Maintenance/Drivetrain/Vibration through BB

Some experienced opinions on my problem would be very helpful!

I have been having a vibration through my drivetrain and originally thought it was the turbo, but now tested on another turbo and is still there.

So the vibration occurs only in small chaining and generally on the right downstroke, as i put a bit of power through the stroke a shallow vibration goes through the chainring or bottom bracket, its not terrible but sure it is not right, it sort of reverberates at the bottom of the frame, I do not think it is noticeable on the road. this is a new bike with a couple of hundred miles on. It a colnago threadfit 82.5 BB, I am quite hands on with my bike fixing minor things but not ventured into the world of Bottom brackets yet.

Anyone have any ideas as I’d rather not take it to the mechanics, the only people i would trust with it as a distance away, rather jut get it fixed at home and carry on training.

Thanks

If it’s there only under power and on the small chainring, most probably it’s a chain/chainring meshing generated buzz. It the bearings were involved, it would happen all the time. I’d suggest first confirming this by removing the chain and testing the BB alone - including spinning the pedals slowly while standing to load the bearings.

Otherwise, it’s either the chain and/or the chainring. Smaller chainrings tend to have this rough sensation under load more than larger ones, so potentially it’s all ok - hard to say without seeing it.

Thanks for response, just strange when all components are on about 200miles max.

If this video works I think it gives an idea.

Chain off and standing on pedals and turning seems ok, if I give the crank a good spin with hand seems ok maybe touch of friction on drive side.

That’s a 34T, right? Does sound like typical small-chainring high-load buzz to me. Does it vary depending on chainline?

Yes 34, had 36 on old bike, some cogs better than others.

Now wondering if it is my rear mech or hanger I did have a mishap with that a while ago, got some twig caught in there bent my hanger and put mech into spokes, bent hanger back and re indexed and seemed fine out on the road, I had forgotten about it. now it’s wet and cold im inside on the trainer.

If I just turn pedals with hands, chain on and pressure from trainer everything runs in line and smoothly just when I put full load on clipped in I can feel it but on front chain ring.

Derailleur hanger alignment should be verified then, tune the RD, make sure the chain lube is ok, and you should be good to go.

Have you confirmed the chain isn’t rubbing the front derailleur cage? Quite possibly it may not do it when spinning the pedals off the bike but the small amount of frame flex when pedaling under force and/or mounted in the trainer may be just enough to allow the chain to contact a front derailleur that is adjusted slightly too close to the chain line.

I also agree with other remarks about some chainrings causing this noise and find that a good clean and lube of the chain tends to reduce it.

Put the cassette that was on my current wheel onto the trainer so exact same setup as road and that has improved but still noticeable, now just in two middle cogs in the cassette, just happens to be the cogs I would use for all my erg training. I will have to keep adjusting till I get it right.

New hanger and rear mech, still there, different cassette, still there, different chain, still there, different crankset still there, only thing left if bottom bracket :triumph: if I change the bb and still there then I will have wasted a weekend of my life!

Just saw this looking for something else… the Shimano 11-34 11sp is a weird cassette. Do you have the (normally 10sp) spacer behind the cassette? That cassette is 10sp fit, so you need to run the 1.8mm spacer behind it even though it’s 11sp on a 11sp hub. WIthout it, the middle cogs will have some play.

I might have the same issue. I was wondering if you managed to fix yours and, in that case, how? Thanks

I still have it to some degree, I think it’s inherent in using the smaller chainring, if you use large it is fine.

I have found a good lube helps but you put on more and it attracts more dust etc and needs to be cleaned more

Thanks mate. I have a Tacx Neo 2T with a new cassette on. I’m bringing the bike to the bikeshop next week and getting a new chain installed, my bb and rear derailleur checked. hopefully that will help

Hey all @pnecchi @jfranci3 did you manage to find the solution to the problem?

Mine appears under load, mostly on smaller chain rings, but if im climbing uphill I can still get the “rumbling” to appear even on larger chain rings.
Same story here i’ve changed all the following

  • chain ring
  • chain
  • pedals
  • cassete + wheelset
  • rear deraileur

Still getting the same grinding / rumbling issue under certain pedaling load conditions.
It’s annoying as heck!!

Did the BB change help?

Mine seemed to be the SRAM PCX1 (11 speed 1x chain) after trying a few trainers. I probably had 6 different chains come across the trainer I had. I went with a 12sp chain on my 11sp setup and it is much smoother.

On thing you might want to look at, the freehub body. Make sure it’s not all chewed. If it is, take a file to the bumps.

The new chain definitely helped. For the first few weeks with the new chain, the vibration completely disappeared. Now it has come back, but much less than before. Cleaning the chain and putting lube definitely helps. Next thing I’ll try is to properly clean the cassette and the reapply grease to the freehub of the 2T.