Bottom Bracket Replacement Question
 

I have a 1988 Trek 660 with Shimano 600 Ultegra with a worn bottom bracket. The spindle size is 68 x 116 with 1.37 x 24 shell threading. I was thinking of using the Shimano BB-UN54 however the closet size is 68 x 115. What kind of problems (adjustments) will the 115 (vs. the existing 116) create?

115 to 116 is 1 mm ... 1mm divided in 2 is 0.5 mm do you think it will be a problem to have a 0.5 mm longer bb axle at each side?

If the original bb is symmetric just be sure the one is symmetric too. If asymmetric get asymmetric, besides that doubt you will have a single problem.

Good luck :D

Thanks. Going from a 116 to 115 would be 0.5 mm shorter per side not longer. I didn't think it would make a difference but I just want to make sure.