I bought a used 94 Norco Bigfoot, and noticed afterward that the rear cog had been swapped for a 5 speed freewheel, and the derailleurs and shifters for 70's SunTour friction based ones. I've decided that I like the old SunTour parts, so I'll have to stick with a freewheel hub. But I'm wondering what I should know about upgrading the rear cog for 6 or 7 speed.
Usually the question "can i upgrade from a 5 to 7 speed" is met with "not without a lot of work, because the 5 speed is 6mm narrower" - but the original bike (according to Bikepedia) came with a 7 speed cassette.
Will this be as simple as removing the old freewheel and dropping in a new one? Or am I opening a can of incompatibility if i start monkeying around with it?