Learning to fit Shimano Sora shifters will not only save money but will provide a better understanding the gear and brake systems on racing bicycles. Sora shifters are Shimano's entry-level STI (Shimano Total Integration) shifters and are designed for use with other Shimano components. Check with a sales clerk at a bike store that Sora shifters are compatible with your existing gear and brake systems if you are unsure. Installing new Sora shifters requires no specialist tools or knowledge.
Remove Existing Shifters
Pull out the bar ends and unravel the handlebar tape on both sides of the handlebars, starting in the middle.
Cut the ferrules--the protective metal ends--off the ends of the two gear cables and two brake cables using cable cutters. Detach the gear and brake cables from the derailleurs and brake calipers by unscrewing the anchor bolts with an Allen key or an adjustable wrench as appropriate.
Pull the metal inner cables through the plastic-coated outer cables and out of the end of the old shifters. This may require you to squeeze the shifters as if you were braking to reveal the cable ends. If any of the cables appear to be rusty or frayed, purchase replacements.
Release the clamps that fasten the shifters to the handlebars, using an Allen key, and slide the old shifters off the ends of the handlebars. Slide the Shimano Sora shifters onto the handlebars and attach them by firmly tightening the clamp bolt--located under the rubber hood on the opposite side to the small shifting lever--using an Allen key.
Fit Gear Cable
Squeeze the brake levers to reveal a hole on the outside of each shifter. Thread the metal gear cable inners back through the shifters and through the plastic-coated gear cable outers.
Pull firmly on both gear cables in turn and click the small shifting lever on the inside of the mechanism until no more cable will pull through. Screw clockwise the cable tension adjustment barrels--located on either side of the frame downtube and on the rear derailleur--to further slacken the gear cables.
Pull on each gear cable in turn, and while maintaining tension, clamp the cable to the derailleur by screwing down the anchor bolt. Unscrew the adjustment barrels on either side of the frame until the front and rear derailleurs smoothly shift the chain up to the next cog.
Fit Brake Cable
Squeeze the levers forward and thread the brake cables through the top of the shifters. making sure the molded metal ends sit securely in the metal barrels visible inside the shifter. Thread each cable through the remaining plastic-coated brake cable outers.
Pull on each brake cable in turn, and while maintaining tension, clamp the cable to the brake caliper by screwing down the anchor bolt. Unscrew the adjustment barrels on top of each caliper until the brake pads are as close to the rim as they can get without touching.
Place new ferrules on the end of each cable (both gear and brake) and squeeze them firmly with pliers until they are secure. This will prevent the cable ends from fraying. Rewrap the handlebar tape and refit the bar ends. Use electrical tape to secure the ends of the tape to the handlebars.