OK. Thinking of upgrading to a 7 speed. Sheldon Brown says the Shimano FW722 will work with my vintage bike 126mm spacing. Unfortunately he won't ship to Canada orders under $50. Does the Shimano FW722 have a different model number? I have seen the Shimano 7sd HG-37 13-28 and the Shimano 7sp MF-TZ21 14-28. Would either of those work? The HG-37 pictures look the same as the FW-722.