How to Replace the Shifter Cable on a Shimano 105
A Shimano 105 is a bicycle gear shifter designed for a road bike. The shifter incorporates two cables, one that operates the brake and one that controls the derailleur. The derailleur is the mechanism that moves the chain to a given sprocket. The derailleur cable is also known as a shifter cable. Generally, shifter cables are replaced as part of a yearly tune-up or if the cable is frayed or damaged at any point.
Shimano 105 Shifter Cable Removal
Take the bike for a short ride and shift into the gear that gives the shifter cable maximum slack. For the front gear shifter, maximum cable slack corresponds with the lowest gear. For the rear gear shifter, maximum cable slack equals the largest gear.
Loosen the bolt on the derailleur that secures the shifter cable with a 5-mm hex wrench. The shifter cable is attached at one end to the Shimano 105 shifter and at the other end to the derailleur.
Cut the metal cap, called the "ferrule," away from the end of the cable, using cable cutters. Grab the cable where it enters the derailleur and pull it free.
Squeeze the shift lever on the Shimano 105 gear shifter to expose the head of the cable. The cable head is located on the side of the top of the shift lever.
Grab a portion of the cable and push it forward, forcing the head of the cable out of the Shimano 105 gear shifter. Grab the head of the cable and pull the cable free.
Shimano 105 Shifter Cable Installation
Thread the replacement shifter cable through the hole in the Shimano 105 gear shifter. This is the same hole from which the old cable emerged. The cable has two ends, with a metal fitting at one end, which is designed to anchor the cable inside the shifter.
Pull the shifter cable taught until the metal fitting is fully anchored.
Pass the cable along the bicycle. The cable follows the exact route of the old shifter cable, passing through the cable housing and cable stops before arriving at the derailleur.
Thread the shifter cable beneath the derailleur bolt and pull the cable tight.
Tighten the derailleur bolt onto the cable, using the 5-mm hex wrench. The cable will be excessively long and will need to be cut.
Cut the cable just past the derailleur bolt, using the cable cutters. Leave enough cable, approximately 2 to 3 inches, to allow for future adjustments of the cable.
Press a new ferrule onto the tip of the cable. Squeeze the ferrule onto the cable using pliers.