With the help of a semi-experienced mechanic buddy, I just installed a new Dura Ace bottom bracket. Does it have a break in period before it spins freely? Should it spin freely? (When I say ‘freely’, I mean with cranks and pedals attached but no chain. Should it spin and spin?)
The reason I ask is b/c if I spin it by hand (no chain) it only makes a few revolutions before stopping. (It hasn’t been ridden yet) The XTR BB on my MTB is nearly 3 years old, and will spin forever it seems when I take the chain off to clean?
So, do they loosen up, or should I have a more experienced eye check the tightness before I ride it? Thanks.
The (9 speed) ShimaNO DA BB is a PITA for most people to set up properly. You may have seal drag, you may have it to tight. What I do when install that BB is use the “Barnetts” method of adjustment. I put 1 degree indicator marks on the cup and a mark on the BB shell…adjust out till I get play, then go back in one tick at a time (one tick equals 1/10th mm). When I fell it is tight, I back it out 1/10mm and tighten the locknut and feel for play. I try to have one crank arm on the bike as I can feel play better with a 170 some odd mm lever to better notice the possible play. This BB is kinda known for being a PITA and seemingly failing to soon (as opposed to the Ultegra cart. style BB). I think that this is not due to the quality of the DA (SEE THAT!!! I used QUALITY and DA in the same sentence!!!) - I think that the failures may be due to declining skill of bike techs as they get more and more used to the cartridge systems out there.