Ubrake

Ubrake, in the context of bicycles, refers to a type of rim brake most commonly associated with BMX bikes. The design is characterized by two brake arms that pivot on posts mounted to the frame and extend toward the wheel from opposite sides, creating a U-shaped profile when viewed head-on. The brake pads are mounted at the outer ends of the arms and press against the rim as the brake is applied.

In operation, a cable system connects to a central link or yoke that coordinates the movement of both arms. When the rider pulls the brake lever, the arms pivot inward, forcing the pads to grip the rim on both sides and slow the wheel. This arrangement offers strong braking power and straightforward single-cable actuation, though the exact routing and mounting can vary by model.

Mounting and compatibility for Ubrakes typically involve a brake bridge or specific stud posts on the frame near the rear dropout or seat stays. The setup is designed for frames that accommodate a U-brake via the dedicated bridge and corresponding mounting hardware. Ubrakes are not disk brakes and require compatible rims and clearance around the tire and frame to function correctly.

Historically, Ubrakes were common on mid- to late-20th-century BMX bikes and remain found on many older or retro-styled frames. They have been largely supplanted by V-brakes in modern BMX for several years, but continue to be used by enthusiasts who favor traditional setups or vintage builds.

See also: V-brake, caliper brake, rim brake.