This patent describes the Campagnolo Corsa, a nightmare system of beautifully chromed rods attached to your chain-side seat-stay. It works something like this:
First you drop out of the peleton so that you do not cause a catastrophic pile-up.
Then you twist the top lever. This slakens off your rear quick release.
Then you fiddle around with the lower lever while back pedalling in a hopeful attempt to force the chain onto the other of two sprockets that you have on your hub.
Then you pedal gently forward to 'position' the rear wheel.
Then you twist the top lever back to its original position to relock the quick release.
Then you sprint like crazy to try to get back onto the rear-most wheel of the peleton.
