OD of 40 and 42 tooth cinch chainring?- Mtbr.com

# Thread: OD of 40 and 42 tooth cinch chainring?

1. ## OD of 40 and 42 tooth cinch chainring?

I am looking to fit a 40 or 42 tooth chainring to a fat bike in a sort of Monster-cross fatty build. looking to get more of a road suitable gearing option. I am currently running a Turbine cinch crank with 32T and it has lots of room to spare before contacting the chain stay. I am trying to get the biggest chainring possible with out buying a few and having to sell the ones i don't need. So if anyone could measure the OD of their 40T or 42T chainring that would be awesome.

2. Originally Posted by Jefflinde
I am looking to fit a 40 or 42 tooth chainring to a fat bike in a sort of Monster-cross fatty build. looking to get more of a road suitable gearing option. I am currently running a Turbine cinch crank with 32T and it has lots of room to spare before contacting the chain stay. I am trying to get the biggest chainring possible with out buying a few and having to sell the ones i don't need. So if anyone could measure the OD of their 40T or 42T chainring that would be awesome.

40t sram is 6-5/8"
42t absolute black 6-7/8"

3. Perfect. Thank you so much

4. if you have a Cassette cluster with a 42 tooth cog on it
you can always measure that.

a 42tooth cog is just about the same size as a 42tooth chainring.

5. Pretty simple math if you're into that. Teeth are spaced at half inch intervals to line up with our links. So a 40t ring had a circumference of 20". C = Pi x D or 6.37" in diameter.

6. The biggest cog i have is a 38 and i figured there was a math trick but didn't know what it was. thanks again everyone for your help.

7. Originally Posted by Shinkers
Pretty simple math if you're into that. Teeth are spaced at half inch intervals to line up with our links. So a 40t ring had a circumference of 20". C = Pi x D or 6.37" in diameter.
Except the measured diameter above is 6.625". I suspect because the teeth stick out farther than the midline of the chain.

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