loty

Hi, I have 2009 Specialized Rockhopper basic model that I bought new few months ago and maybe put a little more than 300 miles on it so far. Here is the story - I installed clipless pedals last week and as I never before rode clipless I fell with the bike a few times when stopping because I couldn't get my feet unclipped in time - I guess it's a rite of passage. So anyway, after the last fall my rear deraileur started acting up. Every few minutes or so my gear would jump to a higher one and then jump back. I can't figure out exactly when it happens or what makes it happen - it happens intermittently every few, sometimes up to 5 minutes, sometimes when I push hard, sometimes when I barely push on pedals.

Any ideas what might the problem be and how to fix it?

fietsbob

A Fall suggests you bent the RD mount on the frame, go to your LBS and have that checked.
Index allignment tool required, bike shops have them.
ramps on face of next larger cog will pick up the chain, your index click is not centered over the cog so needs adjustment,
maybe just the a cable adjustment with that housing screw on the brake/shift lever and RD in itself.
they are fussy about that dropout eye allignment, get that checked first.

chain may have a tight , dry , link too ..

serra

It might be loose. I'm not sure how falling would loosen it, but check that it's secured to the frame properly. Lots of things cause gear jumps, but I can't think of any that don't happen constantly while your pedaling. Intermittently is just weird.

loty

Thanks guys. I found some good articles on rear derailleurs (sheldon brown and others) and will try to see what's going on with it tonight. If I still can't figure it out a trip to my LBS will be in order.