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.