Bicycle Mechanics - Clunk with every pedal revolution

I have a trek oclv frame with DA 10 components. I have developed a resonating “clunk” with almost every pedal revolution and always at the top of the pedal stroke. I know it is not the following: Seat (happens both while sitting and standing), a cassette problems because it occurs with both my wheelsets with different cassettes, headset- it is secure, pedals- I have changed them and it still occurs, FD- not rubbing. I guess it could be a tight chain link, but it does not seem likely. The only thing I have not done is take off the crank, but I did check the chain ring bolts and they are tight. Any Ideas? I am not used to the new hollowteck DA crankset and I am wondering if it has something to do with that?

Thanks

JD

If you get off the bike and lightly spin the cranks forward and backward, does it still make the same noise, or is it only under the load of pedaling? If it's the former, I'd look at the chain. If it's the latter, I'd look at the bottom bracket or cranks.

Mine was making the same noise under load, and simply tightening a crank bolt eliminated it.

Is your crankarm hitting your kickstand? ;)

If it's not the kickstand check your knee -;)

Joe

"I have developed a resonating “clunk” with almost every pedal revolution and always at the top of the pedal stroke."

Recently happened to me on a new Trek after about a week...it was a tight chain link.

which crank bolts. I checked the two on the crankarm on the nondrive side? Is this what you are talking about?

was the tight chain link doing that with every revolution and where was it hanging up?

Could be a bottom bracket problem.

Rule1 , dont attempt to ride an expensive big liek that with clunking nosies,thoes da20 are so smooth , you know it has to be a probem. get off the bike and hold up rear wheel and pedal with ur hand . locate the noise. watch the chain. flick thru the gears , does it do it in every gear? if its a tight link, u can tell cos the link doesnt bend properly. have u taken your chain off ? has it always done this?. just go theu the typical prouble shooting methods, to come to an answer. do u have a sensor on ur pedal for cadence? cos that normallywill rub and clunk. anyways hope this helps a lil bit, take care

seems to me that if its related to pedal position in the stroke it has to be in the bottom bracket, cranks, chainring(s) or pedal. I'm having trouble imagining how it could be the chain or a specific link, because each link will be in a different spot on every crank revolution.

Also check the pedal at the bottom of the stroke...

>>seems to me that if its related to pedal position in the stroke it has to be in the bottom bracket, cranks, chainring(s) or pedal

That's what I would think, too. Once-per-revolution noises are usually in the front end of the drivetrain.

Rather than just tightening the crank bolts, I would suggest pulling the crankarms and re-seating them. And while they're off, spin the BB axle with your fingers, and check for bearing play - if the problem is in there, you'll feel it a lot easier that way.

Is this a clunk that you can feel, or do you just hear it?

Upon review, I can imagine a chain-related noise. If the chainring is bent or misaligned, the chain sideplates can catch on an errant / outward tooth & ride up. Under stress it slips into place with a clunk.

Something to check anyway.

well, i agree . take the chain off and spin the crank arms. i woud like to say its the bb, but you just cant deduce that from here, it still could be something in contact.

I had a similar problem. Re-packed the bb -- took two tries, but the problem went away. The lbs said that Trek doesn't always assemble it w/ enough grease.

Was there any resolution of this?

I am having a similar problem - it really feels as though something is brushing on each revolution (right, like the crank hitting on the kickstand), but there seems to be plenty of clearance. It's not major, but enough to be annoying. Seems to be there on both chainrings, although sometimes it goes away. Seems a little more likely when mashing. Never happened until a couple of weeks ago.

I only have about 2-2.5K miles on the BB, so I'd be surprised if that was it, but I'm open to suggestions (I have yet to look really closely and tighten the bolts - I'll try that tonight).

Make sure the pedals are on the crank arm tight enough - they may rotate if they are loose.