Chain Suck...:(
 

Hi all....long time lurker/first time poster.

Anyhow, strange this has been happening with my bike (trek 9700) recently.

I replaced my cranks, chain and rear cassette about a month ago and everything ran smoothly....until.....I replaced my 3 year old shimano xt derailer with a new xt derailer; now whenever I am pedaling at a good rpm in my granny gear chain suck happens.

the only thing I can think of is my chain may be a couple links to short - can this cause it?

any other ideas on what the problem may be?


thanks for any help:)

Well, if you replaced cranks, cassette, and now derailleur and chain all new and to same dimension, it should work fine. If you have wider granny than previous, or larger cranks, then you need a longer chain. Other problems I can think is 1) When you re-attached the chain, two links are stuck together, but then again you would have this problem with the other gears 2) Chain has gook, clean it 3) Derailleur needs adjustment, play with the adjustment screws, or the cable tension needs adjustment. I think problem is likely to be with the derailleur adjustment. Turn bike upside down or mount it on a stand and try to reproduce the problem, looking at the derailleur real close, you should be able to spot the problem. Good luck.

The new derailer is not taking up the chain slack with enough tension to prevent chain suck. Make sure the chainwheel is clean and not too worn, the chain is clean and well lubed and no longer than it needs to be, and try to adjust the rear derailer to increase the chain tension.

I had chain suck a while back, and I think I solved it by removing 2 links from the chain. I had also attempted to solve the problem by changing the derailleur (which is how I ended up with an XTR FD), but that didn't help.

Maybe the jockey wheels need cleaning?