Hey all -

Was riding the road bike on the trainer this evening when I noticed there was a bump once every wheel rotation. The wheel is not rubbing against the stays or brakes so it's not that. It also isn't the speed magnet hitting the frame. It looks like - just maybe - the tire protrudes outwards just slightly at one point, but I think I may be imagining that.

PSI is normal, bike is very new and tires, wheels, etc were LBS installed, for what it's worth. What could the issue be?


Cheers!

One thing to check is whether you have a stiff chain link though this problem generally does not correlate with a noise exactly every wheel rotation. It's easy to inspect, however. Rotate your cranks backwards by hand whilst watching for a hop at the rear derailleur.

Just checked, that doesn't seem to be the case. New chain though, so I'd be pretty irritated if it had a stiff link!

I rode the bike again this AM for half an hour. It's a wind trainer, so I can't hear it while biking, but if I slow down and let the rear wheel spin there is a noticeable "thump" noise once per revolution. I looked closer at the tire and I think its seated fine, but I am still pretty sure it is somehow an interaction between the trainer and tire.

allawayr: Perhaps the thump you are feeling is a joint internal to the tire where the plies overlap, making the tire stiffer at that point. You might not notice it on the road where the contact patch of the tire is fairly extended compared to the trainer which only contacts the tire at basically a single line of contact. Is there a patch on the tire or the tube? It's probably not worth de-mounting the tire to find out, though. Maybe if you ease off on the roller pressure, or increase the tire pressure, you won't notice it as much.

Spin the wheel without the turbo spool in contact and watch the gap between the tire and the brake bridge. See if the distance remains the same. Maybe have a criend pedal the bike slowly while you sit behind and wat h the wheel. Also if possible try another bike on the trainer and see if the bump goes away.

If it bothers you then you will have to de-mount the tire, as it's not practical for us to just guess at what it is. As with any diagnosis you first need to test all the variables. First note about where on the wheel the thump occurs in releationship to the valve stem. Remove the tire and look for any difference in the tube or tire at that point. If you still can't determine the cause mount a different tire (or switch with the front) but keep the tube the same. If the rear still thumps then try a different tube. I would think that should do it.

I just trained for the first time on my trainer and I also hear/feel a slight bump. It could be the bb again (it used to make this horrible clunk, but I took it to the local co-op and fixed it before winter), but I don't think so. It's not bad enough to play "What's That Sound?!"

OK...then why the post?? For the record, the BB would clunk in time with crank revolutions. The OP says his is in time with the wheel.

I posted so that if it gets worse, I can refer back to that post. I can't tell if my clunk is with each wheel rotation or each crank rotation.

Thanks for all of the help guys. I rode the trainer again this evening and it seemed to decrease the thumping by moving the roller a touch further away from the wheel. I did have a look this AM at the wheel while spinning it, and I couldn't see any noticeable change over the course of each revolution in terms of distance from the brake.

I will try remounting the tire tomorrow. Since no one has said that it seems like a big issue, I am less concerned. It isn't really all that irritating, and I can deal with it as long as it's not something that could cause long term damage or something (based off of the responses I would guess not). So I'll probably take off the tire and examine it to satisfy personal curiousity, if anything.


Thanks again! I will report back if I notice anything irregular or getting worse...

Switch to a different wheel and see if the noise goes away.

That would help only if the OP had not already isolated the problem to the rear wheel.