It's a mind control device imposed on unwitting cyclists that turns mild mannered MUP riders into careless daredevils who put public safety at risk with every waking second. Users have no control over or responsibility for their own actions and immediately become pariahs of their slow rolling bretheren. Side effects include spandex abuse, hair removal, overcaffeination, and increasing average speed. Many users have reported financial difficulties following their investments in ever lighter and more expensive bicycles. Beware, brother, beware!