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Discussion Starter · #1 ·
From what I have read my Ibis originally came with a 68x107mm long BB.

Now I want to put a set of Race Face Prodigy cranks on it, can I use that measurement (68x107mm) to get an ISIS BB for it? or is there a way to measure a frame to figure out what size I really need?

Thanks!
 

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Can you borrow a 107 and a 113 from somebody to use for measuring the chainline? It could be either. I happened to have one of each on hand for the two bike I have with ISIS RaceFace cranks. You just need to thread it in the drive side and install that crank arm so you can measure the chainline. Best place to start in my opinion. And if you are going to get the BB from your LBS they can maybe figure it out for you, if they happen to be a well stocked shop especially.
 

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Discussion Starter · #3 ·
IF52 said:
Can you borrow a 107 and a 113 from somebody to use for measuring the chainline?
what is the rule of thumb as far as measuring once I have one on there? is it the distance between the frame and the small chain ring?
 

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Discussion Starter · #5 ·
bushpig said:
MTBNJ - were you the guy racing the Mojo this weekend at the Bulldog Rump?
unfortunately no. Currently I'm riding a Tomac 98 special. My Mojo is being built. BUt when it's done, you'll see it. I heard the race was good.
 

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mtbnj said:
what is the rule of thumb as far as measuring once I have one on there? is it the distance between the frame and the small chain ring?
Chainline is measured from the centerline of the seat tube to the centerline of the middle ring. Better explanation is here:

http://www.sheldonbrown.com/chainline.html
 
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