Derailleur noise

[jopatco]

Hi Guys

My Cycle Genius recumbent (my first bike - 200 miles) has started making a noise. At first, it was exactly synchronized with the rear wheel - one click (slap? tap? clunk?) per revolution, but then became asynchronous. Coasting or pedalling - didn't matter, but it won't do it on a stand. The bearing seems OK.

The shop says it's because the spring on the Sram 5.0 rear derailleur is weak, allowing the long, un-tensioned chain (without an idler gear) to rock the cassette back and forth, producing the noise.

Does this sound reasonable? Would a new derailleur help? Is this a common problem for bents? Would a jury-rigged idler gear on the chain help? Any suggestions at all???

Thanks in advance for any help you can give this poor dummy,
jopatco

[dfulton]

Could be the dr, could be the chain, could be the cassette, could be the wheel bearings, could be a spoke twanging. You might also just have the dr slightly out of adjustment, is it only in one particular gear? Usually adjustment issues are heard in the bottom (largest) gear on the cassette, most deflection on the dr. If it occurs in a different gear, check the teeth on the cog, a chipped or bent tooth can make the noise. If you have a free couple of hours (like in front of the TV) you can walk each link in the chain to see of one is stiff. This is largely a trial-and-error process of elimination.

Darren

[bnet1]

I had a ticking sound develop in a wheel on a new road bike once after I had it for only a couple of weeks. It turned out there was a small pit on one of the cones in one wheel bearing. Mine made noise whether coasting or pedaling and it progressively got worse over time. Have the LBS check out the rear wheel again. Also listen very carefully to make sure it is the rear wheel.

'bent Brian

[jopatco]

Thanks for the input. I don’t think it’s the chain as sometimes it happens several times before the chain can travel all the way around. And it happens regardless of the gear, rpm or speed. The LBS checked the spokes and the bearing. There doesn’t appear to be any chipped or bent teeth. Tonite, I’m gonna try a rubber band to assist the spring and see if that helps.