Any sports-oriented motorcycle modified with the intent of reducing weigh and increasing performance and improving handling. The term originally emerged in 1960s Britain to define the stripped and modified motorcycles ridden by the counter-culture 'Rockers', who would ride these 'café racers' along predetermined routes at high speed against the clock. Legend has it that a song would be played on the café jukebox, and the rider would have to complete the route and return before the end of the song. Many did not return at all. Original cafe racers of the Rocker era were largely based on Triumphs, BSAs, Velocettes, Nortons, Vincents, Moto-Guzzis and Ducatis - or amalgamations of multiple bikes, like Tritons and Norvins.
A café racer can also be a true-grit sport bike rider who rides hard and fast on the street. As defined by Dr. Hunter S. Thompson:
"A thoroughbred Cafe Racer will ride all night through a fog storm in freeway traffic to put himself into what somebody told him was the ugliest and tightest decreasing-radius turn since Genghis Khan invented the corkscrew.
Cafe Racing is mainly a matter of taste. It is an atavistic mentality, a peculiar mix of low style, high speed, pure dumbness, and overweening commitment to the Cafe Life and all its dangerous pleasures... I am a Cafe Racer myself, on some days - and it is one of my finest addictions." (Excerpt from "Song of the Sausage Creature")
"I put some lumpy cams and clip ons on my Norton this week. It's a proper café racer now."
"He'd ride that bike ton-up all day through the canyons. He's a real café racer."