MOUNTAIN BIKE MAINTENANCE: Rear Derailleur
Following is an easy tutorial to tune your mountain bike. If you have any more questions, please contact us.
Before you begin, put your bike in a position so that the rear wheel spins freely (ideally on a bike repair stand, or if you don't have one, then on a bike rack on your car, or turn it upside down)
Shift to the middle chainring on the front and the high gear (smallest gear) on the back.
While slowly turning the pedal, shift the Right Thumb Shifter one click. The chain should move to the next bigger gear on the rear. If it doesn't proceed to Step 3. If it does, then shift the Right Thumb Shifter one more click. Each time you click it, it should move to the next bigger gear. Whenever it doesn't, then proceed to Step 3.
While continuing to pedal, slowly turn the Rear Barrel Adjuster COUNTER-CLOCKWISE until the chain moves to the next gear. After it goes to the next gear, repeat Step 2. (Note: the Front Right Barrel Adjuster located on the cable as it comes out of the Right Shifter can also be used. Both do the same thing.)
That's it! Whenever your rear gears aren't shifting smoothly, this quick adjustment may be necessary. Why do this? All cables tend to stretch as you use them, particularly in the beginning. Cable stretching causes the gears to not shift as smoothly. By turning the Barrel Adjuster COUNTER-CLOCKWISE, it tightens the cable.