SF Cyclotouring

Ride reports and other ramblings from a San Francisco cyclist.


Shimano Square-Taper BB Sizing

Posting this here as a bookmark of sorts...helpful info on selecting the right Shimano square-taper cartridge BB for your application.

From this iBOB post:

107, 113, and 118 are asymmetric. 110 & 115 are symmetrical. The increase in axle length is what you two described earlier; i.e., drive side of 110 = drive side of 107 and so on.

And from another iBOB post:

The steps are such that you can get any chainline in 1mm steps over a 12mm range without using more than the "Shimano approved" 2mm spacer under the fixed cup. In some cases, you get to choose lower Q or left-right symmetry. I'm also pretty sure that all levels of Shimano cartridge follow the same pattern. He used a cheat sheet like this that I copied (but it wouldn't hurt to double check for yourself; I haven't tried all the combinations):

chainline spindle_length right_side_spacer
+ 0 107/110.5
+ 1 107/110.5 1mm
+ 2 107/110.5 2mm
+ 3 113/115
+ 4 113/115 1mm
+ 5 118
+ 6 118 1mm
+ 7 118 2mm
+ 8 122.5
+ 9 122.5 1mm
+10 122.5 2mm
+11 127.5

See this thread for more details.


Anonymous Anonymous said...

solid ibob gold, that one.

9:00 PM  
Blogger Jeremy said...

Not sure if this is referenced in the iBob thread but Harris Cyclery posted a table showing the drive-side spindle lengths (and hence relative chainline) of all the shimano UN54 sizes on their blog:


Has definitely been helpful.

7:55 AM  

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