This is a follow up to the whole reason this thread was started. I had my mechanic install a 7 speed 14-28 Shimano freewheel on my 1981 Pro Miyata. I think my mechanic is very good and he has plenty of experience with this sort of thing. He did get it to work, in part by gluing in a shim to lengthen (if that's a good way to put it) the extension of the Superbe derailleur. But I really didn't like the outcome. Both the big 28T cog and the small 14 cog were noisy. I've decided that I'm just asking too much with a 28 tooth and possibly also asking too much with a seven speed. I'm now in search of a 13-24 (maybe 26) New Winner cog set (or a whole freewheel).