Campagnolo’s early offerings in the world of derailleur gears were beautifully precision-engineered ‘Cambio-Corsa’ models with a characteristically ‘out of the box’ inventive design. This bike’s ‘single-lever’ mech combined the actions of the earlier ‘two-lever’ model. That is, firstly releasing the rear wheel to allow it to adjust for the different chain lengths needed for different sprocket sizes, then secondly, shunting the chain across these sprockets.
To change gear:
Make sure the rider behind has a safe gap to you, you’re about to lose speed as you freewheel.
Make sure you have a safe gap to the rider in front – your right hand will be too busy with the gear change to worry about control of your front brake.
Reach down and find the gear control lever behind your right knee.
Stop pedalling and rotate the lever outwards 45 degrees. This unclamps the rear wheel quick release and engages the chain striker. The wheel is now free to trundle back and forth in the dropouts. It’s kept in alignment because the axle has slots engaging with corresponding teeth in the top edges of the dropouts.
Important! Don’t pedal forwards – the wheel will shoot out of the frame.
With the control lever pointing outwards the mech has engaged with the striker plate embracing the top chain. Start back-pedalling and waggle that control lever to select the gear you want. Chain tension is automatically adjusted by the weight of the rider encouraging the wheel to walk back in the dropout if a smaller sprocket is selected, or forward (for a larger sprocket).
When you have the gear you need, stop back pedalling then re-clamp the wheel by rotating the lever so it’s forward-pointing again. The chain tension would be a bit high (depending on rider’s weight) so a natty bit of the design backs off this tension as the wheel is clamped. The striker has now been disengaged and is free to ‘float’ over the chain.
Resume forward pedalling (assuming you haven’t already come to a dead stop). Start making your way back into contact with the peloton.
In 1948 Gino ‘Il Pio’ Bartali took to the mountains of the Tour de France with a Campagnolo Cambio Corsa ‘Una-leva’ mech. A cumbersome change it may have been, but better than the ‘Due Leve’ suicide-shifter that preceded it and certainly faster than taking out the rear wheel then re-installing it the other way round to use a different sprocket.
Unfortunately Fausto ‘Campionissimo’ Coppi used the ‘Una Leva’ Campagnolo Cambio Corsa mech. when he won the 1950 Paris-Roubaix convincingly with a legendary solo break. The mech was immediately re-branded ‘Paris Roubaix’. It was very much in demand. How did Coppi do it? Well, Paris-Roubaix is gruelling but pretty much pan-flat. There hadn’t been much gear changing going on, he doubtless would have enjoyed the same success with a single-speed bike. Let’s face it, he time-trialled to victory.
The ‘P-R’ mech held sway with some time-trial devotees for a few years as it was lightweight, robust and above all didn’t incur any drag guiding the chain through the twin jockey wheels of a conventional rear hanger. But surprise, surprise, its tortuous operation never found favour in bunch racing. In 1952 Campagnolo saw the light and applied their precision-engineering prowess to the twin-jockey wheel Gran Sport mech which swept the board.
As purchased July 2017
As restored 2024
Matt Newton – JE James – Argos288640Bianchi chainring: 1/8″, 48 teeth.Headset and crown.Universal
