I tried to transplant a set of pedals off a '73 Varsity (with one-piece-crank) on to a bike that takes standard threaded pedals...the size of the threaded pedal spindle was too small!

Is there Standard, French and Schwinn OPC sizes?

Standard = 9/16"
French = 14mm
1 piece crank = 1/2"

thank you!

can I swap spindles from 1/2" to 9/16"?

**edit**

I suppose thats a pretty silly question...because WHY? nobody would ever really want to.

I dunno. You'll have to try it. And it's not silly, you could just happen to really like the smaller spindled pedals.

with a pedal that came with all three sizes (something like the Atom or a Lyotard, maybe) I'm pretty sure it could be done...going from one brand to another an expecting the spindles to work...probably not, but you're surely not the first to try this. Actually a lot of BMX pedals come in both 1/2" and 9/16".