uncle uncle

I'm working with a college student who has a 1980 (or there abouts) Schwinn World Tourist 5 speed. They have never shifted the gears, on the fear that they are breaking something. I want to convert the bicycle to index shifting for them. Can I just get an indexed 7 speed thumb shifter (like one for a mountain bike), a new indexed five speed freewheel, and index compatible chain? I think I have a cheapy Shimano indexed derailleur around, like something that might have come on a department store quality bike. I can just lock out the last two clicks with the derailleur set screws... or will the indexing be off?

Or could I use something like this?
https://express.google.com/u/0/produ...qnyulq,4181969

curbtender

If you have a cheap 5 speed donor, yes. If you are using the five speed setup, then use the five freewheel off it.

degan

Clicking an indexing shifter pulls a specific amount of cable. 7 speed clusters are generally going to be more tightly spaced than 5 speed clusters because they need to fit more cogs into relatively the same amount of space. One click of a 7 speed indexing shifter pulls the perfect amount of cable (other mechanical issues withstanding) to move the RD/chain to the next cog if the cogs are spaced like a 7 speed. If they're spaced wider, like a 5 speed, one click isn't going to pull enough cable to get it perfect. It might shift, but will be constantly be rubbing and you'll get ghost shifts and the like. Some freewheels/cassettes randomly/magically have the exact spacing and can be interchanged. Shimergo, for example. Ergo brifters of some generation pair perfectly with some generation of Shimano RD/cassette and it's become a pretty common thing to combine them. There are other combos that work that I'm not as aware of off the top. I would see if they make a 7 speed freewheel that is spaced for your RD/shifter that you could just replace the current 5 speed one with. Or replace the whole wheel. 7 speed indexing parts are not generally highly sought after, so it might be a pretty cheap option.

If the question is will any old indexing shifter/RD index correctly on any old freewheel/cassette the answer is no.

EDIT: Just re-read and noticed you are getting a 5 speed indexing freewheel as well so you probably know all this. If the spacing is correct, it should work. As long as the RD limit screw is really dialed in. Don't want someone to be able to shift it up into the spokes looking for another gear while struggling up a hill.