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Help identify this 'noise'(7 posts)

Help identify this 'noise'Ryan
Apr 11, 2001 6:28 AM
Alright, some of you here are experts at identifying a problem, so here are my symptoms:

I have a full DA equipped steel frame. Recently (last 2 rides), I've felt a thump on every other pedal stroke. Moreover, I can 'feel' it more on my right foot than my left. If I completely concentrate on my spin, the thump fades away. But, if I let up at all on the spinning, it returns.

I've torqued down the pedals but that's all as far as trying to silence the thump.

Any ideas as to what's out of adjustment? My guess is the infamous DA bb is acting up, but that's just a guess.
re: Help identify this 'noise'Puffer
Apr 11, 2001 6:45 AM
Sounds to me like your guess is probably right - bearing breaking down on one side of the BB - when you spin "better", you place less off-centre force on it, hence the lessing of the noise/feeling.
Same problem, different transmissionIxnixit
Apr 11, 2001 6:53 AM
Me too, every 2nd rotation. Faint thump, in my case worse in the middle cogs and much less on the small ring. If I really think about my stroke, it gets lighter. Difference is mine is Campy Chorus. My reasoning was somewhat different - I figured since it was every second rotation and not every rotation it would have to do with the chain and its interaction with the cogs, not something that rotates equally with each stroke like the BB. Of course, my reasoning might be flawed. And no, I have not yet figured it out.
I know what your problem is....Tsunami
Apr 11, 2001 4:01 PM
I had this same problem about 3 weeks ago. I too felt a clunk every other pedal stroke. I tightened everything, the pedals, crank, and even the BB, but still the clunking persisted. Then I got advice fom this board.

Your problem is that the permalink on your campy chain is about to give. Check it out and you will see that it is loose and may fail soon.

Since I did not have a campy chain tool, I took the chain apart at a regular link. Since I had an early ride the next day and I had an extra SRAM 9 speed chain, I put the 9 speed SRAM on my Campy transmission. I noticed that when I placed the chain in between the middle of the 3 smallest cogs, I still had some play. Not as much play as with the campy 10-speed chain, but still the tolerence was not that much difference. Shifting with the SRAM chain was smooth and almost as good the Campy chain (barely noticable). I used this set-up for about 2 weeks up until a couple of days ago because I got some extra campy links from my friend, and for my own piece of mind, I put the Campy chain back on. Except this time, I used the SRAM Powerlink in place of the Permalink.

Another alternative is to just use a normal campy link and press it in to make a endless chain, thats what I did when installing the extra links that I got. But intstead of pressing in another campy link, I used the SRAM Powerlink. For the 2 weeks (about 150 miles) that I did use the SRAM chain though, the cogs and chain rings did not seem to have any excessive wear.

Mike
Thanks!Ixnixit
Apr 11, 2001 7:28 PM
I had a suspicion that it was the perma link. I'll go check it out.
it could be other thingsjohn de
Apr 11, 2001 7:05 AM
when you let up on the spinning and start to crank alot of things feel pressure..ive had a similar experience and it was two things..the seat (i cleaned the rails and tightened) and the front skewer didnt work well and creaked when i swayed from side to side out of the saddle...ive though about how to isolate creaks which are hard to pin point and i was going to hook up a stethiscope like contraption using a hollow tube and cup...
every other rpm = chainclub
Apr 12, 2001 5:24 AM
something's awry with the chain. a noise every other rpm is the classic tipoff, look for busted bushings or other damage.