Maximum Cog for GS RD
07-02-07, 03:39 PM
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Maximum Cog for GS RD
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?
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?
07-02-07, 08:59 PM
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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.
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.
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Capo: 1959 Modell Campagnolo, S/N 40324; 1960 Sieger (2), S/N 42624, 42597
Carlton: 1962 Franco Suisse, S/N K7911
Peugeot: 1970 UO-8, S/N 0010468
Bianchi: 1982 Campione d'Italia, S/N 1.M9914
Schwinn: 1988 Project KOM-10, S/N F804069
"Far and away the best prize that life offers is the chance to work hard at work worth doing." --Theodore Roosevelt
Capo: 1959 Modell Campagnolo, S/N 40324; 1960 Sieger (2), S/N 42624, 42597
Carlton: 1962 Franco Suisse, S/N K7911
Peugeot: 1970 UO-8, S/N 0010468
Bianchi: 1982 Campione d'Italia, S/N 1.M9914
Schwinn: 1988 Project KOM-10, S/N F804069
07-02-07, 09:17 PM
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I am watching that very auction. You're not going to bid against me, are you?
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. https://www1.ocn.ne.jp/~campa/
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. https://www1.ocn.ne.jp/~campa/
07-02-07, 09:24 PM
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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.
07-02-07, 09:24 PM
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I hate to bring this up again, due to previous fallout, but I routinely run a 28 on my Gran Sport bikes too.
https://www.classicrendezvous.com/Ita...gn_TW_rear.htm
https://www.classicrendezvous.com/Ita...gn_TW_rear.htm
