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Discussion Starter · #1 ·
Greetings, I think I've asked before, but now that I'm actually working on it I need help understanding. I have a SISL crank and ring off a FAT CAAD. I'm wanting to use it on a Surly Wednesday (don't ask...) So I mocked up the bb/crank to see where the OPI 30T Fat ring would land, and it is at the 71mm chainline give or take. I need to bring that in a good amount if I can, so I think I need a new ring with different offset.
According to this image
1942659


The FAT CAAD has a 9mm offset.
1) how is that number measured?
2) I'm pretty sure I can flip this ring, is there any harm/danger in doing so?
3) are the Standard rings flat/flush with 0mm offset?

Thanks in advance.

I suppose option 4) should I just get a 64/104 (or other 4-/5-bolt) spider and use easier to source chainrings?
 

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I'm not sure what you're trying to do, but the Fat Caad chainring in an oddball. Here are some docs to peruse:

A sketch I made for an mtbr'er of measurements off of my Fat Caad with a Wolftooth Camo set-up.


Hollowgram line-up showing spindles and spiders:


Wolftooth website that does a good job showing the various Cannondale offsets & chainlines:

 

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Discussion Starter · #4 ·
Thanks for the links @J_Westy, I'll definitely have to look those over more. I'm definitely working with an oddball setup, since its a 100mm BSA threaded shell. I'm not sure if I can step down to a 149.5mm cinch spindle (I'm using raceface spindles), I'll have to measure the clearances I have between the arms and the chainstays to be sure. I could have gained another mm or 3 by fully tightening everything down; I went "snug" on the setup just to start eyeballing and seeing how things would end up. I do have room to flip the chainring inward towards the frame amazingly enough and it looked like it would be sitting in an ok spot, but I'll want to tighten everything up real good to make sure that doesn't hit the frame.
To be safe/experiment more, I did order an Absolute Black with the 4mm offset and I'll have that as backup.
 

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Thanks for the links @J_Westy, I'll definitely have to look those over more. I'm definitely working with an oddball setup, since its a 100mm BSA threaded shell. I'm not sure if I can step down to a 149.5mm cinch spindle (I'm using raceface spindles), I'll have to measure the clearances I have between the arms and the chainstays to be sure. I could have gained another mm or 3 by fully tightening everything down; I went "snug" on the setup just to start eyeballing and seeing how things would end up. I do have room to flip the chainring inward towards the frame amazingly enough and it looked like it would be sitting in an ok spot, but I'll want to tighten everything up real good to make sure that doesn't hit the frame.
To be safe/experiment more, I did order an Absolute Black with the 4mm offset and I'll have that as backup.
I hope it worked out.
 
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