How to fix the shifting on your bike. The majority of rear shifting problems can be solved with basic adjustments to the limit screws and index setting of the rear derailleur system.
source/image(PrtSc): Park Tool
In this video, we’ll show you how to properly set up and adjust your rear derailleur to eliminate rub, noise, slow shifting, and inaccessible gears. Watch the video from Park Tool for more info:
Derailleurs are fitted with limit screws that stop the derailleur from moving too far inward or too far outward. If you look closely as the derailleur moves, you can see the limit screws stopping the derailleur at each end of it’s travel.
The main purpose for the limit screw is to prevent the chain from going into the spokes or into the frame. Tightening the H-limit screw restricts the limit as shown. The goal is to dial it in as close as possible to the inward cog.read more: parktool