Mountain Bike Gears - Setup and Adjusting

All new Shimano gear parts come with setup manuals which are very clear and well laid out explaining how to setup a derailleur and shifters.
 

Gears Setup and Adjustment

Front Deraileur
The front derailleur is the simplest to setup and adjust. There are two setup steps here

Setup Once these setups have been done they should never have to adjusted again unless something breaks or is replaced. Even changing cables will not require these setups to be done again

1: Position on seat tube The front derailleur is fixed to the seat tube and should be parallel with the chain rings. The outer bottom edge of the chain guide should be 1-3 mm above the teeth of the largest chain ring when it shifts over the chain ring.

2: Cable tension With the derailleur all the way down above the small chain ring and the shifter all the way in i.e cable longest, connect the cable, pull tight and tighten screw.

3: Hi and low settings The hi and low settings position the end limits of the derailleur.

With the chain on the small chain ring in the front and large ring at the back the chain should just not touch the inside inner derailleur guide. Adjust the L setting screw to achieve this

Now shift the chain to the big ring on the front and small ring on the back. The chain should just not touch the inside outer derailleur guide. Adjust the H setting screw to achieve this.

Low setting	Hi setting

Adjusting With the derailleur on the middle ring front and back adjust the cable tensioner at the shifter so that the chain is in the middle of the derailleur.

Rear Derailleur

Setup Once these setups have been done they should never have to adjusted again unless something breaks or is replaced. Even changing cables will not require these setups to be done again.

This setup is for a normal type rear derailleur, for a reverse type derailleur the operations will be reversed.

1: Fit to the frame The rear derailleur is connected to the derailleur hanger (dropout) on most mountain bikes.

2: Hi Lo set screws This is best setup with the chain removed and the cable not attached as it allows proper alignment of the top and bottom settings for the derailleur. Use the L (low gear) screw to adjust the derailleur to be lined up with the biggest gear on the cassette. Use the H (high gear) screw to adjust the derailleur to be lined up with the outer edge of the smallest gear on the cassette.

Low setting	Hi setting

3: B-tension The B-tension screw on the back of the derailleur sets the tension of the derailleur and the resulting gap between the pulley wheel and cassette. Set this up with the chain on the small chain ring(front) and large sprocket (back), and then the small sprocket (back). The guide pulley should just not touch the sprocket. This is often preset and seldom needs to be set, and almost never needs to be reset.

4: Cable tension Make sure that the shifter is in the correct position with no pull on the cable (in the high position), then tension the cable and tighten the cable bolt on the derailleur.

Adjusting If setup properly there should be no need for this adjustment. With the chain on the middle chain ring and the second smallest gear on the cassette you can check the cable tension. The chain should shift easily up and down from this gear. If it does not shift up then tighten the cable at the barrel adjuster (turn anticlockwise), or loosen (turn clockwise)if it does not shift down. Only make small adjustments, ¼ turn at a time, then shift a few times to test.

Gear Shifting Problems
Gear and Brake Cable Fitting

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