I plan to mount a Sugino XD300 on an vintage Trek steel frame (1 1/8" seat tube, 126 OLD rear spacing, Suntour Ultra 6 speed freewheel). In order to achieve the best chainline, can anyone recommend the appropriate BB spindle size? I plan to use a Shimano UN53 sealed unit. Most retail websites recommend 113mm and 118mm for the XD cranks. My guess is that because of the narrow tubes of the Trek (alignment of FD) and narrow OLD (chainstays not as flaired?), 113 would be appropriate. Or should I go with something even shorter?
I realize there are lots of variables involved here. Just wondering if anyone is running a similar setup on a vintage frame.