A group of Shimano bicycle components, Acera is designed to provide the feel of performance-oriented parts to casual and entry-level cyclists. The Acera Rapidfire Plus shifter handles gear-shifting duties. The shifter is fitted with a cable, which is connected at the far end to a derailleur, the mechanism that transfers the chain to each sprocket. The cable is replaced as part of a yearly tune-up, or if the cable is damaged in any way.
Operate the Shimano Acera shifter lever until its cable has maximum slack. Turning the shift lever in one direction shortens the cable. Turning the shift lever in the other direction lengthens the cable. The cable can be seen and felt going slack.
Trace the cable from the Shimano Acera shifter to the derailleur. Use a 5mm Allen wrench to loosen the bolt that binds the cable to the derailleur.
Cut the metal cap off the end of the cable, using cable cutters.
Grab the cable and pull it free of the derailleur.
Follow the cable to the end opposite the derailleur, where the cable enters the Shimano Acera shifter. On the shifter and directly opposite, where the cable enters the shifter, there is an "inner hole cover."
Loosen and remove the inner cover, using a Phillips screwdriver.
Grab the cable and push it up so that the head emerges from the inner hole. Pull the cable from the Acera shifter.
Insert the bare end of the replacement cable through the inner hole in the Shimano Acera shifter. One end of the cable contains a metal fitting. The other end does not. This is the "bare" end.
Grab the cable as it emerges from the other end of the shifter, and pull the cable until the end with the metal fitting seats inside the Acera shifter.
Pass the bare end of the replacement cable through the derailleur and beneath the bolt that binds the cable to the derailleur.
Pull the bare end of the cable so that the cable is tight. Use the 5mm Allen wrench to tighten the bolt onto the cable. Release the end of the cable.
Cut the end of the cable with a cable cutter, leaving two to three inches of cable remaining from the bolt.
Press a shifter cable end cap onto the end of the cable, where the cable has just been cut. Squeeze the sides of the end cap with needle nose pliers, mashing the cap onto the cable.
Thread the inner hole cover back into the inner hole on the Shimano Acera shifter. Use the Philips screwdriver to turn the cover clockwise until the cover is tight. To prevent damaging the screw, do not tighten any further.