Skipping in highest gear

[Hydra]

I thought I'd fixed this problem with some less-than professional derailleur fettling.

Basically, what happens, is when I'm pounding down a hill in top gear (12-50) the chain jumps every so often, like it's trying to change gear. It only happens when I'm pedalling, and only in my biggest gear.

As far as I can tell when the bikes up in the workstand, the gears are tuned almost to perfection.

Any ideas folks? It's taking the pleasure out of those fast descents

 

[amaferanga]

Probably need to back the limit screw off a fraction.

 

[steve52]

Probably need to back the limit screw off a fraction.

=1

 

[Hydra]

Aha, I neglected to think about the limit screws. I shall give that a try this evening.

 

[byegad]

More likely to be the b screw, if the chain isn't wrapped around enough of the top gear it'll skip when you give it some stick and hit a small bump. If your bike has a few miles on it and you use the smallest cog at the rear a lot, it could be worn out. But my first try would be the b screw.

 

[Lard Armstrong]

Check the B and H screws after checking the cable tension (guideline : release the tension in the cable).

This is easy to fix, check parktool http://www.parktool.com/blog/repair-help for detailed advice.

LA