So I recently came by a rather aged Clements 10-speed drop-handlebar bike. It sat in my parents garage for 15-20 years that I know of and possibly longer still, so needs a little TLC.

It's got shifter levers mounted on the stem and is very much a vintage bike in that it doesn't have nice indexing, you just move the lever and listen for the chain moving where you want it to be.

I'm curious how I'll get on with a drop-handlebar bike (I've ridden an MTB for the last couple of years) so I'm keen to fix it up to test it out. Then I can either keep it or sell it to fund something else.

I'm wondering what to do when the cassette wears out because I'm just not seeing 5-speed cassettes for sale. I can find 7-speed, but I'm not sure how well that will work with the existing setup. Am I right in thinking that if the cassette is comparable in thickness, and the tooth counts of the largest and smallest sprockets are comparable, then it should still work? I figure if I'm just shifting a lever until the chain moves then that should theoretically support any number of gears, as long as the rear derailleur is designed to move far enough to cater for them all.

Obviously I don't want to take a bike that might be worth something and turn it into a bike worth nothing if I can help it, so any pointers welcome!