Gears & Shifting
What is a Derailleur Hanger?
A small, deliberately weak bracket that the rear derailleur bolts onto.
Simplified schematic — not to scale.
In plain English
The hanger is a small, replaceable piece of metal between the frame and the rear derailleur — designed to bend or snap in a crash so the frame itself doesn't.
A simple analogy
“It's the electrical fuse of the drivetrain: a cheap part that's meant to fail first, to save something far more expensive.”
How it works
The derailleur bolts to this bracket rather than directly to the frame. In an impact, the softer hanger bends or breaks, protecting the derailleur and frame from more serious damage.
Signs of trouble
- ⚠Gears suddenly shift badly after a knock or fall
- ⚠Derailleur hanging at a visibly crooked angle
- ⚠Chain jamming into the spokes
Rough UK cost
£8 – £25
Always get a written quote. Prices vary by bike, region and parts brand.
Heads up: Bikeautonomy is for general guidance only. If your bike is behaving oddly or you're not confident, get it looked at by a qualified bike mechanic.