actually have some data from that from a previous video, so I'll go take a look and revisit!
@@carsonau116 The wide tire has a larger contact patch and can be run at a lower pressure. A sharp object trying to push through such a tire has to push much harder, which makes the tire harder to puncture.
For my TT bike setup I've got Bontrager Aeolus XXX 6 Front wheel which i think has a 21/22mm inner width currently Ive got a 25c GP 5000s on there. Not sure what the outer width is. On the back I have a disc wheel(race setup) with a 28c GP5000s. Not sure about this width at all. My Qs is, do I change the front to 28c or because of the potentially skinny wheel width I keep the 25c on there. Im racing a IM 70.3 this weekend a d want to be as fast as I can.
What would be your opinion on having say a 28 on the front and a 30 on the rear (with those DA wheels)? Will there be a front/rear difference in the aerodynamic effect vs the bigger volume etc?
Random inquiry, but are you changing the tubes? I use the Specialized Road Turbo Presta Valve Tube With Talc tubes that say they are for 20-26, I've always run 26s, but now plan to shift up per your findings here. What size / style tubes are you running? Thanks!
for this testing i used tubes for convenience, but since about 2022 i switched to tubeless. you can get away with using 20-26 tubes in 26+ tires it'll just stretch and be more prone to flats.
Yet again @norcalcycling you're begging the question. You can put different width tyres on different wheels. The rear tyre/wheel interface has very little impact on overall drag because it does not have a meaningful leading edge. The rear wheel contributes the majority of your rolling resistance. Put a wider tyre on the back. The front wheel contributes the majority of your CdA. Put a narrower / 105 compliant tyre on the front. On something like the DA C50s, this might be a 25F/30R, on you reserves a 28F/32R.
Thanks for the great content! Curious how you square these results with the results from your "How wide is too wide" video? The 32s in that test were much faster than the 28s. Obviously key test differences would be test wheelsets (35mm wide Roval Rapide CLX IIs + 28.5mm wide Lun Hypers vs 28mm wide DA C50s), power output, and tire make/model (Vittoria vs Conti). But still, if you were doing some test runs on the Hypers in that previous video, there would've been some tire combos way less aero than the 1.05 rule that were nevertheless significantly faster (i.e., the 32mm tire mounted to the 28.5mm wide Hypers).
I wonder if the bigger tire often actually having a bigger RAM(radius as measured) offsets the rule of 105 or something. Essentially adds a few mm of deep dish to your wheel in the form of tire. I know thats why 3T aero gravel wheels are only 45mm, they say the gravel tires add plenty of depth.
Hi , what do you think about quality of dac50 vs roval rapide clx, I had c24 DA and make some best time on my well known rout and change it for clx 40 rapide with ceramic bearings and was slower about 1 km h I dont understant it Thanks
Not necessarily - it depends on the outer width of your wheels. If you have wider wheels like the 35mm wide rovals in the previous video, 32mm tires would be faster.
All tire width rides fast Just remember your body weight will decrease speed Make the ride slow Make sure your body weight is low enough if you want to fly at high speeds
According to Peak Torque, rolling resistance is the same for the same rubber compound at the correct inflation for the tire width. The gain is being able to have the same rolling resistance at lower pressure in a wider tire, which increases comfort and reduces vibrational losses.
Also, pro tip I just recently realized after years of searching Contis for that little arrow next to the word "rotation." The HUGE pattern that covers both sides of the tire points in the same direction. The small end points in the direction of rotation. I felt like an idiot when I finally realized this. Hope this makes someones life better.
Interesting fact: They have that pattern because it supposedly improves aerodynamic performance of the tire.
it is actually fine to run them any direction. originally the Continentals had that arrow just to prevent people contacting support to ask. It is possible that today its oriented for the best aerodynamics of that sidewall pattern but I bet it still doesn't matter.
Yes! This video answers all the questions I had after the previous tire width video. And those tips for getting the gp5000s on the tire are gold!
I would be wrong but wasn't the other video saying that the 32MM was the best tires to use? @norcalcycling Can you explain the sudden change in tires?
@@irvingabbott6 because these kinds of outdoor tests are almost meaningless. Unless you take the exact same line, put exactly the same power into the crank for every second of the run, hit the exact same pebbles, deal with the exact same wind gusts, etc., you're going to end up losing or gaining a few seconds here and there no matter what.
just watch the videos, 32mm was correct on the rims we used in the other video, 28 was the best on these rims.
This video was another banger.
What I would like to know next is if it makes a difference to have a larger tire on the rear wheel than on the front wheel.
@@irvingabbott6 In that other video he was using 35mm wide (front) Roval wheels. That would seem to favor the 32mm tire.
It might be interesting if this test had been performed with the Rovals. Then we could see if the fastest tire moves towards the 32.
My next question after this video is what difference mixing tire sizes front/rear will make. For these same wheels, if we take the fastest tire size you tested (28mm), and put it only in front for the best aero/rolling resistance, but throw a 30-32mm in the back to prioritize rolling resistance gains (since supposedly aero is less important for the rear wheel), will it go faster than 28mm front and rear?
You want the front wheels to be wider to break more air and this has already been accomplished by changing the arc of the tires surface usig varying rim widths. The outer rim width on some newer wheelsets have been wider on the front wheels than on the rear because of this actually (see CRW and Elitewheels Drive) by an insane 5mm (34-29mm) on the CRW cs wheels.
As I've said over 1 year ago: 28c front, 32c in the back and you get it all: comfort + aero
EDIT: it also benefits:
1. Rolling resistance - most of the weight is in the back
2. Aero - the frame-tire gap gets smaller
This would by a good test
I'm with ya!
Business in the front, (comfy) party in the back - the mullet of tire width combos!
trailing edge of rear wheel having a bulge is still bad, but might be worth it depending on the bike/rider/speed
Aero matters much of the time, rolling resistance matters all of the time. It's not a surprise that you could squeeze out a little performance by rolling smoother while deviating from the ideal aero by a bit. What I wonder now is if you tried 5 tire pressures on each of the fastest widths if you could close the gap.
I agree I would love to see different tire pressures on each setup in the next video
We all know what happens when you change tire pressure.
This entire comment is like, "ok?" Lol, the video is about the fastest tire and rim combo, rolling resistance and aero obviously matters here
Also slicks tires have always been a thing
I made a video about tire pressures already, check out the channel!
Silka, SRAM, etc. have already done the work of computing the optimum pressure for a given tire and rim width, rim type, riding conditions (wet, dry, rough, smooth), etc. The seem to recommend the same pressures for the same conditions, so it seems likely they're all pretty accurate. They could each be wrong by the same amount, but it seems a better use of Jeff's time to tackle questions that the calculators don't answer.
@@darrellstyner0001 I'll be the pessimist. You mean how every road tire manufacture, every pro bike team, and pretty much everyone in the industry believed 180 psi and skinny little tires were faster for many decades? I'd rather see a test to add to the body of evidence that we are heading in the correct direction.
Thanks as always! Would love to see that 28 + C50 vs say a 32 on a similarly aero optimized wheelset. Maybe get some aero-ish 29er wheels on haha. I'm doing a build with 32mm wide wheels, can't wait.
I've been running 28 on the front for aero and 32 on the back for comfort. Could be an interesting thing to test?
Tips on putting the tire worked for me, thanks.
How about a mullet set up? Aero in the front, chonkey bois in the back?
Love the videos!
I was wondering the same thing!
I use 28(29mm actual width) front and 30 (31mm actual width) rear tyre combo on ~29mm external width rim and it is soooo much better then 28/28. No testing on my side, but average speed on routine courses is quite similar, yet control is better and fatigue is substantialy lower.
Same question for me. If you tested again with 28mm at front and 30 then 32 at rear, my guess is that you could improve on the straight 28 results. Could well be wrong
3:40 the real goal is to make sure the whole bead of the tire is as deep in the channel in the center of the rim bed as possible. The beads tend to work their way out of the channel and onto the raised flat part of the rim bed and that's the slack needed to get the last part of the bead over the rim.
Great video as always, thanks. +2mm rear tire is also an option - 28mm front/30mm rear or 30mm front/32mm rear depending on rim width. With this set up, you would typically use the same pressure for both tires. Aero concerns are mostly for the front wheel. More rider weight is on the rear wheel. The fatter rear tire should absorb more shock, have better rolling resistance and handle better. The UAE team has used this set up.
Just commented the same thing, my set up is a 28/30. On my TT I run a 25/28 when the roads are smooth.
Hey nice vid and all but maybe do something with the sound balance ?
Music is waaaaaay too lound and speaking segments I could barely hear.
Had to adjust the volume each time which is pretty annoying
That's odd I didn't hear any music, but I'm on drugs currently.
You brought the emphasis of conditioning determines for most part the out come. To many vids place emphasis on equipment over looking how fit you are. Kudos to this video!
So, 2 seconds is your error? I think you are spot on with the comfort. And wide rims are always good. You should do more laps each set-up.
I demand this video be awarded "best video on youtube." If not only for tire mounting tips.
Your standards are obviously very low...!!!
Great follow up to your prior video.
I got the same rims and found that more light bulbing also makes them less stable in side wind so I just use 28mm on them. Didn’t know it was faster.
What a tricky movement it was. Thank you so much I will use it.
Check hollowgram knot 64 with 23tire.
In my opinion one of the fastest wheel for flat roads))
Huge 32mm outer rim width - Helps air flow off a large tyre (26+mm) re-attach more smoothly to the rim, reducing drag. Only possible with disc-only design. Optimized for 23c (26mm) tire but, unlike other wheels, the KNØT 64 design exhibits minimal change with even larger tires, giving riders the option to go bigger without significant aero penalty.
Well done, Jeff. Kudos for the finger strengthening exercise.
Your testing vids are getting better and better, even the process part is now enjoying! You have come this far, why not test different FRONT and REAR tire width next??? We all know the front end is the most crucial part of aero, rear end, not so much. Now that you have established 28mm as the baseline, just try 25 front and 28 rear, 28 front and 32 rear, 25 and 32 rear. See if this could give us some more insights.
Anecdotally I current run 25 mm GP5K TL (the previous version) at front and 28 mm Schwalbe Pro One at rear. My rim is not so wide, I believe they were optimized for 25mm at the time, with 28mm on, I get that little bulge (you can feel it just by run your fingers through), but with 25mm it's smooth and flat, even ever slightly narrower than the rim. Even though that 25 GP5k is somewhere about 8000 km old and at its end of life, my feeling is 25 mm still "seems" faster, and "feels" more stable in the wind. Tires are so expensive now so it's not possible for me to do the test ourselves. We are all looking up to you now, Bro!
You win. You are my favorite bike related channel. Well done!
Glad you mentioned the rule of 105 in this one, that was my question from that last vid, 'Is rolling resistance more important than the rule of 105?' have a set of 30c GP5000s on the way for my Roval Rapides hopefully they work out to being a good balance between the rolling resistance and aerodynamics.
Those 32mm tires snug into the Scott frame really nicely!
Now that you have said that, we want to see the difference between tyre installed in right rotation direction and wrong =)
i have seen people do it with these same tires and it really didn't make any difference which make sense because these specific tires have very little thread and really all the thread it has is mostly just for looks. with tires that have actually functional thread the tire direction makes alot of difference and it is very noticeable.
It might not make a difference in rolling resistance but I'm very certain it will make a difference in grip especially while cornering at high speeds downhill
@@sueghdsifbvjvn I look forward to seeing the results of your test of this theory on your UA-cam channel....
@@oplkfdhgk It makes a significant difference on GP's, because the tread contributes to the low aero drag of the tyre.
@@joebusby1 i can see how that could be real.
Love these comparison vids Jeff - now I need to go measure my outer rim width and I'm already guessing it will mean moving from 25s to 28s.
you'll be shocked at the difference in feel
Would like to know what size frame everyone rides vs their height, similar to your video looking at what tires and stems everyone rides. Maybe could discuss briefly how each person came to their frame size through their bike fit or what worked/didn't work for them.
The one thing that you have not tested is a more narrow aero tire up front and a better rolling wider tire in back. It is simple, aero is more important in the front and rolling resistance is more important in the rear. You should test this.
OK, now show us a mullet set up. 28/30, 30/32, 28/32 so you get some aero on the front, but you get better rolling resistance with the 30+ on the back. I’m rolling 28/30 and love it.
I put 28mm 4seasons on my Elite 25mm deep section rims and the ratio is almost 1:1. I get a nice cushy high volume tyre with skinny aero benefits.
I think you should change to something faster. GP5K vs 4 Seasons, that's the mass gain here. That will offset any of these marginal stuffs. If possible, deeper wheel then. Obviously that's not cost effective but in terms of gain, that will still offset anything about this ratio thing.
@@xuchenglin6256 Yeah agreed 5000s would be fast for track and crit but the roads around here... i need that puncture resistance and assurances for Time trials.
Tx for the helpful video. It would be interesting if you can test it with 30/32mm wide rims and suitable tires, considering many companies are heading there. Then compare the results with the 28mm wide rims
I would also like to see test with 30 mm external width
Love these videos. Something to note. Some wheels taper to the leading edge. Making the middle of the rim wider.
Hey Jeff, I love your videos! I would really like to see one where you test protective equipment. Crashes unfortunately happens in this sport, and I'd like to see whether the additional protection is worth the potential speed loss of wearing that equipment. More than helmets, I've seen collarbone, knee, and elbow protectors, and even body armors!
Jeff, your videos are always great fun. The graph makes it look like the 28mm tire is dramatically faster but in the end it shows a 15 second difference out of a total ride time of 812 seconds? What is the margin of error for this kind of testing? My guess would be more than 15 seconds.
Regarding direction it doesn't make a difference for road bike tires, if you mount them backwards. Schwalbe said in an FAQ that it does not matter and that the arrows are purely decorative
Thats not always true. Thats especially not true for conti gp tires. The tread on gp tires have aerodynamic and water shedding function that certainly do not work in reverse.
If I ran what Silca recommended for tubes I'd have pinch flats left and right. It makes them slower because it's way too low. I ride 95psi with 28mm. Ride feels absolutely fine, and it's fast.
I'm running Bontrager Aeolus Pro 37 (int width 21mm,ext 28mm) with Vittoria Rubino Pro 28 mm tyres at 70 psi for my 80 kg frame. Huge improvement from the 700 x 23 c at 100psi I've been running for most of my riding life! 😂
I watched this video the day it came out, but 2w later I found myself thinking about it again as I was putting on new tires. If you have the ability to do this, Jeff, I think it would be really cool to repeat this while motor pacing at ~30mph to better replicate pack racing. Probably would require multiple runs to insure accurate results of each tire but you could also cut out the 25c.
Man kudo's for the matching frame x kit black to blue outfit.
What you're measuring using vernier caliper isn't diameter, it's width.
Great end message!
I had an interesting thought on a tire's lateral deflection and how that might affect rolling resistance. I'm assuming this would only be an issue when sprinting out of the saddle using increased lateral forces on the bars. Under this scenario, would higher profile tires have higher lateral deflection and would the deflection negatively influence rolling resistance.
Another thought on the higher profile of tires from 25 to 28 to 30s and beyond: If you are using the same power but the tire has a higher profile/ longer runout, won't you be covering more distance vs a lower profile tire.
I have a couch engineers aero theory of which i'm very curious about in real world results. What ive learned about aerodynamics is that you want to attach the airflow in the front and detach airflow at the rear so i run a 28mm up front and a 30mm in the rear for a conscious light bulb effect. PS. 28mm wide rim.
I think I have heard of people doing this before on tt bikes, 23mm front 25mm rear
I believe the air flow is ALREADY turbulent by the time it gets to the rear wheel, so having a more comfortable, lower rolling resistance tire (consistent with the frame, of course) makes sense.
I'm also a couch engineer, but I think the idea is to keep the airflow attached as long as possible, whether in front or in back. This is why aero bikes have deeper sections. Attached air is always good. The light bulb effect is never desirable.
Match the wear indicators with the valve hole so you can find them later! On the Contis they line up with the logo; I don't know if that's true for other tires.
So funny how for decades we ran on 23mm, 21mm, and even 19mm tires without complaint, and now a 25mm tire feels unsafe. Hmmm...'
But yeah, I really like my 28mm tubeless tires & wheels.
First dud I could see would know the correct way to mount a tire. I would only suggest to use both hands at the same time on each half of the wheel to center the tire toward a valve. Just nitpicking. 👍
What I want to see is the following:
- Aero Bike with Aero wheels and your choice of tire
- Ti ( round tubes ) or Aluminum or Steel with the same aero wheels and tire.
That is the comparison you never see, not even GCN is willing to do that comparison.
Can you pls Jeff do this comparison for us?
Thanks
i was surprised you suddenly sent a picture of a Tirich Infinite, which is a bike sold most of the time in selected countries in Asia, but most of the time in the Philippines. costing around 212 dollars when converted, which is considered a low-mid budget for an aero disc bike.
Id love to see some combo setups tested front to rear. I cant see why this wouldn't be the best case?!
25f/28r 25f/30r 28f/30r 28f/32r
when using the psi calc. base it off actual tire width when inflated
correct. watch the video i talk about this.
@@NorCalCycling I'll have to rewatch it, I maybe missed that part.
The Flo wind tunnel study showed that the 105 rule applies at bigger angles of attack. At low angle of attack the advantage of 105 to 100% is negligible. So you might see greater benefits at big windspeeds from the side. I also noticed the silca calculator recommended way higher pressures for 25mm setups than the sram calculator, almost a whole bar more. At 28mm the recommendations are very similar. IMHO silcas recommendation for 25mm is way too high. As a result, your test run might show increased rolling resistance for the 25mm setup.
28mm front and 32mm rear should be the fastest probably. Most of the rolling resistance gains come from the rear wheel. The dura-ace C50 are surprisingly narrow.
I've been searching for the fastest tire and rim combo, but all I found was a vortex of endless bike upgrades! 🚴♂️💨
Thoughts on running 25 front 28 back?
nothank you, 25s feel so harsh and unless you have super narrow rims they will be slower too
3:50 I've changed my tires countless times and am bothered by how easy you made that look. I still have to revert to levers and caveman style grunting 😂 Huge fan of your channel by the way
I got the Shimano C46 (105 version of these wheels). They are so much easier to mount on than my older Mavic and DT Swiss wheels.
what do you think is fastest wheels overall that you've tested. Rovals? DuraAce? Reserve?
Hi Jeff, did you notice any more of an effect from crosswinds with the lightbulb tyre setup? Thanks!
it wasn't particularly windy this day, but yes in general lightbulb is more susceptible to poor crosswind performance
Audio balance on this one is all over. The B roll music is super loud but your speaking sections are super quiet.
Nice video but please have a look at the volume mixing. As a headphone user the music is really really loud compared to the rest of the video.
would 30's on a 105% rim width ratio be faster than 28s on a 105% rim width ratio? I have been looking for wheel set/tyre combination videos/testing for months trying to figure this out.
Sorry but I would expect that ratio would be |tyre-width| / |rim-width| since it looks more like a tear drop which is the best aero shape... in that regard 28mm are closer to the tear drop shape.
That is one thing I don't understand with the tires coming off hookless rims in the world tour. I read that at least one of them was running 25s which is narrower than recomended. Why wouldn't they just run 28s since the rim is so wide. There would be no advantage to 25s at all. And note, I am not debating hookless rims. I am nervous about them myself for road. I am asking about their tire width choice.
so to sum it up:
Go as wide as you can starting at 28mm but try to keep as close to the ratio of 1.05 right?
If higher volume tyres are good then surely a higher volume rider is a good thing. That's my story and I'm sticking to it.
Ya, all of my 240 lbs agrees
I know it was Paris Roubaix but the average speed this year was crazy high so aero is mega important and VDP ran 32mm tyres on the Dura Ace 28mm rims. Wonder what he ran at Amstel Gold?
Hi, I'm a female just getting into racing and your videos have helped me a lot. Thank you!
Tell us how we can get in to these bike races and join in on all the fun of racing
Super informative, thanks! I guess rims are going to be wider as the years go by, so we'll be able to match wider tyres without the aero penalty of neglecting that 105 rule. The pursuit of marginal gains that empties our pockets and keeps the industry up and running 🤪
How about testing a suspension (or Paris Roubaix specific) stem and saddle post compared to regular road stem and saddle post? Can there be any significant aero penalty?
Will try out 28c in the front with a 32c in the back this season. Is it the perfect mix of aero, comfort and rolling resistance? I don't know, I dont care, but I'll have fun riding my bike. 😁
Outside diameter? Or do you mean outside width?
Any way you can test out of your comfort zone? I’m curious about climbing Mt Madonna or a longer climb like Henry Coe. What size tire would be optimal on a climb?
What about different sizes in the front and the rear? It might work pretty nicely to combine 28 front and 30 or even 32 rear. I mean something like fast and comfy… what do you think about it? Is the rear as aerodynamically important as the front (I don't think so)?
Have you considered that basically all measurements could be within the same range, i.e., the impact is much smaller than the uncertainty, and the 28s are just an outlier? There are so many uncontrolled influences that this kind of testing is simply inconclusive.
ya it's possible, but the 25mm test duplicated gave me some reassurance, and so did the consistency between these tests and the tests done with the wider rovals (discussed towards the end of the video)
@@NorCalCycling - great video. My first thought was similar. Nearly all the runs had the same time (within 2 seconds) except 28’s. Was it the tire or the variables … Either way, great job on your videos and congrats on your channel. Actually have a set of Winspace Hyper wheels being delivered today. External width of 28. Sitting here trying to make a decision on tires.
@@NorCalCycling Perhaps to remove such reasonable 'testing' questions in future tests, measure the thickness of the tread on each tire, as this also seriously influences rolling resistance. There are potentially batch and size difference that could create such an outlier. 🤔
It's great you stuck to new versions of different sizes from the same model tire. (Good for me too as I bought 2x 23/25/28/30mm GP5000s to confirm which to use for the rule of 105 for my rim-brake Cervelo.)
ETRTO (& many bike warranties) state that 4mm clearance is required all around the tire in both fork & frame. Does this mean that to combine the rolling resistance with the best aero, always buy the widest rim that will leave 4mm clearance and then select the widest fitted tire that matches the rule of 105 or goes closest, especially at the front?
I saw you on Chris Miller Cycling and follow you here now, too. 👍
Just watched it again. Such great content.
What is the bike model actually? I loved it even I haven't money enough 😅
Great vid. Once you've checked a mullet setup can you check butyl vs TPU?
Vs latex
Hey Jeff, I LOVE these videos, however in this case I fail to draw the same conclusions from the data you have. In order to say 'buy the biggest rim width', you also need to compare a narrow rim with narrow tire setup. At the end of the day you still have two very large trailing edges on the front and rear wheel which consist of the tire (not a particularly aerodynamic trailing edge compared to the rest of the bike), and these are bigger (=more drag) if you have a bigger rim+tire combination.
narrow rim/tire is aero according to rule of 105. wide rim/tire is aero according to rule of 105. but wide also has better rolling resistance, puncture protection, cornering ability, and comfort at the cost of some marginal frontal area and weight, which is not really important unless you're not cornering and racing on fresh pavement or a velodrome.
@@NorCalCycling Agreed, but I'm not convinced that the frontal area difference is marginal when it comes to aero penalty. Though now I recall you may actually have some data from that from a previous video, so I'll go take a look and revisit!
@@NorCalCycling why does wide have better puncture protection?
@@carsonau116 The wide tire has a larger contact patch and can be run at a lower pressure. A sharp object trying to push through such a tire has to push much harder, which makes the tire harder to puncture.
For my TT bike setup I've got Bontrager Aeolus XXX 6 Front wheel which i think has a 21/22mm inner width currently Ive got a 25c GP 5000s on there. Not sure what the outer width is. On the back I have a disc wheel(race setup) with a 28c GP5000s. Not sure about this width at all. My Qs is, do I change the front to 28c or because of the potentially skinny wheel width I keep the 25c on there. Im racing a IM 70.3 this weekend a d want to be as fast as I can.
Width of the tire, not diameter.
Love the videos btw!
What would be your opinion on having say a 28 on the front and a 30 on the rear (with those DA wheels)? Will there be a front/rear difference in the aerodynamic effect vs the bigger volume etc?
How about 30mm external and 28mm tires?
Random inquiry, but are you changing the tubes? I use the Specialized Road Turbo Presta Valve Tube With Talc tubes that say they are for 20-26, I've always run 26s, but now plan to shift up per your findings here. What size / style tubes are you running? Thanks!
for this testing i used tubes for convenience, but since about 2022 i switched to tubeless. you can get away with using 20-26 tubes in 26+ tires it'll just stretch and be more prone to flats.
@@NorCalCycling thank you!
Yet again @norcalcycling you're begging the question.
You can put different width tyres on different wheels. The rear tyre/wheel interface has very little impact on overall drag because it does not have a meaningful leading edge.
The rear wheel contributes the majority of your rolling resistance. Put a wider tyre on the back.
The front wheel contributes the majority of your CdA. Put a narrower / 105 compliant tyre on the front.
On something like the DA C50s, this might be a 25F/30R, on you reserves a 28F/32R.
Thanks for the great content! Curious how you square these results with the results from your "How wide is too wide" video?
The 32s in that test were much faster than the 28s. Obviously key test differences would be test wheelsets (35mm wide Roval Rapide CLX IIs + 28.5mm wide Lun Hypers vs 28mm wide DA C50s), power output, and tire make/model (Vittoria vs Conti). But still, if you were doing some test runs on the Hypers in that previous video, there would've been some tire combos way less aero than the 1.05 rule that were nevertheless significantly faster (i.e., the 32mm tire mounted to the 28.5mm wide Hypers).
Watch this whole video
@@NorCalCycling Got ahead of myself, thanks! So just to clarify, all the data in the "too wide" video are from the Rovals?
As fast as possible, for as cheap as possible👍 That rings true for us at Formula 369!
Im on rim brake my internal is 21 and external 25 and my 30's measures 31.2 so definitely not aero but hard to find wide rim brake wheels
Next vid, comparison between wide rim internal mid depth vs 19mm rim internal deep section.
I wonder if the bigger tire often actually having a bigger RAM(radius as measured) offsets the rule of 105 or something. Essentially adds a few mm of deep dish to your wheel in the form of tire.
I know thats why 3T aero gravel wheels are only 45mm, they say the gravel tires add plenty of depth.
It would interesting to see you do this test at different average speeds. Maybe 20mph avg and then 25 mph avg
we did! check the last video about tire size where we changed average speed
@@NorCalCycling Ok perfect thanks!
Hi , what do you think about quality of dac50 vs roval rapide clx, I had c24 DA and make some best time on my well known rout and change it for clx 40 rapide with ceramic bearings and was slower about 1 km h I dont understant it Thanks
Hello
what was the tested distance? how many km?
How about 28 front and 30 rear with Elitewheels drive 40?
Hey you read my comments and retested! Awesome!
So I guess 30mm is the sweet spot? Just have to get the right size rims. Also what is the cornering difference between 28 and 30mm?
Not necessarily - it depends on the outer width of your wheels. If you have wider wheels like the 35mm wide rovals in the previous video, 32mm tires would be faster.
that 28mm has to be a fluke. possibly you got a little tail wind?
if it was sweetspot of aero and rolling resistance like you said you would likely see a v shaped or reverse bell shaped curve but we don't see that.
Realistically you probably couldn't even do this accurately enough outdoors because the data would probably be too noisy.
I think bike rolling resistance found out that the Vittoria corsa pro speed were the fastest tyres, would definitely give it a go
Not very fast to be repairing a flat on the side of the road 😢
5:00 you refer to it as the tire to rim ratio but it's actually rim to tire ratio
All tire width rides fast
Just remember your body weight will decrease speed
Make the ride slow
Make sure your body weight is low enough if you want to fly at high speeds
putting tires onto a wheel has to the worst experience ever that's why i pay mechanics to do it. And you had to to it about 8 times.... respect