Originally Posted by
thenomad
I have Suntour 6 speed freewheel currently and I'm thinking that if I can get a 7 spee freewheel on there (I think the teeth may be hyperglide style) then won't I be able to run 7 speed indexed shimano DT shifters or barcons?
Yes, if you have 7-spd freewheel with Shimano RD & 7-spd shifters, it'll all work fine together. I did this exact same upgrade 20-years ago.
Going to 8-spd would be more difficult and require upgrading your hub to 130mm and re-dishing your wheel. Also getting Shimano indexing to work on that 8-spd freewheel of unknown spacing may be difficult. I've had no problems with Sachs 8-spd freewheel though.
If you paln on staying with your Suntour shifters & RD, then friction is the only way with either 7- or 8-spd set-ups.