Stationary bicycle trainers are an invaluable tool for cyclists who wish to stay in shape over the winter, or who even just want to work on their technique on rainy days. There are a variety of options available, including old school exercise bikes, rollers/resistance trainers that the cyclist's existing bike can be mounted on, or ... things like the Wattbike. Essentially a high-end indoor bike that is set up to replicate the feeling of riding a road bike as accurately as possible, one of the Wattbike's unique features is the fact that it measures and displays its rider's power output in watts - hence the name. Although it's been around in the UK since 2008, it is only now becoming available in the U.S.

The story began in 2000, when the founders of the company approached British Cycling (the governing body for British bicycle racing) about creating a trainer that "accurately measures a range of high-performance parameters." After six years, British Cycling was satisfied that the Wattbike met their standards, and agreed to endorse it. The trainer has since become popular with elite athletes around the UK and Europe.

Along with seeing how many watts they're producing, riders can also use the Wattbike's performance computer to view their output in terms of energy (joules), speed (kph) and pace (time per kilometer). This and other data is gathered via 39 parameters that are recorded 100 times per second, and then condensed into seven different screen views. If riders want more information, however, the computer can be hooked up to a nearby PC that's running Wattbike Expert Software. Multiple trainers can even be linked into one PC, so they can race one another.

A heart rate monitor can also be added, as can the saddle and pedals of the user's regular bicycle. The device utilizes both wind and magnetic resistance.

The Wattbike is available in a basic Trainer version, and a more advanced Pro model. The Pro features a wider resistance level, and is intended for top athletes. Both versions sell for US$2,995, and can be purchased through the Wattbike US website.