It all started when I wanted to replace the completely functional plastic-coated downtube shift levers on my old french road bike:
With some slick-looking shifters a friend gave me:
Should be easy, right? Just cut the existing cables, replace the levers and string a new set of shift cables… wrong.
The old shifters and threaded bosses on the frame were an unusual, non-standard thread, M5x1.0mm, which as far as I can tell mainly existed on 1970s French bicycles and is no longer made. The standard metric screws near that size are M5x0.8mm or M5x0.5mm (the same diameter, 5mm, but a different thread pitch). I knew from Sheldon Brown and previous work on the bike that old French bikes are “special” and, for example, one of the bottom bracket cups is threaded in the opposite direction from pretty much every other bike ever made. But I didn’t think this applied to even small-size, standard-looking screws.
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