In a message dated 10/16/2002 2:47:15 PM Eastern Daylight Time, Bob170871 writes:
<< A friend of mine was told that when assembling a new bike, the bottom bracket shell is often out of alignment, and as a routine matter the shell should be faced using the appropriate Park or Campy tool. His source maintains that this needs to be done even on the highest quality framesets, ie; Colnago, DeRosa, Litespeed, etc.
This seems to me defy logic. If Colnago cannot get the bottom bracket faced properly, how can a bikeshop using a fairly simple hand tool ever hope to do it? Furthermore, although the Italians make some fairly laughable autos, they make some of the finest machining and gauging equipment on the planet. It would seem that one of those machine builders would be happy to built them a machine that would hold NASA specs if necessary.
If the information my friend got is correct, should I take my Colnago, my Pinarello and my Guerciotti and remove the bottom brackets so I can have a local bike shop face the shells? They were all originally sold as built bikes from the makers, so I'm pretty certain the bottom bracket shells have never been faced by anyone other than the builders.
I'm a regular at the May rendezvous in Greensboro and I'm looking forward the 2003 show. Last year I bought an Eddy Merckx frameset which I have yet to fully assemble. Heck, there is another bottom bracket cup that may have to be faced! Thanks, Bob Sutcliffe, Lansing, Mi. >>
Hi Bob:
Funny, I did a column about this exact topic almost 30 years ago in the LAW magazine..
Colnago himself wrote afterwards and defended himself with some Cock N Bull story about how in Italy and Europe, the Pro bike shops insisted that they be left that operation as part of their involvement of bike preparation...
The truth is that the shell is usually aligned very well, but the outside face and inner threads are not cleaned up after the sloppy brazing/building process. By the mid 1980s Colnago tried to diminish that by putting threaded aluminum throw-away cap pieces in the BB shell during manufacture but it still was rough.
Here's the real deal:
1) A thread chasing/cleaning tap should be run through the threads to allow smooth fitting of the BB cups. Yes, a determined 1/2 assed mechanic can often force the cups in without that, but it is not optimum and an affront to a quality frame.
2) The bb shell outer flats need to be "faced" or shaved of miscellaneous gra-doo (paint, metal bits, solder, etc.) but ONLY if you are using a traditional bb unit which has lock rings and/or shoulder as part of the design.. Some newer style bb's do not have this so it doesn't matter if that outer face is flat or not! If you do have lock rings etc, the adjusting and tightening up of the bb on a not-faced shell, can pull things out of square and deteriorate the smooth running and longevity of the BB unit...
Clear as mud? <g>
Dale Brown
cycles de ORO, Inc.
1410 Mill Street
Greensboro, NC 27408
336-274-5959
fax 336-274-6360
http://www.cyclesdeoro.com
http://www.classicrendezvous.com