HEADSET:
Stronglight D6 - threaded headset - 25 mm x 1 mm (25.4 TPI) French thread - aluminum alloy construction - Clear anodized finish - 5/32" or 3.96875 mm ball bearings with metal retainers (...44 count total at 22 each upper and lower) - aluminum alloy upper and lower bearing cups with high tensile strength pressed steel inserts - chromium steel head race - 26.4 mm chromium steel crown race - aluminum alloy top lock nut and "keyed" washer - model D6 extra légère ... [For model year 1977, Peugeot PY-10 CP custom ordered bicycles came equipped by default with a Stronglight S5 Super Competition headset. However, one could also optionally specify factory fitment of the recently announced Stronglight D6 extra-légere headset as seen here. The S5 Super Competition model had been introduced to market back in late 1972 and was Stronglight’s very first reversed cup and cone design (...its P3 and V4 Competition predecessors both used "V" profile upper and lower bearing cups) intended as a direct competitor to the Campagnolo Record headset. It was initially made available having a satin chrome finish, but that was quickly dropped in favor of a more traditional polished chrome look. And while the S5 Super Competition would ultimately prove itself to be a highly durable component, it also had the distinction of being one of the heaviest headsets on the market at that time, weighing in at a stout 225 grams. Debuting at various end of year trade shows in 1976 for general distribution during model year 1977, the Stronglight D6 extra-légere headset was quite literally a part for part design equivalent of the nickel chromium plated steel S5 Super Competition, but one which was manufactured of lightweight aluminum alloy excepting the upper head race and lower crown race which were crafted from high tensile strength chromium steel. The net result was a racing oriented unit that tipped the scales at a much more respectable 125 grams (...and that measurement takes into account a full complement of precision steel ball bearings) and which was used on all of the 1977 season Peugeot-Esso-Michelin team bikes including those which Bernard Thevenet rode to victory that year in the Tour de France. The D6 extra-légere headset would continue on in production as Stronglight’s premier race oriented offering until being superseded in 1981 by the D8 extra-légere model which is identical in its external appearance to the D6 but which features a revised internal bearing geometry as well as physically larger ball bearings intended to extend service life with only a nominal increase in component weight while at the same time incurring but a minimum re-tooling effort.]
