On many older and budget bikes, a speedometer cable runs from a small gearbox on the front wheel hub to the back of the speedometer. Many newer bikes use an electronic Speed sensor and a wire instead.
What it does
A drive gear in the wheel hub turns an inner cable, which spins a magnet in the speedometer. The faster it spins, the higher the needle reads, and it also turns the odometer. The inner cable wears, dries out and breaks, especially if the cable is bent tightly. The hub drive housing must be fitted with its tangs in the hub slots, or the gear is crushed.
Signs it is worn or failing
- Needle does not move: Speedometer cable is noisy or broken, Speedometer does not work.
- Needle swings or flickers, or the cable squeals.
- Front wheel hard to turn: the drive housing may be damaged.
When to replace it
Replace the cable if the inner is broken, kinked or rusted, or the outer is cracked. If a new cable does not fix it, check the hub drive gear and the speedometer head.
What to match when buying
- Make, model and year. Length, end type (screw nut or clip) at both ends and the square or slotted inner tip.
- Disc and drum brake versions of one model can use different cables and drive housings.
- Electronic speedometers do not use a cable; buy the sensor instead.
Fitting notes
- Route with gentle curves; tight bends break the inner cable.
- When refitting the front wheel, make sure the drive housing tangs engage the hub and spin the wheel to check the needle moves.
- See Replace the speedometer cable and Remove and refit the front wheel.