As I learned in this question, the cog of my freewheel are damaged and should be replaced.

I've been searching for some information but I'm still not sure of what I need. At the beginning I though I just needed to search for a cog like this with 1/8" like my chain: cog

But reading the description it seems like it's only for fixed gears, so I was completely worng. Searching for more items under the single speed category in the website everything looked like that.

What do I need to buy as replacement?

This is how what I have now: my cog

As tools a I just have the basics, when i search for freewheel remover I see hundreds of different things like this: tool1 tool2 tool3 ...

How can I know what I need?

Update with photo of the wheel: freewheel

  • You have a flip flop hub. If the fixed side is not worn, then consider flipping it and riding on the fixed side, to see if the noises reduce or go away.
    – Criggie
    Commented Apr 30, 2018 at 7:18

1 Answer 1


Park tool has a guide to figuring out what type of free hub/freewheel you have, and what tool you need to get it off.


With that knowledge you should be able to to figure out what type of replacement freewheel/spocket you need (or two, as you have a flip-flop hub).


Also see the Sheldon Brown page on Freewheels.

Depending on what the freewheel thread turns out to be, you should be able to get a replacement freewheel that has a more standard lockring.

You might consider creating a 'bodged' tool to get the current freewheel off. You might be able to 'drift' the lockring loose by tapping the ring around with an old screwdriver and hammer.

  • Thanks, it looks like I need a freewheel + it's extractor, but I can't find any extractor with 8 notches as my current freewheel has.
    – nck
    Commented May 1, 2018 at 11:12
  • Did the Park Tool guide not help? Can you provide a well lit photo of the FW with the wheel out of the bike? It's a bit hard to see the lock-ring in the pic you provided. Commented May 1, 2018 at 11:31
  • sorry I didn't had time to extract the wheel. I just uploaded a new photo. I can't see any parktool tool with those 8 notches nor find something similar in the amazon from my country.
    – nck
    Commented May 2, 2018 at 17:40
  • 1
    I have a similar looking 8-notch freewheel. It is compatible with 4-notch tool, leaving other 4 unused.
    – ojs
    Commented May 2, 2018 at 19:12
  • 2
    Park FR-3, -4 and -8 are 24, 40 and 32mm in diameter respectively. You'll need the one which is closest the diameter of your lockring. Commented May 2, 2018 at 21:03

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