A grip shift is a type of bicycle gear shifter. The grip shift is used on flat, mountain bike-style handlebars and works by gripping the side of the shifter and twisting it forward or backward to the desired gear. The grip shift relies on a cable to actuate the derailleur -- the device that directly guides the chain to the selected gear. The cable is replaced if damaged or worn.
Twist the grip shift to the proper gear. The proper gear is determined by which grip shift cable is being replaced. Twist front grip shifts into the smallest gear. Twist rear grip shifts into the largest gear. The gears are numbered on the grip shift.
Open the cable hatch on the grip shift, using the blade of a screwdriver if necessary. The "hatch" is a rubber tab that covers the head of the cable.
Unwind the shifter cable. One end of the cable is bare, while the other end contains a metal fitting. The metal fitting allows this end of the cable to sit inside the grip shift.
Pass the shifter cable into the cable guide in the grip shift. The guide is the hole in the shifter beneath the cable hatch.
Grab the other end of the cable once it emerges from the cable housing on the handlebar. Pull the cable taut.
Pass the cable along the bicycle frame to its derailleur. A front twist grip shift cable goes to a front derailleur; a rear twist grip cable goes to a rear derailleur. There is a derailleur for each set of gears on the bicycle.
Fit the cable beneath the anchor bolt on the derailleur. This bolt secures the shifter cable to the derailleur.
Pull the end of the cable to remove slack. Use a 5mm Allen wrench to tighten the anchor bolt onto the shifter cable.