I have a balance problem and am having issues with shifting using the stem shifters on my Schwinn Traveler that I fixed up. I put flat bars on it and switched out the brake levers.

More details: The rear spacing is 126mm. The stock freewheel is a Atom 77 compact 6 speed. I found a 7 speed freewheel that has the same compact cog spacing as the Atom and put it on from my local coop. It is obviously a little bit wider due to the extra 7th gear. The bike currently has Suntour AR rear and Suntour ARX front derailleurs. The rear derailleur handles the 7 speeds with no problem.

I have in my spare parts bin a set of rebuilt and working perfectly Shimano GS200 7 speed pod index shifters from around 1993.

I'm not so worried about the front shifter, even though its a 3 speed, I know it should work fine with the front shifter pod and just keep the derailleur lockout screws adjusted correctly and that should be fine. If I have to, I could put some slack in the front cable to allow for the difference in pull (road vs MTB).

The real concern is the rear components. I actually have an Acera Shimano rear MTB derailleur that I could replace the SUntour with but I really don't to do that. The thing that concerns me is the cog spacing for the 7 speed freewheel. Should a compact 7 speed compact freewheel have roughly the same spacing as a Shimano freehub cassette? If they do, then the rear index shifting should work. I just don't want to find out the hard way that it doesn't after doing the whole switchover.