Grand Cru Threadless Bottom Bracket
Grand Cru threadless bottom brackets fit most frames, even those with Swiss threading. And they work on frames with damaged BB shells, even if the existing threading is totally stripped.
Unlike previous attempts at threadless BBs, this new design is "internally expanding". As the adjustable cup is tightened, the silver sleeve (see photo) is pushed up the tapered alloy cups, expanding and locking in the BB. This differs from older designs, like the Mavic, that pressed in from the outside and would sometimes slip. Installation requires only a traditional-style BB spanner or a pin wrench. The BB shell does not require chamfering or facing; simply slip the BB into the shell and tighten. It is easily removed and existing threads may be reused.
Like the other Grand Cru BBs, these have sealed cartridge bearings, so they require no servicing and should have a very long life. Taper is JIS. So far, we have tried these on British, French, and Swiss BB shells and they work perfectly. Customers report that they also work in Raleigh frames with a 71mm wide BB shell. These BB's won't work on mountain bikes, as their standard width (73mm) is too wide for the shell to expand. They do not work on Italian threaded BB shells because those have a wider ID.