Frame, Chassis, and Bodywork Inspection
This domain covers structural inspection, damage assessment and correct refastening after repair.
Core rules
- Check frame alignment at the steering head and swingarm pivot; a bent frame on a road bike is replaced, not straightened.
- Inspect welds and gussets for cracks, especially around engine mounts, headstock and shock mounts; dye penetrant helps on castings.
- Fork tubes: any bend beyond a small runout tolerance means replacement - straightened tubes crack and seize.
- Fasteners: use the specified torque, thread pitch and grade; 8.8 and 10.9 bolts are not interchangeable. Apply thread locker where specified, anti-seize on dissimilar metals, and never lubricate a fastener whose torque figure is specified dry.
- Bodywork: check clips and rubber grommets for cracks and missing parts - a loose panel can mask vibration and foul the steering or rear wheel.
- After any repair, verify steering lock-to-lock clearance, cable routing, and that nothing touches tyre or chain.
Worked example
A bike arrives after a low-speed slide with the bars slightly off-centre when riding straight. Reasoning: the bars may be twisted in the clamps, the fork tubes bent, or the frame bent. Loosen the triple clamps and check tube runout first; if the tubes are straight, check steering stops and the headstock for cracking. Only when the front end is confirmed true do you evaluate the frame - this order avoids replacing a frame for a bent tube.
Traps that cost marks
- Straightening fork tubes.
- Reusing damaged or torque-to-yield fasteners.
- Forgetting ground straps and harness clips when refitting bodywork.