Among Shimano's multiple groups of road bike components, Dura Ace represents the company's premium offering. The Dura Ace 10-speed rear shifter uses a cable connected to a mechanism known as a derailleur in order to actuate gear changes. The derailleur is located at the end of the cable opposite the shifter. When shifter cables stretch too much, they no longer offer the tension needed to pivot the derailleur to certain gears. A new cable, adjusted properly, allows the shifter, cable, and derailleur to work effectively.
Use the rear Shimano Dura Ace shift lever to shift into the largest gear. The chain should now be positioned on the outer rear sprocket.
Use cable cutters to remove the shifter cable end cap. The end cap is attached to the very end of the shifter cable, just past the derailleur.
Loosen the shifter cable anchor bolt beneath the Dura Ace derailleur, using a 5mm hex key.
Pull the rear shift lever into the handlebar to expose the head of the cable inside the shifter.
Force the cable up and out of the cable hole in the shifter. Pull the cable away from the shifter, and discard.
Insert the new cable through the same hole from which old cable emerged. Continue to feed the cable into the Shimano Dura Ace shifter.
Guide the cable to the rear derailleur, following the exact path as the old cable.
Fit the end of the cable through the plastic housing at the rear of the derailleur, and feed it through.
Pass the cable between the anchor bolt and the derailleur. Pull the end of the cable, and tighten the anchor bolt onto the cable.
Note the excess of cable beyond the anchor bolt. Use cable cutters to cut the excess cable, leaving just two inches of cable remaining past the anchor bolt.
Press a shifter cable end cap onto the freshly cut cable. Squeeze the sides of the end cap with pliers to mash the cap in place.
Twist the shifter cable adjustment barrel in toward the bike to increase tension on the cable. The adjustment barrel is found where the cable meets the derailleur. Adding tension to the cable allows the derailleur to pivot to other gears. To test the adjustment, take the bicycle for a short ride and try shifting. If some gears are inaccessible, use the adjustment barrel to add more cable tension. Test the gears following each turn of the barrel to prevent over-adjustment.