Shimano RS rear derailleur-5spd to 7spd- will it shift ?
I'm upgrading a late '80's Puch 130. Got a nice pair of new alloy 27's at 126mm to replace the original steel wheels that are of the same dimensions. It was, and still will be friction shifted, but the shifters will be upgraded to Rivendell Silver Shifters. The original freewheel was a 5 speed Shimano, (14-28), and the new rear wheel is getting a 7 speed Shimano freewheel, (13-28). I'd like to use the original Shimano RS derailleur but if it won't function effectively I have no choice but to find a suitable replacement. The hangar claw is attached to the RS and runs in a straight arrangement without an angled attachment; and affixing is via axle/dropout. The Puch frame has no provision for direct mounting of a RD other than the original setup to the best of my limited experience. If it makes any difference, I'm using the original Sakae crankset that's a 53-43. Hopefully, that's enough info to enter a question or three...will the Shimano RS shift on all 7 freewheel cogs? If not, what RD do I need to find that will work, and how do I mount the thing; given the limitations of lacking tabs on a frame, and the tabs on the RD being sorta odd? I've read, and researched, and yootooobed, not finding much info, and no real answers. Hope the members here can fill in some gaps for me and educate me a bit as well. Look forward to any help provided and thanks to any who add their 2 cents.