A tall bike is a thing of beauty. Entirely unsuited to cross-town travel, the homemade monsters, in which a second (and sometimes third and fourth) bike frame is attached to the first, also have the noble quality of giving unseated riders a nice bit of airtime before they hit the pavement. No wonder tall-bike jousting is such a hoot. Similar wheeled contraptions will be pulled out of garages and stairwells today for the Tour de Fat Beer and Bicycle Festival. The fest, sponsored by New Belgium Brewery, benefits the San Francisco Bicycle Coalition and the Bay Area Ridge Trail Council. New Belgium calls it a "philanthropic cycling circus." The SFBC calls it "two parts bike rodeo and one part circus." What do we call it? Another goddamn way people on bikes insist on having more fun than the rest of us. Expect fire-jumping bike acts, cycling games, and lots of people encouraging you to drink beer (that's what happens when a beer company wants to put up a poster. Oh, and all profits from beer sales go to the nonprofits). Tour de Fat also has an impressive lineup of bands and performers, including Handsome Little Devils, the Asylum Street Spankers, Circus Contraption, the Sprockettes, and Lord Loves a Working Man. A costumed bike parade starts at 10 a.m. and the music starts at noon.