Outboard BB - Did You Reface the Bottom Bracket

[weaponsgrade]

I've got an older ti serotta ('99) that came with a square taper BB. I'm about to put in a new set of cranks with the outboard BB. Is there a need to have the bottom bracket refaced?

[Kevin Grady]

Over at cyclingforum.com we have had a couple of discussions related to both new Campy UT cranksets and BB cups. One of threads talked about making sure that BOTH sides of the bottom bracket have been properly faced, due to the close tolerances of new crank designs.

Sometimes older frames were only faced on one side, and that may work for standard square taper design, but not for the new through axle designs. I think the answer to your question is that it would not hurt to insure that your bottom bracket are is well faced to accept the new designs.

Kevin

[pdxmech13]

that frame had better facing tools on it in saratooga than anything you could have a shop due.

[Dave]

Beware of too much facing. You could make the BB shell too narrow and then require a spacer to restore the 68mm length. Campy provides a specific length tolerance.

Facing will keep the BB cups from comeing loose due to partial contact with the faces of the BB shell, but it won't guarantee alignment of the cups. The thread alignment has a greater effect on the alignment and really can't be changed. A thread chaser only follows the original thread.

Personally, I'd tighten the cups within about .010 inch of the shell and use .008 and .012 feeler gages to hunt for a high or low spot. If none exceed .002, I'd do nothing. A refacing might not improve the alignment. A skilled mechanic would put Dykem (a blue marking die) on the face and gently touch the cutter to the face to see if there was indeed a high area that needed to be removed. A hack would just scrap a bunch of metal off and call it good.