Effervescent Spirits: "When a cork was popped, power was released. Bubbles escaped, the elixir went flat, no more "oomph" or energy. So, dropping your cork or having no more cork means you're out of it, flat, dead, pooped, no more stuff. Ergo, racers hang a cork on their bikes so they'd never be "out" of cork. There would always be one more effort left for a "jam" or sprint. Conversely, if a rider said he "uncorked" a sprint, well, he "jumped", "wound it up", and took off. Or, if he pulled their corks, he went so hard that the opposition got "dropped", "shook off" and had no more cork left.