Originally Posted by
Monoborracho
It lists a 5 speed rear freewheel with Heliomatic hubs. Those are unique hubs, but generally good. I would surmise that, if it has sat for 20 years, you've probably got low grade varnish in those hubs. Clean out the grease and bearings in the wheels with a good solvent and have them tuned up and lubed with some new product. Freewheels vanished for 7 speeds and beyond because it put the bearing inboard of the right chainstay to the extent that you could bend the axle with some heavy torquing. I toured for a long time on 7 gears in back with a 14-34.
While there is nothing really wrong with freewheels, there is something wrong with the Helicomatic. Unique they are, but good, not so much. Parts are virtually impossible to find, and while the repairs ostensibly easy to do, the proprietary tools involved are near impossible to come by. I'd replace it with a modern cassette hub (7,8,9, or 10, it doesn't matter to me what you do). While you're replacing the wheel, you might as well go to 700c, just in case you want to run a really narrow tire, or a really wide tire that isn't available in 27 inch.