swap out 5 speed for 6 speed?

[ParkRNDL]

My daughter has a nice '76 Collegiate 5-speed that she doesn't ride much because she doesn't like having to reach for the stem and hunt for the gears when shifting. She likes the 3-speeds I have much better because she can just click to shift with her thumb. So I was stripping a couple of old junker hybrids for parts and I got an idea... take the SIS thumb shifter and rear derailleur from one of them and swap it onto the Collegiate. The ones I have here now in my parts stash are both for 6-speed rear clusters. Can I just swap a 6-speed cluster onto the Collegiate wheel and go from there, or am I going to have spacing problems?

 

[wheelbender6]

That should work. Swap out the shifter, derailleur and cogs, as you said.

 

[Karate Chicken Industries]

I've converted 5-speed Schwinns to 6 speed that way and it works fine. You may need to get a chain, depending on the freewheel used.

 

[AndyA]

If your daughter wants a thumb shifter in lieu of the stem shifter, just switch the shifters. No need to mess with the cogs or derailleur. A friction shifter for 6 cogs will work fine for 5 cogs. Friction shifters are readily available. If you have a 6-speed index shifter, it might or might not shift well with 5 cogs. In that case, I'd give it a try. Some index shifters are convertible to friction.
Have fun.

 

[Duchess]

I've converted several bikes from stem shifters to thumb shifters using stripped parts from old handlebar shifters as handlebar mounts to move the stem shifters to behind the grips to work as thumb shifters and just getting new cables.

 

[RustySprockets]

Be aware that Schwinn 5/10-speeds of that vintage often used a cable with a Huret/Simplex radial 'lolipop' end, rather than the common modern axial barrel. Save that part from the donor bike or get a new inner to use with your thumbie.