I've never heard of a 171.5 crank....
Imperial measurements nosed their way in. Its design is as a 6 3/4" crank (=171.5mm)
I have a wierd SR crank from a '80 Schwinn WS that uses a long spindle like that. Also has a 118mm small ring BCD and the large ring is something ginormous (above 151)
__________________
72 Frejus (for sale), Holdsworth Record (for sale), special CNC & Gitane Interclub / 74 Italvega NR (for sale) / c80 French / 82 Raleigh Intl MkII f&f (for sale)/ 83 Trek 620 (for sale)/ 84 Bruce Gordon Chinook (for sale)/ 85 Ron Cooper / 87 Centurion IM MV (for sale) / 03 Casati Dardo / 08 BF IRO / 09 Dogma FPX / 09 Giant TCX0 / 10 Vassago Fisticuff