The axle is the steel bolt that passes through the fork legs or swingarm and through the wheel bearings. Spacers (collars) on each side hold the wheel in the right position, and a nut, often with a split pin, holds it all together.
What it does
The axle holds the wheel in place and lets the bearings carry it. The spacers keep the disc centred in the caliper and the sprocket in line with the chain. A bent axle makes the wheel wobble and wears bearings; a missing spacer pulls the wheel out of line and can let the brake disc rub.
Signs it is worn or failing
- Wheel wobbles or rocks: Wheel moves sideways on the axle, Wheel is buckled or wobbles.
- Bike pulls or chain runs out of line: Bike pulls to one side.
- Brake drags after refitting a wheel: Brake drag.
- Axle hard to remove, rusty or with damaged thread.
When to replace it
Replace an axle that is bent beyond the limit, has a damaged thread or deep rust where the bearings sit. Never straighten an axle. Replace self-locking nuts and split pins each time.
What to match when buying
- Make, model, year, front or rear. Diameter, length and thread (for example M14×1.5).
- Spacers must match length and inner and outer diameter exactly; take the old ones to the shop.
- Buy a new nut and split pin with it.
Fitting notes
- Note or photograph spacer positions before removal.
- Roll the axle on a flat surface or check on V-blocks with a dial gauge to find a bend.
- Tighten the axle nut to the value for your bike and that exact nut. For the K-Light 125 rear axle the manual gives two values; confirm before work.
- See Remove and refit the front wheel and Remove and refit the rear wheel.
Reference (K-Light 125)
| Item | Value | PDF page |
|---|---|---|
| Front axle nut | M14×1.5, 75 to 88 N·m | 130 |
| Rear axle nut | M16×1.5 | 158 |
| Axle bend limit, front and rear | 0.2 mm | 130, 164 |