Originally Posted by
HillRider
The '08 Trek Madone has a large diameter, wider bottom bracket shell that uses the same bearings as "external bearing" bottom brackets (Shimano Hollowtech II, Campy UT, etc.) but dispenses with the threaded-in cups and accepts the bearing cartridges directly into molded recesses in the shell itself. It's semi-proprietary as it uses the same bearings as the crank makers but doesn't need the bearing cups.
Yup, I was fiddling with one at the Tampa Trek Store and it looks sweet. They told me it was proprietary though. Kind of makes it look like the bb shell and the crank are one.