Please allow me to add just a bit to the thread:
1) Thread sizes: In mm (according to Sutherland's 4th): ENGLISH: 34.80 mm x 1.058 mm FRENCH: 34.7 mm x 1.0 mm. ITALIAN: 35 mm x 1.058 mm
So, if you have a French-threaded hub, an Italian or even English will be a very sloppy fit. It doesn't engage the threads very well, particularly when you consider manufacturing tolerances. One of my sad memories is coming upon a rider on a lovely bike with Campy components near the top of a long, high, pass in Oregon, in the mid-70s. The relatively inexpensive FW (steel threads) had just sheared of the aluminum threads on the expensive hub of an expensive wheel. Low gear ==> high torque, eh? So, if you're going to do this, do it on the flats, use a corn-cob 13-18 FW and huge chainrings, and don't let anyone young and strong ride it.
2) Interchanges. There are two problems with changing cogs on most vintage FW. The first is finding good replacements; the outer ones get worn out first for most users. The second is that most pre-Suntour FW had rediculous threaded cogs, with the two innermost Left Hand threaded. Rust-in-place design (Cyclo was an exception). On the other hand, once or twice a year I do a body transplant, particularly with two-slot Regina FW: disassemble the otherwise good FW, and replace the chewed up body with a new 2-slot or splined one.
3) Rethreading the hubs from English or Italian to French, if hub threads are shot. This is conceivable, but would be really hard. After taking the wheel apart, you'd spend a lot of time jigging to get the hub centered for the lathe. And, you'd have to be careful that enough meat is left to support the bearing cup, etc. All that might be easy compared to finding a new French-threaded FW in the US.
But, I'd love to be wrong on some of this.
harvey sachs mcLean va
Billy Ketchum noted: Hi Pablo. I think an English or Italian threaded freewheel will fit a French threaded hub even though Sutherland's says they won't. And yes it is possible to replace the cogs on virtually any freewheel if you have the right replacements. It's also possible to repack the bearings, often w/ delightful results. A lot depends on how seized up parts have become.
Pablo Brena asked: I've read ?that it is possible to re-thread parts like BB or Cranks, but what about Hubs? If its not the case... how about French threaded freewheel (say 5 or 6 Speed) availability... and Cogs??? is it possible to replace worn out ones and/or custom build the cogs sequence???
Regards,
Pablo Brena
Mexico, Distrito Federal.