Ugly -There are lots of ugly bikes out there. Some are also good bikes. As was pointed out you know a bike is ugly when a six-year old stops you on the trail and tells you how cool it looks.

Unified Rear Triangle -It's purely a matter of personal taste, but weren't these once considered the ultimate expression of the dual-suspension designer's art? Now it's just another choice, and maybe not the best one for high-performance riding. United States of America -It's our country. Love it or leave it, or I'll come over and blow up your trailer.

Unobtanium - describing a bike or accessory made from expensive, high-tech material. A play on "unobtainable" and "titanium."  a piece (of god knows what) that has come off from the inside of something else and rattles around, impossible to retrieve to stop the rattling. E.g. a piece of weld comes off of the inside of a bike frame.

USA Cycling - the umbrella organization for U.S. bicycle racing.

USCF - U.S. Cycling Federation, the organization that governs amateur road and track racing in America. A division of USA Cycling.

USPRO - U.S. Professional Racing Organization, the organization in charge of professional bicycle racing in America. A division of USA Cycling.