There are four dimensions that determine pedal clearance: BB Drop, Wheel Diameter, Crank Arm Length, and pedal spindle length. The BB drop (vertical distance between a horizontal line drawn through the front and rear dropout centers and the center of the crank) of my 24" 1973 Super Sport frame is 75mm. On a production model like the Super Sport, the BB drop is the same for all frame sizes, so the remaining variables are the wheel diameter (including the tire size), crank arm length, and crank spindle length (the spindle length only comes into play when you're leaning into a turn).
On the Super Sport, the standard Astabula crank arms are 170mm. According to the Schwinn specifications, the same crank (p/n 56 018) was used on all frame sizes in 1973, the rims are 27", the tires are p/n 62 203 (27" x 1-1/4"), and the pedals (p/n 57 730) are all the same for all frame sizes.
So, no, there is no difference in pedal clearance between frame sizes on the fillet brazed Super Sports.
Putting 175mm crank arms on your son-in-law's Super Sport is probably not a good idea because of the higher risk of pedal strike.
__________________
- Stan
my bikes
Science doesn't care what you believe.
Last edited by Scooper; 08-29-12 at 08:41 AM.