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Threadless Bottom Bracket


The Grand Cru Threadless bottom bracket is designed to put that frame with stripped or unknown threading back on the road.

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.

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, a pin wrench, or the Park BBT-9. The BB shell does not require chamfering or facing; simply slip the BB into the shell and tighten.

Here's a video describing the installation process and here's an article on "Bottom Bracket Basics"

Note: not compatible with modern "Press-Fit" designs as the dimensions are completely different.

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