The Tour de France is on again, once again putting cycling in the evening news.
Just a couple of weeks ago we were in Auckland, where a couple of our friends were holding a garage sale of their surplus bicycle stuff. There were at least a dozen vintage bikes for sale, as well as bins full of parts, and tables covered with accessories.
I was only there for moral support. Fortunately, my mates are both too tall for their excess bikes to fit me. I already have plenty of old junk that used to be cool, and while quite a few things in their old junk piles were well on their way to being cool again, they were not cool enough to tempt me.
However, and this is the Tour de France connection, I kept coming back to gaze at a bike that is not for sale. It is a Benotto, built in Italy around the time of the second World War. It is immaculate, with complete period parts, and painted a fetching olive shade. With an unlikely dark blue accent that shouldn’t have worked but looked amazing.
The other thing about this bike that shouldn’t have worked but looked amazing was the gear change system. Called Cambio Corsa, it was an attempt by Tullio Campagnolo to develop a multi speed drivetrain before he produced a parallelogram derailleur, the fore-runner of what most of us use to change gears today.
The Cambio Corsa works like this: Two levers on the seatstay (the tube running from the rear hub to the seat junction) operate the system. Right there is the first issue: to change gear the rider must reach down behind their right leg and fumble around near the spinning rear spokes. Finding the first lever, they flip it over. This releases the rear axle from the frame! Yes, you read that correctly. With the quick release open, the rider adjusts the second lever, to push the chain onto a bigger or smaller sprocket.
Today’s derailleurs take up the difference in the amount of chain needed for a different sized sprocket by means of a spring loaded pair of jockey wheels. With Cambio Corsa the chain or gravity moves the wheel backwards or forwards in the bike frame. Shifting to a bigger sprocket requires a bunny hop. Then the rider re-clamps the axle to race onwards. The wheel stays in line during this episode because the axle has slots cut into it that correspond with teeth in the frame. It sounds awkward and elaborate, and it is!
Gino Bartali won the 1948 Tour de France using this technology, and Fausto Coppi, one of the giants of cycling, rode what many consider to be among the best exploits ever when he won the 1950 Paris-Roubaix.
We don’t know how many functional Cambio Corsa setups exist in New Zealand, but there can’t be many. The owner of the Benotto performed a gear shift on demand, but he had to ride up and down the road several times to make it happen. While we watched him do it, it was suggested that Coppi probably planned his gear shift locations before the race.
It definitely wouldn’t work for trail riding.