Do you have an MTB-Tech-related question for us here at GMBN Tech? Use the hashtag #AskGMBNTech with your comment for a chance to be featured on the channel! 👇
I have a Manitou Supernova that I got cheap with a short steerer. At the time, I worked at a machine shop where I made a new one out of 7071 alloy that was extra thick at the bottom and about a 3-5 thousandths interference fit. I pressed the old one out and the new one in on the hydraulic press and never looked back. It heald up to years of trials, street and dirt jumping and has never creaked.
I was taught to make the steer tube long and put spacers on top so if I wanted to sell the fork only it would work on a bigger frame than what I have which is pretty small. Looks funny but it works.
Anna didn't quite understand a question about the copper paste with the brake pads. Most service channels on youtube do actually put a tiny bit of copper paste BEHIND brake pads to prevent seizing pistons with the pads, it eases the next service too.
Our local bike shops that service forks also offer steerer tube replacement, so it's not really a problem if you cut it too short albeit costly, it beats buying a new fork.
Is that in the UK or U.S ? I could not find anyone that offers that service anywhere in the U.S I almost want to purchase a press a learn to do that myself as a service.
No problem to replace a steerer tube, there are some companies that could replace it. But it will cost some money of course, 100-150€ in Germany. (MRC Trading)
I did that, cut the tube too short by about an inch on my new $975 RockShox SID. AHHAAAAAAA!!! Sent it in and had a new tube installed. That cost $350.
Regarding the mullet question. 29er front on 27.5 bike will be more expensive. but you can select a fork length to get/keep your desired geometry. Putting a 27.5 on the rear of a 29er will not only definitely slacken the head angle but lower the Bottom Bracket. and could mean much more likely to experience pedal strikes. So changing the front is better, but more expensive.
My rule of thumb at this point is to have at least 10mm or so above your stem so you can adjust if needed but also to get crucial clamping strength on the steerer tube. The top cap and bolt is for bearing preload only its not the area that protects against shearing loads and catastrophic failure. But what do I know just a dumb yank. Kidding just a little argy bargy love your videos.
I'm about to crop my mtb steerer and I'll be making it flush with the top of the stem for this very reason. Concave top cap won't work, so I'm getting a custom top cap printed.
I'm about to crop my mtb steerer and I'll be making it flush with the top of the stem for this very reason. Concave top cap won't work, so I'm getting a custom top cap printed.
Regarding the rusted brake pad backing plates I think they just ment the piston side of the pads... in which case you could lightly sand the rust off, wipe them down with methylated spirit (the purple stuff) and with the the pad material facing down coat the back of the pads with spray paint.... or just replace the pads.
About second topic. I have spec 2021 with HG body with full Sram GX. As casette I use high end ZTTO (mill from one piece) the shifting is the sam as with NX/SX casette. After one chain it still hold up pretty well.
Bent my shimano brake lever so applied a little heat and bent it back and got a bonus of a black lever fading to copper at the end looks good now I have other side to do
Recently my pad fell apart due to rust. It wasn't bad, what looked like a little bit on the metal part with pad looking good. Then after long downhill the resin pad fell out and I was left with no front brakes. Now I replace them regular, even if they seem fine.
#AskGMBNTech Why hasn't any derailleur manufacturer or even a custom fabrication experimented with an upside down derailleur as a solution to keeping the derailleur safe from rocks and stuff? And what complications would arise from using such a setup??
The derailleur has to feed the chain into the cassette in order to shift (that's why you can't shift gears while pedalling backwards), but the top side is where the chain is feeding out. Now if we made pedalling backwards the norm, and the hub had gears inside of it to flip the rotation around, then the derailleur could be up top.
I had a spill which somehow popped the brake lever's connecting rod out of the piston. The local bike shop managed to push it back in, but it's had extra play in it ever since that the reach adjustment can't fix. I really should replace it one day...
What I want to know is WHEN are they going to come up with brake rotors that don't squeal, bark, howl when wet? Cars use disc brakes they don;t howl when wet, is it because the bike rotor is so thin that there is nothing anyone can do, and if so would thicker rotors resolve the issue? I woul put up with a bit more weight (even double triple and more) to stop the wet howl.
#askgmbntech how does bar pitch/roll affect riding character in details ? I know it’s commonly answered ‘personal preference’ but I believe it’s a highly underestimated factor when it comes to steering.
NEVER put copper grease (or any other) anywhere near caliper pistons, especially dot fluid brakes, as it will damage the piston seals, plus it could get on disc or pads.
#askgmbntech Hi guys. I just got my forks serviced by my local bike shop and it is working fine now. I understand and appreciate the need to regularly service your bike components especially moving parts such forks and shocks. My question is and correct me if I'm wrong, motorcycle forks and shocks especially motorcross bikes don't have anywhere near the kind of regular service intervals as mtb suspension components. How come mtb suspension manufacturers don't build their components like the their motorcross counterparts, i.e. sturdier and require less servicing or overhaul maintenance?
Can the SRAM 12 speed grip shifter pull the shimano 12s RD? There are some discussion about the shimano 12s shifter pull the SRAM 12s RD, but no vice versa.
#AskGMBNTech . I purchased a set of forks from eBay that had a short steerer tube. After researching local businesses to see if I could get the steerer tube replaced I drew a blank. Gutted. As I am an engineer I decided to purchase a 6 ton bench press and bought a new steerer tube so I could do the job myself. I am pleased to report my bike has a new set of forks with the correct size steerer. Costs including new steerer, material to make plates to hold the forks and the press were around £150. If anyone in the UK West country requires this job to be done, please feel free to point them in my direction. This may be the start of a new business?????!
#askgmbntech Hi, thanks for answering. Is there any point to switch to bigger brake disc, 160 to 180 or 203, let's say, without changing the braking unit, for bigger braking power (less force by finger, less braking distance, etc.)?
#AskGMBNTech Hi Anna & Doddy, A question on brakes for your bike tech surgery. I recently (less than weeks ago) had new SRAM Code RSC Brakes installed to replace the original Guide RE's instakked on my Mega, and the stroke length on the front and rear is not even when pulling the levers. The Front (Right) lever almost draws right to grip. Does this indicate the fluid level is perhaps not sufficient? I see no evidence of a leak and cannot adjust the stroke dial any more to compensate. Should they be bled and the hydraulic fluid topped up a bit? Thanks.
#AskGMBNTech Hi there, I have a 2014 Specialized Demo and I was wondering what kind of chain guide goes with that frame (like ISCG 05 or any other kind) and if the BB affects anything on the guide. Thanks, love the show
#askgmbntech Swapping cranksets. I have a dirt jumper with a single speed 135mm rear axle and 73mm bb. It has a 52mm chainline. When I asked a few bike shops their answers aren’t confidence inspiring. They have said to get non boost because it’s 135mm rear hub and but as I researched I think boost with 3mm offset to get the 52mm chain line sounds like the right answer. Any help?
Another top episode 👍- I know I should probably just not be bothered, but it does feel like the whole Mullet bike message is being lost on the general public - with that in mind #askgmbntech is there actually an example of standard 29 or 27.5 bike which converts to a mullet without any significant geometry sacrifices? i.e. you don't have to change a linkage or mess with any flip chips? - my concern is that there are riders out there who are just swapping wheels and thinking they are now 'on trend', when in fact they have just made their bikes ride worse...
A 27.5 is just smaller than a 29. Of course there will always be a geometry change when the bike is mulletted. I think some 29er bikes are designed to still have good geo when the back wheel is changed. But you can see why it is just more common to need a flip - so that geometry is persevered when a wheel is made smaller. I guess on a 27.5, getting a 29er fork with a bit less travel could make a good mullet especially with good measurements, the geometry could be preserved. But it probably won't be universally a good idea as u still want the front travel the same or more than back travel.
All freehub bodies and freewheels can be removed... Some easier than others... Its purely a question of whether the hub manufacturer makes a relevant sram/shimano freehub body for that hub or not
Hi Guys, I'm upgrading my sons bike with my old bits and getting him a new cassette just wondering if the Shimano SLX RD-M675 is a medium cage or long cage. Subject to where I get him 36t or 42t cassette, as it only says RD-M675 VIA (which is stamped in to the metal part of the derailleur) #AskGMBNTech
The bike shop said my fork steerer was too short, after THEY cut it. So I bought a shorter stack stem and everything was fine. Did not go back to those clowns again.
The top of the star nut should be at a depth of between 12/15mm Outside these measurements its likely to kill you but setting it at 2-3 mm isn't recommended
Absolutly, even more if you put the cap directly on your stem, the clamping will be compromise. I think you should always have a small spacer on top of your stem.
@@jonathanzappala exactly right, typically 2-3 mm is spec'ed by mfr from top of steertube to topcap. and depending on stem a top spacer might be recommended.
If your steerer tube is short by a few millimetres you could try and source a stem with a lower stack hight. (I had the opposite problem……I found the new, beefier, stem was too tall for my steerer tube.) Really annoying background ‘music’…….please stop it! 14:30
Do you have an MTB-Tech-related question for us here at GMBN Tech? Use the hashtag #AskGMBNTech with your comment for a chance to be featured on the channel! 👇
I have a Manitou Supernova that I got cheap with a short steerer. At the time, I worked at a machine shop where I made a new one out of 7071 alloy that was extra thick at the bottom and about a 3-5 thousandths interference fit. I pressed the old one out and the new one in on the hydraulic press and never looked back. It heald up to years of trials, street and dirt jumping and has never creaked.
I was taught to make the steer tube long and put spacers on top so if I wanted to sell the fork only it would work on a bigger frame than what I have which is pretty small. Looks funny but it works.
this
I don't mind looking funny I'd rather sell it if I don't like it.
Smells like broke people in here
Anna didn't quite understand a question about the copper paste with the brake pads. Most service channels on youtube do actually put a tiny bit of copper paste BEHIND brake pads to prevent seizing pistons with the pads, it eases the next service too.
But it's been shown many times to be a waste of time.
Aren't the piston ends ceramic?
My Shimano XT sure are.
Also generally used with car brakes.
@@perjensen1962 that's right, but car brake pads will stay in there typically for longer and it is also done to avoid squeeking
@@simonm1447 exactly, its done to mask pad chatter which squeals.
The guys question was how do I cover up the rust
Our local bike shops that service forks also offer steerer tube replacement, so it's not really a problem if you cut it too short albeit costly, it beats buying a new fork.
For sure. It's always worth getting your steerer replaced or a whole new CSU in fact. 👍
Is that in the UK or U.S ? I could not find anyone that offers that service anywhere in the U.S I almost want to purchase a press a learn to do that myself as a service.
you could also get a higher rise handlebar, lose a spacer or two under the stem thus freeing up more steerer to clamp to.
No problem to replace a steerer tube, there are some companies that could replace it. But it will cost some money of course, 100-150€ in Germany. (MRC Trading)
What happens? You have to waste your money on a second new fork is what happens. Lol Measure twice cut once.
yep... or a new CSU
Sell it to someone shorter 😭
She literally says what. Go to a bike shop and they can be replaced.
There are a few places dotted around that will fit a new steerer tube or you can even buy a new CSU. 👍
Bro didn’t watch the video 💀
I did that, cut the tube too short by about an inch on my new $975 RockShox SID. AHHAAAAAAA!!! Sent it in and had a new tube installed. That cost $350.
Regarding the mullet question.
29er front on 27.5 bike will be more expensive. but you can select a fork length to get/keep your desired geometry.
Putting a 27.5 on the rear of a 29er will not only definitely slacken the head angle but lower the Bottom Bracket. and could mean much more likely to experience pedal strikes.
So changing the front is better, but more expensive.
good stuff, love watching these tech vids. thanks for all the good advice.. and enhanced viewing pleasure
My rule of thumb at this point is to have at least 10mm or so above your stem so you can adjust if needed but also to get crucial clamping strength on the steerer tube. The top cap and bolt is for bearing preload only its not the area that protects against shearing loads and catastrophic failure. But what do I know just a dumb yank. Kidding just a little argy bargy love your videos.
I'm about to crop my mtb steerer and I'll be making it flush with the top of the stem for this very reason. Concave top cap won't work, so I'm getting a custom top cap printed.
I'm about to crop my mtb steerer and I'll be making it flush with the top of the stem for this very reason. Concave top cap won't work, so I'm getting a custom top cap printed.
Regarding the rusted brake pad backing plates I think they just ment the piston side of the pads... in which case you could lightly sand the rust off, wipe them down with methylated spirit (the purple stuff) and with the the pad material facing down coat the back of the pads with spray paint.... or just replace the pads.
About second topic. I have spec 2021 with HG body with full Sram GX. As casette I use high end ZTTO (mill from one piece) the shifting is the sam as with NX/SX casette. After one chain it still hold up pretty well.
Is Doddy alive?😄
Quite a few companies (like FSA) make low stack height stems with significantly thinner clamping areas, rhat could be enough to clamp a short steerer
Easily replaced. Rsf in Plymouth will do it.
yeah, he's really good, also does stanchion replacements
Bent my shimano brake lever so applied a little heat and bent it back and got a bonus of a black lever fading to copper at the end looks good now I have other side to do
Recently my pad fell apart due to rust. It wasn't bad, what looked like a little bit on the metal part with pad looking good. Then after long downhill the resin pad fell out and I was left with no front brakes. Now I replace them regular, even if they seem fine.
Regarding headtube what about welding?
What about fitting a reduced height stem??
I was thinking no reason companies could offer a screw in stem no reason a stem could not be threaded.
#AskGMBNTech Why hasn't any derailleur manufacturer or even a custom fabrication experimented with an upside down derailleur as a solution to keeping the derailleur safe from rocks and stuff?
And what complications would arise from using such a setup??
The derailleur has to feed the chain into the cassette in order to shift (that's why you can't shift gears while pedalling backwards), but the top side is where the chain is feeding out. Now if we made pedalling backwards the norm, and the hub had gears inside of it to flip the rotation around, then the derailleur could be up top.
@@KevinT3141 thanks man
I had a spill which somehow popped the brake lever's connecting rod out of the piston. The local bike shop managed to push it back in, but it's had extra play in it ever since that the reach adjustment can't fix. I really should replace it one day...
What I want to know is WHEN are they going to come up with brake rotors that don't squeal, bark, howl when wet? Cars use disc brakes they don;t howl when wet, is it because the bike rotor is so thin that there is nothing anyone can do, and if so would thicker rotors resolve the issue? I woul put up with a bit more weight (even double triple and more) to stop the wet howl.
#askgmbntech how does bar pitch/roll affect riding character in details ? I know it’s commonly answered ‘personal preference’ but I believe it’s a highly underestimated factor when it comes to steering.
NEVER put copper grease (or any other) anywhere near caliper pistons, especially dot fluid brakes, as it will damage the piston seals, plus it could get on disc or pads.
#askgmbntech where is Doddy??
lol
Love that you also use “sub optimal” 😍
#askgmbntech Hi guys. I just got my forks serviced by my local bike shop and it is working fine now. I understand and appreciate the need to regularly service your bike components especially moving parts such forks and shocks. My question is and correct me if I'm wrong, motorcycle forks and shocks especially motorcross bikes don't have anywhere near the kind of regular service intervals as mtb suspension components. How come mtb suspension manufacturers don't build their components like the their motorcross counterparts, i.e. sturdier and require less servicing or overhaul maintenance?
Can the SRAM 12 speed grip shifter pull the shimano 12s RD? There are some discussion about the shimano 12s shifter pull the SRAM 12s RD, but no vice versa.
If your levers are aluminum you should probably replace it, aluminum doesn't bend back and forth well.
If it's steel, ride on
What happens if you "bake" the pads and rotors in an oven?
#AskGMBNTech . I purchased a set of forks from eBay that had a short steerer tube. After researching local businesses to see if I could get the steerer tube replaced I drew a blank. Gutted. As I am an engineer I decided to purchase a 6 ton bench press and bought a new steerer tube so I could do the job myself. I am pleased to report my bike has a new set of forks with the correct size steerer. Costs including new steerer, material to make plates to hold the forks and the press were around £150. If anyone in the UK West country requires this job to be done, please feel free to point them in my direction. This may be the start of a new business?????!
#askgmbntech Hi, thanks for answering. Is there any point to switch to bigger brake disc, 160 to 180 or 203, let's say, without changing the braking unit, for bigger braking power (less force by finger, less braking distance, etc.)?
Bigger discs dissipate heat better.
Doddy already did a whole video on this subject with Magura
#AskGMBNTech Hi Anna & Doddy, A question on brakes for your bike tech surgery. I recently (less than weeks ago) had new SRAM Code RSC Brakes installed to replace the original Guide RE's instakked on my Mega, and the stroke length on the front and rear is not even when pulling the levers. The Front (Right) lever almost draws right to grip. Does this indicate the fluid level is perhaps not sufficient? I see no evidence of a leak and cannot adjust the stroke dial any more to compensate. Should they be bled and the hydraulic fluid topped up a bit? Thanks.
Yes it needs a bleed
OOOOrrr...
you could get a stem with a shorter stack
and get that space back for absolutely no stress?
#AskGMBNTech
Hi there, I have a 2014 Specialized Demo and I was wondering what kind of chain guide goes with that frame (like ISCG 05 or any other kind) and if the BB affects anything on the guide. Thanks, love the show
#askgmbntech Swapping cranksets. I have a dirt jumper with a single speed 135mm rear axle and 73mm bb. It has a 52mm chainline. When I asked a few bike shops their answers aren’t confidence inspiring. They have said to get non boost because it’s 135mm rear hub and but as I researched I think boost with 3mm offset to get the 52mm chain line sounds like the right answer. Any help?
#askGMBNtech Is it possible to reduce rear travel on a full sus by simply swapping let’s say a 210x55 to a 210x50 sized damper?
Another top episode 👍- I know I should probably just not be bothered, but it does feel like the whole Mullet bike message is being lost on the general public - with that in mind #askgmbntech is there actually an example of standard 29 or 27.5 bike which converts to a mullet without any significant geometry sacrifices? i.e. you don't have to change a linkage or mess with any flip chips? - my concern is that there are riders out there who are just swapping wheels and thinking they are now 'on trend', when in fact they have just made their bikes ride worse...
A 27.5 is just smaller than a 29. Of course there will always be a geometry change when the bike is mulletted. I think some 29er bikes are designed to still have good geo when the back wheel is changed. But you can see why it is just more common to need a flip - so that geometry is persevered when a wheel is made smaller. I guess on a 27.5, getting a 29er fork with a bit less travel could make a good mullet especially with good measurements, the geometry could be preserved. But it probably won't be universally a good idea as u still want the front travel the same or more than back travel.
That will be great opportunity to buy better (stronger and lighter) steer tube.
All freehub bodies and freewheels can be removed... Some easier than others... Its purely a question of whether the hub manufacturer makes a relevant sram/shimano freehub body for that hub or not
Any machinist/millwright worth his salt can easily repair a set of forks, but cost of repair should never outweigh the cost of new.
Time for a new csu
Can water contaminate your rotors. Also if I use dilated soap and water and accidentally get it on my disc will it contaminate it #askgmbntech
Hi Guys, I'm upgrading my sons bike with my old bits and getting him a new cassette just wondering if the Shimano SLX RD-M675 is a medium cage or long cage. Subject to where I get him 36t or 42t cassette, as it only says RD-M675 VIA (which is stamped in to the metal part of the derailleur) #AskGMBNTech
The bike shop said my fork steerer was too short, after THEY cut it. So I bought a shorter stack stem and everything was fine. Did not go back to those clowns again.
The answer is replace it, save you watching 😅
#AskGMBNTech Hi guys, will Ohlins 36 RFX 160mm 29" Forks Fit My Evil Wreckoning 29" Boost Frame ?
5mm is big, 2-3 is more like it.
The top of the star nut should be at a depth of between 12/15mm
Outside these measurements its likely to kill you but setting it at 2-3 mm isn't recommended
Absolutly, even more if you put the cap directly on your stem, the clamping will be compromise. I think you should always have a small spacer on top of your stem.
@@knott4me561 were not talking about the star nut depth were talking about the length of the steer tube.
@@jonathanzappala exactly right, typically 2-3 mm is spec'ed by mfr from top of steertube to topcap. and depending on stem a top spacer might be recommended.
where is Doddy?!
Imagine cutting ur steerer tube to short💀
Just tell her it's cold out because when summer comes she's gonna complain that it's too long now
Snap the top of the steerer.. yeah I don't think so.
If your steerer tube is short by a few millimetres you could try and source a stem with a lower stack hight. (I had the opposite problem……I found the new, beefier, stem was too tall for my steerer tube.)
Really annoying background ‘music’…….please stop it! 14:30
Catastrophic Failure 🙈
afternoon
How many she sayed "ERMM" is unreal
tighten enough to hold but it should move some if you hit it with your palm. you want give for that reason.