It's a banner year for beginner bikes! First came the all-new Honda CBR250R, and now Aprilia has announced that it will introduce this trick little RS4 125cc sportbike to the American market. Based on the Derbi GPR125 that leads the learner category overseas, the RS4 (for four-stroke) replaces Aprilia's outdated two-stroke RS125. With bodywork that closely mimics the line-leading RSV4 superbike, the RS4 also sets a new style standard for the beginner category. Rolling on full-size, 17-inch wheels and featuring an aluminum frame, asymmetric swingarm, 41mm inverted fork and radial-mount, four-piston front brake, the RS4 is a surprisingly high-spec offering. The fuel-injected, four-valve, DOHC single isn't going to set any lap records-our friends at_ Motor Cycle News_ in Britain report 13 horsepower and a 78-mph top speed-but that's enough to entertain any newbie, or even an experienced pilot looking for a light, sporty alternative to the ubiquitous commuter scooter.