Classic & Vintage - Maximum Cog for GS RD
Bikeforums.net is a forum about nothing but bikes. Our community can help you find information about hard-to-find and localized information like bicycle tours, specialties like where in your area to have your recumbent bike serviced, or what are the best bicycle tires and seats for the activities you use your bike for.
I want to get a freewheel for climbing and I would like recommendations on how large of a granny gear I can get. The RD is a third generation Campagnolo Gran Sport and the chainrings are 50/47 but I am looking for a 49/46 or less if there is such a thing.
This will be a climbing set-up, I will put on the freewheel, chainrings and a different chain if necessary for only certain rides, otherwise my 14-22 is fine for the flats of Illinois.
I thought I have read 28 teeth is the max but that may have been for Nuovo Record. A 32 would even be better for this old man, but I really don't think that is possible. Ideally, 14-18-22-28 would fit the ticket, is this possible?
My 1960 Gran Sport (second generation???) is rated for 14-26 teeth. I am rebuilding the bike as a 12-speed: 49-46 / 14-16-18-21-24-26, using an ultra-6 freewheel for my 120mm rear axle.
If you have cottered cranks with the 3-piece 3-to-6-bolt Simplex adaptor, you can go down to 45 teeth, and probably 44, in which case you run 47-44, reusing your inner chainring as your new outer. 6-bolt 157mm BCD chainrings are not plentiful, but there is a 52-45 set currently on eBay. With your relatively large proposed jumps on the freewheel (I had a 1971 SunTour 5-speed with 14-18-22-27-34 teeth), you may want to try 50-45 / 14-18-22-26, which should work fine with the Gran Sport.
I have always liked half-step / 1.5-step setups, in which I need change only the inner chaining to accommodate either hills or flats. In the 1970s I used 50-47 / 14-16-18-20-23 or 50-42 / 14-16-18-20-23, depending on whether my route included some serious climbing.
I am watching that very auction. You're not going to bid against me, are you?:p
I'm just trying to figure out what will work and what won't before I start buying everything that pops up. So you are saying there is no hope for a 28?
As for your RD, if it is from 1960, there should be no cable adjustment screw and the body is steel instead of bronze. These were made from 1960-1963 and are third generation, version 2. I think they also did something to strengthen the springs. Hi Campy's site rocks. http://www1.ocn.ne.jp/~campa/
Also, any issue with mixing aluminum and steel chainrings? CycleArt has a steel 48 for $12 that would match up nice with that aluminum 45.
I hate to bring this up again, due to previous fallout, but I routinely run a 28 on my Gran Sport bikes too.
Powered by vBulletin® Version 4.1.12 Copyright © 2014 vBulletin Solutions, Inc. All rights reserved.