FW: [CR]Re: Backwards BB

During my frame building years I sold many Campagnolo triple cranksets, I am pretty sure they never made a BB set with the labyrinth seals. Because the bearing races are spaced wider the strength of the BB axle is higher. Maybe the extra length for the triple axle was just too much for the NR type seals.

When I worked at Specialized we designed and sold a BB set. I was in charge of this project, and we used Stanford University Engineering department for the testing. It turns out that the main load on a BB spindle is from bending, not torque. The finish was very important, any small grooves would lead to a crack and failure. Campagnolo spindles tested very well, but I have personally had them fail while riding. This usually happened while standing up and pushing hard, and would not be fun. I have seen the very sharp ugly broken spindle cut riders on the way down. So, it is best to be conservative when it comes to designing BB spindles. The new spline type BB's are much stronger.

Jim Merz Bainbridge Is. WA

-----Original Message----- From: classicrendezvous-admin@bikelist.org [mailto:classicrendezvous-admin@bikelist.org] On Behalf Of Stephen Barner Sent: Monday, July 15, 2002 1:02 PM To: classicrendezvous@bikelist.org Subject: [CR]Re: Backwards BB

I don't think the triple axle was ever produced in a NR configuration. I always wondered about this, as I thought tourists would benefit more from the self-cleaning effect of the rifling than racers, whose bikes get torn down for maintenance more often.

I replaced the Campy BB on my P15 with an Edco sealed unit, but got less than two years out of it. I was especially disconcerted by the fact that the distance between the point I noticed that there was a problem and total failure was only about 12 miles. I switched back to the Record tripple BB and have never had a problem. My experience has been that you can ride a standard BB with bad bearings hundreds of miles without a problem--maybe thousands.

Track BBs also had no rifling. I used to commute on my track bike and everytime it rained I had to rebuild it. It must be the fenders on the touring bike that protects its BB.

Steve Barner, Bolton, Vermont