General

1. When replacing a gear cable always use a new uncut inner cable. This will make it much easier to thread the cable through the shifter and into the cable housings

2. Always remember to replace the cable inner and outer together; there is no point putting a new cable into an abused old outer.

3. The more you spend on gear cables the better quality they will be, and the longer they will last. Budget cables will need replacing regularly and in the long run is more expensive
 

Fit derailleurs
Remove rear wheel and fasten derailleurs to the bike. Fasten front mech so the base of the outer plate clears the outer chainring by 2mm - the outer cage must run parallel to the outer chainring. Once both mechs are in place fasten the chain. Unscrew, anticlockwise, the barrel adjuster at the shifters and rear mech a few turns before fitting the cables.

Set cable stops
Set the stops on both mechs so the chain runs smoothly. Spin pedals, push the rear mech towards the spokes and adjust the 'L' screw until the top jockey wheel is in line with the largest gear. Then adjust 'H' screw until the jockey wheel is in line with the smallest gear.

Trim cables
Use the old outers to gauge the correct length before you cut your new gear cable. Squirt a small amount of grease into the outers, attach the outer casing caps and fit the outer onto the stops on the frame. Slide the inner gear cables through the shifter and outer casing, pull them taught and attach them at the front and rear mech. Cut off any excess cable.

Index rear mech
Shift into the middle chainring at the front and smallest at the rear. To set the indexing shift into the next gear. If the chain doesn't engage the gear make a quarter, anticlockwise turn at the mech's barrel adjuster. If it over shifts turn the adjuster a quarter clockwise.

Front mech stop low
Shift into the biggest rear sprocket and the smallest chainring. The screw marked 'L' adjusts the clearance between the inner plate of the front mech and the chain. Turn it clockwise to move the mech away from the frame or anticlockwise towards it.

Front mech stop high
Shift into the smallest rear sprocket and largest chainring at the front. Adjust the 'H' screw until the outer plate of the front mech clears the chain as before. Shift up and down to see how the indexing is set, make any adjustments at the barrel adjuster.

Top tip
Setting up the gears for the SRAM twist shifters is essentially the same as for Shimano systems. The only difference with the SRAM units is that the rear mech is missing a barrel adjuster so all adjustments are made at the shifter