Well, the eBay seller of the Motobecane mixte (what I think is a 1979 Mirage) described the BB threading as "English". No. It must be Swiss. %&$*! I should've know better. That said, the seller of the bike (a well established vintage bike shop in New England) should've known better than I. Anyone need a brand new Velo Orange 107mm BB in BSA threading?

I installed the French BB in the Jeunet and then the Stronglight 93. It's really close, but I think 107mm is just about perfect. Here are some pics. My math was just about right on. As Jesco says, "I ain't all the way crazy!"