Originally Posted by
mrrabbit
There's no need for the trial and error that has been suggested so far. There are clearly published specs:
Regular 5 and 6 Speed
A = 29.00mm for 5 Speed
A = 35.00mm for 6 Speed
C = 120.00mm-122.00mm
Narrow 6 Speed, 7 Speed and 8 Speed
A = 31.00mm for Narrow 6 Speed
A = 36.00mm for Narrow 7 Speed
C = 125.00mm to 127.00mm
I believe you have this a bit backwards. Narrow 6-speed freewheels (Ultra-6) were close to 5-speed in overall width and fit on 120 mm OLD hubs. Regular spaced 6-speed freewheels were close in width to 7-speed freewheels and fit on 126 mm hubs. 8-speed freewheels (the few ever made) were wider still and used 130 mm OLD hubs just like 8/9/10-speed freehubs.