Doug Van Cleve writes:
> I am getting ready to respace my 126mm Campy rear wheel to
> 120 and it would be helpful to know what the dimension is
> from the outer edge of the hub shell to the outer edge of the
> locknut on the freewheel side.
30 mm, from the shoulder that stops the freewheel from threading on any further (near the spoke flange) to the outer face of the locknut. This is given as 29 mm on p.92 of Catalog 17, but most hubs I've measured were 30. Even 30 mm is tight on most frames; On some frames, the domed seat stay ends aren't flattened or ground down on the inside, so extra space is needed on the axle, to avoid the chain hitting the seatstay when shifting. Any extra space there increases the dish of the wheel though, weakening the wheel, so keep it to a minimum.
Some brands of freewheel are wider there, so if your Cyclo-Pans (for example) causes the chain to rub on the frame, try a Regina, they're among the narrowest of the old style 5 speeds (not talking about "Ultra-" anything). Just 1 or 2 mm narrower than some other popular brands, but sometimes that's enough to keep the chain from hitting.
That 29 or 30 mm dimension was not a standard in the classic era by any means - you'll find many brands of hub were quite a bit wider there even for 5-speed freewheels. Just one of the reasons why Campy was considered the best - they sweated the details like this (minimizing wheel dish).
Mark Bulgier
Seattle WA USA