Replace a shifter cable

A frayed or sticky shifter cable makes gears slow, skip or stop shifting. Replacing the inner cable on a flat bar trigger shifter is a good first cable job. This guide follows Park Tool's trigger shifter cable guide and its housing guide. Electronic shifting is different and is not covered here.

What you need

• A new shifter cable, and new housing if the old housing is kinked or worn
• Cable cutters. Park Tool uses its CN-10 (Park Tool).
• Hex keys and a torque wrench
• A small flat screwdriver, a pick and a flashlight
• A cable end cap and a crimping tool, plus a light lube (Park Tool)
• A bike repair stand helps

Steps

1. Turn the bike off and remove the battery.
2. Shift to the smallest rear cog. Park Tool has you work the release lever while turning the pedals to let out as much cable as possible (Park Tool).
3. Loosen the anchor bolt on the derailleur. If the cable end is frayed or kinked, cut it off so the cable slides out easily (Park Tool).
4. Find the cable head in the shifter. Pull the housing back from the shifter. On some Shimano shifters a plastic plug unscrews, and on others a top cover lifts off. On SRAM, there's an access hole or rubber cover, or the top cover has to come off (Park Tool).
5. Push the old cable out through the shifter and pull it free. Note how it was routed.
6. Check the housing. Park Tool says to replace housing that's kinked, worn, frayed or corroded, or when shifting is slow or hard (Park Tool). Cut new housing with a proper cutter, open the liner with a pick, and fit a ferrule on both ends unless a part is sized for bare housing (Park Tool).
7. Feed in the new cable. Thread it through the shifter until the head seats with a firm pull, then route it through each housing section to the derailleur. Replace the shifter cover or plug (Park Tool).
8. Clamp the cable. Lay it in the groove at the derailleur anchor, pull out the slack and tighten the pinch bolt. Park Tool gives about 5 Nm as typical (Park Tool). Rad lists 6 Nm for the shift cable clamp on the RadWagon 5 (Rad RadWagon 5 manual). Use your derailleur's spec.
9. Trim and cap. Cut the cable to about 30 mm past the bolt and crimp on an end cap (Park Tool). Park Tool says the cap keeps the strands bundled (Park Tool).
10. Index the gears. Set the limits and indexing as in adjust the rear derailleur.
11. Put the battery back and test ride, shifting through every gear. New cables can stretch a little, so recheck the indexing after a few rides.

Common mistakes

• Starting in a big cog, so the cable is clamped with the wrong tension.
• Leaving out ferrules, which lets housing ends collapse.
• Housing that's too short and kinks when the bars turn. Park Tool says to keep housing as short as practical but long enough to feed straight into the stops and allow the bars to turn (Park Tool).
• Tightening the zip ties before the routing is set. Park Tool leaves them loose until then (Park Tool). See zip ties.
• Letting a cable or zip tie squeeze a motor, sensor or brake cutoff wire.

Videos

When to get a pro

• Internal frame routing, where the cable runs inside the frame beside e-bike wiring.
• Twist shifters, internal gear hubs and electronic shifting.
• Shifting that still won't index after a new cable. The derailleur hanger may be bent. See derailleur hanger.

Sources

• Shift Cable Replacement: Trigger Shifters, Park Tool
• How to Size and Install Shift Cable Housing, Park Tool
• RadWagon 5 owner's manual, Rad Power Bikes

Stuck after these checks? Find a shop near you.