Originally Posted by Road Fan

Anybody here have good results putting a square taper spindle into the OEM Raleigh/Brit 26 mm BB cups of a 1952 Rudge Aero Special? Are there combinations that do not work? I'm daydreaming of a vintage TA spindle with a Stronglight 49D or a vintage TA Cyclotourist crankset. I'd either use 48 tooth single chainring or a some kind of granny crankset, 48/32 or 48/28, perhaps. I would need to add a front derailleur, and some sort of chain tensioner in the rear.

Another opportunity might be an Avocet spindle with an Avocet crankarm set with a single or double (big with granny).

Known BB incompatibilities: 71 mm width versus 68 mm standard; 26 threads per inch original theading versus 24 threads per inch "modern" threading.

Goals:
get clean bearings into the BB,
eliminate the future hassle of non-destructive cotter extraction,
save some weight,
target 170mm crank arm,
option to provide for a granny gear with AW or FG hub.