I recently bought a second hand titanium frame set. The previous owner told me he had a Ultegra groupset on it. I had a bike with an older Ultegra 6800 group lying around so I thought I would just switch everything over. Everything seemed to fit nicely. But when I got to the crank things went sour. The axle went in but it would not turn freely at all. So I thought the BB was old so I decided to replace it. So I replaced the BB72 41 with a new BB72 41B. But when I had installed it the same thing happened. The first part goes in fine and turns free, but when I put it in all the way. It requires a lot of force and no longer turns freely. I’ve measured the axle and it reads 24 mm. I’m probably overlooking something simple. What am I doing wrong?
by Certain_Ad8242
3 Comments
You’ve probably overdone the preload, plus new bb’s don’t spin freely.
To reliably get good preload, do the cap up quite tightly, then back it right off and do it up very very lightly and set the pinch bolts to 12Nm or whatever the sticker says nowadays. The first tighten sets the crank on the axle correctly, the second means you can actually feel your pre-load.
Or just do what everyone does, do it up once tightish, and then let the break in sort the bb stiffness
Im Sorry for you but i trink you dont do anything wrong. Had my hands on 3 of those and all had problems with the tolerances at the bb or headset. Same problems like you have. For one customer I got an out of tollerance headset and it worked.
aside from other suggestions, check to see that the “cable housing guide” bolt (theunderside of the exterior of the BB shell) isnt rubbing against the BB inside of the shell.