The Bike Winter Carnival, tonight at 7 PM at the Flat Iron Building (1579 N. Milwaukee), is both the closing party for the Bike Winter Art Show and the terminal destination for the February Critical Mass ride (starting at 5:30 PM from Daley Plaza). Performers include Schwinntonation, a band that “takes the various sounds that bicycles can make and turns it into music” and performance art group Environmental Encroachment, which “combines a costumed marching band with multi-media stage performance antics including dancers, hooping, juggling and skits.” A silent art auction will benefit the Flat Iron galleries, West Town Bikes, and the Chicago Women’s Health Center.