What are Frame / Chassis?
The structural skeleton that holds the engine, suspension and rider in correct relation to each other.
Simplified animation — not to scale.
In plain English
Every other part of the bike bolts to the frame, which has to hold the engine, suspension, steering and rider in precise alignment while absorbing the forces from acceleration, braking and cornering.
“The bike's skeleton — everything else is muscle, organs or skin hung off this central structure.”
How it works
Built from steel or aluminium tube, pressings or castings, the frame ties the steering head at the front to the swingarm pivot and engine mounts, keeping their relative geometry fixed under load. That geometry — steering angle, wheelbase, weight distribution — is what defines how a bike actually handles.
Signs of trouble
- ⚠Visible cracking, especially near welds or mounting points
- ⚠Corrosion on a steel frame, particularly underneath
- ⚠Bike feeling vague or unstable that isn't explained by tyres or suspension
- ⚠Misaligned wheels after an impact
£200–£2,000
Always get a written quote. Prices vary by bike, region, and parts brand.