Subject: RE: Bottom Bracket Woes I found this on the web at the following address: http://www.spectrum-cycles.com/64.htm
Bottom Brackets
The Chorus and Record bottom brackets are effectively the same units with some material differences.? Two bearings on the drive side and one on the left.? Traditional four sided taper spindles.? Shimano's Dura-Ace bottom bracket is lighter and stiffer than either Campy BB or the Ultegra bottom bracket, but it does have a tendency to wear out faster than almost any other on the market. The reasons for this annoying problem are seals that don?t work very well and needle bearings that begin to dig into the spindle surface during hard riding.? Most strong riders can not expect to get more than about 5,000 miles from a Dura-Ace bottom bracket.? The easy fix is to use the Ultegra bottom bracket with Dura-Ace cranks.? NOTE OF CAUTION? - If your bottom bracket threads are not perfectly aligned with each other, you will have immediate bearing problems with the Dura-Ace bottom bracket which can not be solved without replacing the bottom bracket shell. It is NOT the fault of the bottom bracket, but the bearing design requires perfect bottom bracket shells. Older designs were more forgiving of alignment problems. The Dura-Ace 10 bottom bracket is completely different from the others on the market. The oversized spindle is a permanent part of the right crank arm. The two bearings reside outboard of the BB shell like the old Magic bottom brackets did. Bearing adjustment is accomplished by tightening the left crank arm's center cap with a small supplied tool. Very simple.
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