Replacing a Freehub Body on a Rear Bicycle Wheel.

Picture of Replacing a Freehub Body on a Rear Bicycle Wheel.
I am learning more about bicycle maintenance by practicing on my own bike. 

Last night my bike broke, I was pedaling, but the bike wasn't moving!

We soon realized that the ratchet mechanism in the rear wheel was broken.


Time to learn how to replace a freehub body!

You will need:
  • cassette spline tool
  • suitable spanner for cassette spline tool
  • chain whip (or vise whip)
  • cone spanner (usually 15mm, 2 spanners make it easier.)
  • spanner (usually 17mm, 2 spanners make it easier.)
  • large Allen key to fit freehub (usually 10mm, sometimes 12mm or 14mm.)
  • bicycle grease
  • replacement freehub body
You can buy all of these tools, or if you are lucky you might have a local d.i.y. bike workshop who will lend you tools.

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Step 1: Diagnose the problem!

Picture of Diagnose the problem!
If you can spin the pedals, but the back wheel isn't moving, and the chain is all on correctly, then this means that the ratchet mechanism that allows you to freewheel is probably broken.

The action of freewheeling is when your bike is moving along but you don't have to spin the pedals.

There are two very different types of ratchet mechanisms on a bicycle.

There is a thread-on freewheel where the ratchet mechanism is within the sprockets.

There is also the more modern freehub and cassette where the ratchet mechanism is within the freehub body.

On my bike I have a freehub so I need to replace it to fix the problem. If you have a thread-on freewheel you just need to replace the freewheel unit.

(Second photograph stolen from - excellent resource for bike mechanics.)
rimar200011 months ago

Thanks for sharing, this is very useful.

Snotflower (author)  rimar200011 months ago

gracias por los comentarios, que me alegro es útil!