The Cambio Corsa: Campagnolo's Early Masterpiece
Mon, April 26, 2010 
Necessity is the mother of invention, is the way the saying goes.
When Tulio Campagnolo stood on a cold mountain top, and couldn’t unscrew the wing nuts on the rear wheel of his bike because his fingers were frozen, he soon after invented the quick release hub.
This was back in 1930 and lead to the forming of the company that still bears his name today.
In 1940 Campagnolo invented the Cambio Corsa derailleur, which utilized the same quick release mechanism.
The now famous picture above shows Gino Bartali shifting gear with the Cambio Corsa on a steep mountain pass during his winning ride in the 1948 Tour de France.
For its time, the Cambio Corsa was a masterpiece of engineering, yet so simple in the way it worked.
There were no jockey pulleys to take up the slack in the chain as it moved between large and small sprockets.
Instead chain tension was achieved by the rear wheel actually moving back and forth in the rear dropouts.
Below are Tulio Campagnolo’s original drawings.
The standard sprocket width of that era was 1/8 inch, and there was no narrower chain available. This meant, at that time the maximum number of sprockets mechanically possible on a freewheel, was four.
Gear teeth were machined into the rear wheel axel, (Picture above.) these engaged in a rack consisting of teeth machined into the upper part of the frame’s extra long rear drop outs. (Picture below.)
This allowed the rear axel (When released.) to roll back and forth along the dropout rack, keeping the axel square with the frame. The wheel, although moving back and forth, stayed central within the chainstays.
The derailleur was operated by two levers on the right side of the bike’s rear seatstays, just below the rear brake. The top lever released the rear wheel, a lever below it operated a simple guide that moved the chain from one sprocket to the next.
Because this chain shifter was on the top portion of the chain, above the chainstay, it was necessary to back pedal to actually shift. The pull of the chain as it climbed over the teeth of the sprockets, moved the wheel forward. Once the shift was made, the rider’s weight automatically moved the wheel back and re-tensioned the chain.
Sound complicated? Actually it wasn’t as these videos below show the Cambio Corsa shifting down,
and shifting up.
The gear shift in the hands of an experienced rider is so quick, you will have to view these videos more than once to actually notice the rear wheel moving back and forth.
The videos are from Aldo Ross and can be viewed here.
Here is a link to the page showing how the camera was rigged to get these videos. People like Aldo Ross do a great service to cycling. Many will never see a Cambio Corsa derailleur, and even fewer would get to see one actually working were it not for these videos.
There are more pictures here, and more history here
Reader Comments (17)
Interesting history lesson, thanks. I do fear that Gino Bartali's fingers will get caught in the spokes of his rear wheel, though.
I may sound a little green but that is incredible! So simple and yet from the video it looks so effective and effortless. I've seen the system before but never had it explained so thanks for that Dave, you've brightened up a dreary Monday morning.
I had never heard of this type of gear changer till now. Interesting piece of engineering.
I saw a bike with this rig at a bike restoration shop here in San Marcos/Vista. Fascinating.
-Rob
Thanks Dave for another great history lesson on this early Campy shifting system. The videos provided a nice demonstration how smoothly it worked.
Wow - that was cool. Video allowed me to see how that setup actually worked.
This is great! I'd never heard of gear-shift derailleurs.
Excellent piece of cycling history, Dave.
I actually saw one of these just a week ago at a frame restorer's shop. He had three personal bikes that had this type of system. He took one down (hanging in the showroom) and I got to see first hand how the system worked. Truly fascinating.
So this clears up a mystery for me - I never understood why Campy manufactured dropouts. But it seems logical now that I've seen this shifting system in action. Great post!
Simple, elegant, effective. What more is there?
Utterly fantastic stuff Dave. Thanks.
Geniale ! Simple, straight-forward and very ingenious .
Not so simple, and far from elegant. Racks (dropout teeth) and pinions (axel gears) were frequently misaligned by builders, rendering these useless. Wear to teeth, over or undertightening qr led to breakage of the levers (they were very long and skinny). Elegance is beauty in simplicity and intuition when it comes to cycle design, and this system lacked all of that. So much that Campy lost market share to Simplex derailleurs in a hurry. Their "improvement with the development of the single lever {Paris Roubaix system was even worse. Coppi cursed it!! Campy's final response was a quamntum leap - the development of the GS parallelogram gear, a design that influenced all for three decades to follow, an was, in and of itself, quite elegant!
Something can be cool, interesting, and Campagnolo, but that doesn't make it any good!
BTW. The Cambio Corsa gear was developed in the 30's. The first versions had round section lever handles with knurled rings. Very much like the early QR levers. Good luck finding one.
What's interesting about this is that the system remained in use for over 20 years. I have two bikes with it, one from '47 and one from '55. The reason it was 'popular' at least for some time, was that some racers believed the pulleys in the derailleurs added too much friction to the system. When set up properly (and this presents challenges that we're not accustomed to today), cambio corsa does work quite well. I suggest giving it a shot if the chance presents itself... it's not that tough once you understand it. Just don't pedal forward with the wheel qr over!
I just picked up a bike that my wife's uncle built in Italy that has the Cambio Corsa system on it. In the process of restoring it.
Isn't Gino using a Vittoria Margherita derailleur in this picture?