I have a GT ZuM that I have ridden with no problems for more than 9 months. However, recently the three highest gears(lowest speeds) (this bike has 8 gears) have made lots of noise, especially the highest gear (lowest speed), which doesn't work anymore. The lower 5 gears all work very well with no noise. Anyone know why? Any help would be greatly appreciated. Thanks
It could be your "b" angle adjustment; the jockey pulley on your derailleur may be contacting the sprockets in your higher gears causing the noise. This is a good resource for diagnosing and repairing the problem.