Grip shifters are the preferred shifter for many types of mountain bikes. Grip shifters allow the rider to shift comfortably while maintaining a firm grip on the handlebars. This is an important feature when riding over rough terrain containing rocks and roots, or when biking through wooded areas. Over time, wear and tear can damage your derailleur cable and require maintenance or replacement. Having knowledge of this process can save you time and money over taking it to a repair shop.
Shift the front derailleur to the lowest gear possible. Shift the rear derailleur to the highest gear possible. Pedal your bicycle by hand to force the chain onto the correct gears.
Use the wire cutters to cut off the old cable cap from the end of the derailleur wires. Locate the cable caps at the derailleur end of the shifter wires, just past the pinch bolt.
Loosen the pinch bolt on the derailleur by using your crescent wrench or ratchet set to turn the bolt counterclockwise. Do not remove the bolt -- just loosen it until the wire slips out easily. Remove the old cable from the derailleur and the cable housings.
Loosen the brake lever with an Allen wrench by turning the bolt counterclockwise. Slide the brake assembly down the handlebars, towards the gooseneck.
Loosen the bolt on the outside of the grip-shift housing using an Allen wrench until the shifter turns freely on the handlebar. Turn the bolt in a counterclockwise direction, but do not remove it completely. Gently pull the assembly apart.
Slide the old cable out of the shifter. Be aware of how the cable was installed in the shifter housing.
Apply a small amount of grease into the groove that holds the cable. Slide the new cable into the shifter housing. Wrap the cable loosely around the groove once. Slide the cable through the shifter body. Pull the cable tight as you set the cable into the groove.
Push the shifter back together. Test the cable alignment by shifting gears. The shifter should turn normally and click at each gear stop.
Slide the brake lever back to the original position and tighten the screw using an Allen wrench by turning it clockwise.
Rotate the grip shift housing so that the cable is tucked up under the brake lever. Tighten the housing back down using an Allen wrench by turning it clockwise.
Add a few drops of light oil into the cable housings. Feed the new cable through the cable housings on your bicycle.
Feed the cable through the derailleur pinch bolt. Pull the cable taut and tighten the derailleur pinch bolt using a crescent wrench or ratchet set. Tighten the bolt by turning it clockwise.
Use wire cutters to cut the excess cable off 2 inches from the pinch bolt. Apply a new end cap on the shifter wire and pinch down on the cap gently two times with a pair of wire cutters to secure it in place.
Be careful to avoid losing pieces inside the grip-shift housing. Many of the pieces are not secured down and can easily be lost once the housing is open.