Stuart Tallack asked:
Will the CR encyclopaedic knowledge satisfy my curiosity? How were the pretty octagonal tapered hollow Duprat cranks made? ++++++++++++++ In the chaos of conversations that marked Cirque, I chatted about this with either Joe Benden-Zanoni, Mike Kone, or someone equally knowledgable. The Expert claims to have seen them stripped of chrome, and to have found no indication of any assembly marks (welds or brazes). But, neither of us could conceive a plausible forging sequence that got us to the end point w/o some assembly. I still think that they are built-up from a forged shaft and two end pieces, but I'm not about to grind away the crank to look.
For those who don't know these cranks, they are beautiful. The shaft is octagonal, tapered, and hollow. The inboard end of the shaft is 13 mm across the flats (just above 1/2"), and they are only 11 mm at the outboard (pedal) end. It's all steel, with cotters (of course). Mine use a Stronglight/Williams 5-pin circle, don't know if they made a 3-arm version or not. My Duprat steel right arm weighs 3 gm (0.1 ounce) more than a TA Cyclotourist aluminium one, which is amazing to me. I've ridden with mine for about 25 years, and love them. Maybe this will motivate me to put some parts pieces on WoolJersey one of these days.
Regards,
harvey sachs
mcLean va