What thread is the rear wheel axle nut? My father is trying to repair his old '65 (we think) Schwinn 3 speed. The only problem is he has not been able to get a replacement nut for the rear wheel axle. Local hardware stores have been unable to identify what kind of thread it has, and we've had no luck finding any info online.

Anyone know what it might be, or how/where to find out?
Your rear hub would have been manufactured by someone other than Schwinn. Given the age it was probably manufactured by Sturmey-Archer or Sachs (now SRAM). Those links contain links to small parts for both hub brands.

Sheldon writes:


  The axle threading of most SRAM internal-gear hubs is unusual, 10.5mm x 26 TPI, but close enough to that of many Sturmey-Archer hubs (13/32 x 26 TPI) that Sturmey-Archer axle nuts are usable in a pinch.