i'm moving this question from the C&V forum to here for some insight:

I tried to swap out my Suntour 13T-21T 6 speed freewheel to this (http://harriscyclery.net/itemdetails.cfm?ID=782) 14T to 28T Shimano freewheel.

However, the width of the Shimano freewheel is such that the smallest gear rubs on the chain stay. In other words, the axel is not the first thing the chain stay hits, it is the smallest gear, which makes peddling difficult

Does this sound familiar? I suppose i need to find a suntour freewheel, or did i not crank down on the new freewheel enough?

Thanks.