Why does my rear mech derailleur hanger keep breaking?

A rear mech derailleur hanger is a small component on a bicycle frame that serves as a connection point between the rear derailleur and the frame. Its purpose is to protect the frame from damage in case of an accident or mishap by breaking or bending. If your derailleur hanger keeps breaking, there are several potential reasons for this recurring issue:

1. Impact or Crash Damage: If you’ve had an accident or impact on the rear derailleur, the hanger might have incurred damage.

2. Shifting Issues: Sometimes, excessive force on the gears, such as changing gear under high load, or a problem where the chain gets stuck due to debris or a other damaged drivetrain components, can put extra strain on the derailleur hanger, causing it to break prematurely.

3. Bent or Misaligned Hanger: Even a slight bend or misalignment in the derailleur hanger can cause shifting issues and increase stress on the hanger. A bent hanger will not only impact shifting performance but can also weaken the part, leading to breakage.

The good news is that derailleur mech hangers are easy and inexpensive to replace, but to ensure you are not repeatedly breaking your hanger, you can take the following steps:

  • Clean your bike drivetrain regularly
  • Check the hanger regularly too – don’t try to bend back a replaceable hanger, just replace it.
  • Check other components, and replace any damaged ones, the most likely are: bent derailleur cages and best cassette teeth.
  • Change your shifting technique – you’ll hear crunching sounds if you change gears while pedaling hard which isn’t great for your chain or cassette but can also impact on the longevity of your hanger