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INSTALLING NEW CAMPY RECORD BOTTOM BRACKET(3 posts)

INSTALLING NEW CAMPY RECORD BOTTOM BRACKETHURTKNEE
Feb 8, 2002 5:37 PM
THE MANUAL STATES TO FACE THE RIGHT SIDE OF THE BOTTOM BRACKET SHELL BEFORE INSTALLING. IS THIS NECSSARY AND WHAT EXACTLY DOES IT DO.

THANKS
re: INSTALLING NEW CAMPY RECORD BOTTOM BRACKETCT1
Feb 8, 2002 8:55 PM
This is generally not needed on a new frame.

However, I usually lightly sand down the paint on the drive side BB face. I use 400 wet/dry and a very flat A plate. Removing the paint (or most of it) will allow the BB cartridge "edge" to bite into something more solid than soft paint.

Works for me.

YMMV
JohnG
re: INSTALLING NEW CAMPY RECORD BOTTOM BRACKETxxl
Feb 9, 2002 5:19 AM
"Facing" a bottom bracket involves attaching a cutting tool to your bike, and using cutting oil with it to hone the outside b.b. shell surfaces, shaving off little bits of metal until the two outside "faces" are flat and parallel to each other. It's usually followed by "chasing" the threads to clean up the metal you shaved off the outside. When you've done this, you can mount the b.b. bearing cups (in the old-style b.b.'s, anyway) on the b.b. shell so that their bearing surfaces rest in parallel planes to each other. This helps make sure the b.b. bearings carry the load the way they're designed. I've only seen this done on steel bikes; I assume you can't on titanium (too hard for all but factory tools), and I can't say for carbon fiber. I would guess you can also face aluminum frames, but again, no first-hand experience here. Also, the tool I've used does the cutting on both faces simultaneously, so I'm not sure what Campy had in mind.

As the other fellow said, most of the time this has been done already at the factory; occasionally at the bike shop, if they're building up a frame. But, sometimes, it just doesn't get done, particularly on lower-end bikes. And, if you've had a frame repainted, it needs to be done to get the paint off the faces and b.b. threads. BTW, the head tube also has "faces" that are similarly treated to seat the upper and lower cups.

If you're switching out a part, I'd guess you don't have to worry about facing. One other point: the cutting tool works amazingly easily, and if you go at it with too much gusto you can quickly convert your 70mm b.b. shell to a 68mm. Then, you have a whole new, albeit curable, problem.