Repair guides › Cockpit
Install a new fork (cut the steerer)
The bearings that let the fork turn in the head tube. Two bearings (top and bottom) sit in cups pressed into the head tube. The stem clamps the steerer; the top cap bolt pulls the fork up to take out play (preload), then the stem bolts lock everything. Budget bikes often use caged ball bearings (EC sizing).
Open this job in RideLoadout▶ Watch it done
Tools
- Ball-end hex key set (1.5–10 mm): Park Tool HXS-1.2 Professional L-Shaped Hex Set ($$)
- 1/4" click torque wrench (about 2–17 Nm) + bits: Pro Bike Tool 1/4 inch drive click torque wrench set (2.2–16.9 Nm) ($$)
- Tape measure + 6" steel ruler: Stanley 16 ft tape measure ($)
- Bike grease: Park Tool PPL-1 PolyLube 1000 ($)
- Carbon assembly paste: Park Tool SAC-2 SuperGrip Carbon and Alloy Compound ($)
- Repair stand: Park Tool PCS-9.3 Home Mechanic Repair Stand ($$$$)
- Soft mallet + star-nut setter: Rubber mallet + star nut setting tool ($$)
- Crown race setter: Foundation crown race setting tool ($$)
- Saw guide + hacksaw (steerers, bars, posts): Park Tool SG-7.2 saw guide and a hacksaw ($$$)
Compare Good, Better and Best for each tool
Steps
- Check the new fork matches the bike: steerer size and taper, axle standard, brake mount, wheel size and axle-to-crown length.
- Seat the crown race fully on the new fork crown with the crown race setter (no gap).
- Fit the fork through the head tube with the headset, spacers and stem where you want them, and mark the steerer at the top of the stem.
- Take the fork out. The steerer must end about 3 mm below the top of the stem (or top spacer). Measure twice, then cut slowly and square in the saw guide with a 32 TPI blade. Carbon steerers: a fine carbon blade, a dust mask, and never a pipe cutter. You can't add length back.
- File the cut edge smooth. Alloy or steel steerer: drive a star nut in about 15 mm below the top with the star-nut setter. Carbon steerer: use an expansion plug, never a star nut.
- Reassemble, set preload with the top cap, align the stem and torque its bolts. Refit the brake and wheel, and test the front brake and steering before riding.
Torque
| Fastener | Torque |
|---|---|
| Stem steerer bolts | 5–6 Nm (check stem marking) |
| Carbon steerer | usually 5 Nm max, with carbon assembly paste |
| Caliper mount bolts | 6–8 Nm (Shimano/Tektro) · SRAM/Avid 9.5 Nm · check the caliper |
Diagram
Taken apart, in order, side viewHead tube and stem
Signs it needs doing
- Clunk felt through the bars when you hold the front brake and rock the bike
- Steering feels notchy or stuck straight ahead (worn bearings)
- Bars feel tight when turning (too much preload)