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-   -   Crankset Chainline (https://www.bikeforums.net/singlespeed-fixed-gear/1214318-crankset-chainline.html)

AMoney 10-01-20 08:58 AM

Crankset Chainline
 
I have an All City Nature Boy from 2015. The crankset is FSA Vero. The chainring is on the inner side of the spider. It came with a bash guard on the outer side of the spider but I since removed it. I think the chainline is 44 mm.

I am considering replacing the crankset (which has 130 bcd) with one with a 110 bcd. The reason I'm thinking about doing it now is because I will likely need to replace the chainring soon anyways. Can I mount the chainring on the inside spider of any singlespeed crankarm? If so, should I try to find one with a 110 bcd? Also, is the chainline for single and double cranksets different even if the chainring is mounted on the inner side of the spider?

Thanks

Rolla 10-01-20 10:19 AM


Originally Posted by AMoney (Post 21722513)
I think the chainline is 44 mm.

I believe it's 45mm, but find this out first.


Originally Posted by AMoney (Post 21722513)
I am considering replacing the crankset (which has 130 bcd) with one with a 110 bcd. The reason I'm thinking about doing it now is because I will likely need to replace the chainring soon anyways.

Why are you replacing the crankset if only the chainring is worn?


Originally Posted by AMoney (Post 21722513)
Can I mount the chainring on the inside spider of any singlespeed crankarm?

Not necessarily.


Originally Posted by AMoney (Post 21722513)
If so, should I try to find one with a 110 bcd?

I'm unclear on why you want to change BCD from 130 to 110.


Originally Posted by AMoney (Post 21722513)
Also, is the chainline for single and double cranksets different even if the chainring is mounted on the inner side of the spider?

Yes.

These may be helpful:
https://www.parktool.com/blog/repair...nline-concepts
https://www.sheldonbrown.com/chainline.html

AMoney 10-01-20 10:49 AM


I'm unclear on why you want to change BCD from 130 to 110.
I'm considering replacing the crankset because with a 130 BCD the smallest chainring I can use is 38 teeth. With a 110 bcd I could use a 34 tooth. I'm not sure I will actually change the crankset though.

Rolla 10-03-20 10:25 AM


Originally Posted by AMoney (Post 21722696)
I'm considering replacing the crankset because with a 130 BCD the smallest chainring I can use is 38 teeth. With a 110 bcd I could use a 34 tooth. I'm not sure I will actually change the crankset though.

If it was me, I'd avoid the whole chainline issue entirely and just replace the worn chainring with another 38T and replace the rear FW cog with a bigger one. If you go from a 38 to a 34T in front, you'll probably want a different FW cog anyway; that's a big decrease in gear inches.

AMoney 10-04-20 07:15 AM

Thanks for the advice. I decided to keep the crankset and just replace the chainring. If I want an easier gear ratio I will just get a bigger freewheel but I probably won't do this in the near future. With a singlespeed I'm always in the wrong gear anyways. ;-)


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