I was putting on a new bottom bracket onto my PC3 last night. I'm taking out a FSA Mexa Exo and putting in an ultegra 6800. The cranks came out easily from the bottom bracket. After screwing in the 6800, the cranks did not want to go back in. On the shaft there's a small rise at both ends, right next to the grooves for the crank arms. It barely didn't want to go through. With some tapping from the hammer it went through and is spinning fine by hand. Is that normal? Will it wear in? I've only changed 2 bottom brackets before and didn't have this issue either time. Any ideas or feedback?
Triathlon Forum
Login required to started new threads
Login required to post replies
Re: New Bottom Bracket Fit [mkng1]
[ In reply to ]
I think the ID of a Shimano BB is fractionally smaller than an FSA one. Shimano is 24mm and FSA is 24 and "a bit"
I fitted a new Shimano BB for a friend in lieu of an FSA one (FSA crank) and had to knock it through. The BB bedded in ok. In fairness she was just setting off to do a 1000 mile ride ( over a week) and never complained.
I'm reasonably sure that's right :-)
LG
I fitted a new Shimano BB for a friend in lieu of an FSA one (FSA crank) and had to knock it through. The BB bedded in ok. In fairness she was just setting off to do a 1000 mile ride ( over a week) and never complained.
I'm reasonably sure that's right :-)
LG
Re: New Bottom Bracket Fit [lagazelle]
[ In reply to ]
That's an accurate description of my experience in terms of sizes. The change was in advance of IMTX next week so hopefully a couple practice rides will validate it's still all good.
Re: New Bottom Bracket Fit [mkng1]
[ In reply to ]
mkng1 wrote:
I was putting on a new bottom bracket onto my PC3 last night. I'm taking out a FSA Mexa Exo and putting in an ultegra 6800. The cranks came out easily from the bottom bracket. After screwing in the 6800, the cranks did not want to go back in. On the shaft there's a small rise at both ends, right next to the grooves for the crank arms. It barely didn't want to go through. With some tapping from the hammer it went through and is spinning fine by hand. Is that normal? Will it wear in? I've only changed 2 bottom brackets before and didn't have this issue either time. Any ideas or feedback?I'm not an expert, but I also have a FSA MegaExo and have recently watched a LOT of bike videos so I could learn about servicing my BB. (I have a old Dura-Ace crank.)
One of the videos showed exactly what you experienced - BB came out easily, but the guy had to tap in the Shimano crank with a rubber hammer.
Re: New Bottom Bracket Fit [lightheir]
[ In reply to ]
Awesome. Even more comforting. I changed out an Ultegra crankset on my road bike (2006 Trek) and had no such issues so it was disconcerting but glad to know not unique.
Perfectly normal.