endo n. 1. a bicycling accident in which the rider is thrown forward over the handlebars. 2. an intentional bicycle stunt which lifts the bike’s rear tire off the ground. Etymological Note: Perhaps from end-over-end. (source: Double-Tongued Dictionary)
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This word also refers to a trick performed on a bicycle or motorcycle in which the rider balances on the front wheel, with the rear wheel in the air.
You’re right. I’m working on the second sense for this word; I think the first cite above is unclear, and probably belongs to your definition of an endo, and not to the one I have here.