Shimano Chainline

J

Joe_MTB

Likes Dirt
I've just installed a shimano M9000 1x crankset onto my frame (no chain as yet) along with a hope chain device. I've found that even with all of the supplied spacers onto the ISCG tabs, the chainring is still sitting towards the outside of the chain device and will probably rub when I install the chain.

Is this normal for shimano chain rings to sit so far out? I've only over used race face before now. I've installed the BB with a spacer on the drive side as per instructions but could swap this to the other side, but not sure if this would be a good idea. *Edit* looks like if I swapped the spacer the crank would come close to hitting my chain stay
 
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C

ChrisJC

Likes Bikes and Dirt
Joe_MTB said:
I've just installed a shimano M9000 1x crankset onto my frame (no chain as yet) along with a hope chain device. I've found that even with all of the supplied spacers onto the ISCG tabs, the chainring is still sitting towards the outside of the chain device and will probably rub when I install the chain.

Is this normal for shimano chain rings to sit so far out? I've only over used race face before now. I've installed the BB with a spacer on the drive side as per instructions but could swap this to the other side, but not sure if this would be a good idea. *Edit* looks like if I swapped the spacer the crank would come close to hitting my chain stay
Click to expand...
What is the current chainline and BB shell width? If it's 73mm you shouldn't need BB spacers.
 
J

Joe_MTB

Likes Dirt
It is a 73mm but the hope install instructions show it needing a spacer on the drive side?
 
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The Duckmeister

The Duckmeister

Has a juicy midrange
ChrisJC said:
What is the current chainline and BB shell width? If it's 73mm you shouldn't need BB spacers.
Click to expand...
External bearing bottom brackets and cranks are designed to allow for the fitting of a BB-mounted chain device, so if one is not used (eg, ISCG tabs instead), a spacer is fitted in its place, even on a 73mm shell (a 68mm shell therefore would have two on the drive side and one on the off side, to allow for both the shell difference and the absence of BB-mounted chain device).
 
C

ChrisJC

Likes Bikes and Dirt
Joe_MTB said:
It is a 73mm but the hope install instructions show it needing a spacer on the drive side?
Click to expand...
with the spacer installed, what is your chainline measurement? Should be around 50mm or a touch more if it's a shimano 1x chainring.
 
J

Joe_MTB

Likes Dirt
ChrisJC said:
with the spacer installed, what is your chainline measurement? Should be around 50mm or a touch more if it's a shimano 1x chainring.
Click to expand...

Bang on 51mm. Maybe it's just that the ISCG tabs are further inboard than other frames. Guess I'll just have to buy some more washers...
 
moorey

moorey

call me Mia
Joe_MTB said:
Bang on 51mm. Maybe it's just that the ISCG tabs are further inboard than other frames. Guess I'll just have to buy some more washers...
Click to expand...
Lbs will have a box of spares surely? I keep old ones, and often have spare new ones.
 
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