Just One Noisy / Rough Gear

[beancounter]

The 3 largest gears on my Lemond all run smooth and quiet, then the fourth is so rough and noisy I cannot bear to use it, the fifth is slightly noisy and 6 to 10 are again smooth and quiet. Gear changes are fine.

What could be causing the one gear to be so rough and noisy and how do I adjust it without spoiling the others?

Drivetrain is 10 speed campag (chorus mainly) with less than 500 miles.

Many thanks

bc

 

[byegad]

Are the rough gears the ones you use more often? If so the noise is a sign it's time to change the cassette.

 

[andy_wrx]

Not after 500 miles, it shouldn't be...

Have you got Campag 10sp on one of your other bikes ?
- swap wheels : is this wheel (and cassette) just the same on the other bike, or is the other wheel just the same on this bike (and chain, derailleur, etc)