Joined: Jan 2010
Posts: 9,835
Likes: 1,816
From: Northern California
Bikes: Cheltenham-Pedersen racer, Boulder F/S Paris-Roubaix, Varsity racer, '52 Christophe, '62 Continental, '92 Merckx, '75 Limongi, '76 Presto, '72 Gitane SC, '71 Schwinn SS, etc.
This is where having a mid-length cartridge bottom bracket handy is great for testing the fit and the chainline dimension.
Starting with say a Shimano 113mm cartridge and test-fitting to determine if the needed bb will have to be longer or shorter than that.
Even a worn-out cartridge bb is usually fine for such test-fit purposes, so I keep a few around, in lengths that I don't have new ones.
I have (for example) used a 115mm Shimano cartridge bb to mount Stronglight 93 cranks, with a resulting optimal chainline and good overall fit and function.
As Chas has often said on this forum, "if it fits, it works"!
And, since these mid-length and shorter Shimano Cartridge bb's are symmetrical, it is possible to use a fixed-cup spacer to add a little offset, if needed, for chainring clearance or for front derailer downshifting performance. But I always try for a minimum amount of Chainline offset as a starting point, the better to reduce friction as the chain crosses toward the smaller cogs.