... and why on Earth, you may ask, would you want to go slower? Well, because it requires more effort to make a slow bike go fast, and the more effort you put into your training rides, the faster you'll go when you swap in a regular front wheel on race day. That's the idea behind the new PowerWheel and SlowWheel, made by TriSport Devices.

The company compares the idea to drag chutes for runners, or weight vests for football players - it's resistance training.

The PowerWheel replaces a bike's regular front wheel and features seven levels of resistance, which can be adjusted using a knob on the hub when the bicycle is stopped. Its sister product the SlowWheel offers three levels, while both models also allow the user to completely turn off the resistance.

That resistance is created when a couple of rotating centrifugal masses in the hub pull on a cam as they rotate, the tips of that cam in turn coming into contact with an array of resiliently deformable blades. The faster the wheel rotates, the farther the cam is pulled into the blades, and the greater the resistance. When the user selects a higher level of resistance, the curvature of the blades is increased.

At speeds below 6 mph (10 km/h) the resistance is disengaged, to make both handling and starting from a standstill easier. It is also disengaged at speeds above 30 mph (45 km/h), as such speeds would typically indicate a downhill descent, which could cause the hub to overheat if it were engaged.

Besides its value on regular training rides, TriSport suggests that the wheel could also be useful for holding one's self back when training with a slower rider, or for maximizing the benefit of short-duration rides.

Richard Lewis, an independent inventor, came up with an interesting take on the same idea. His Gear-Head Cycling Trainer is sort of like a traditional resistance trainer that mounts on the rear wheel, except it has a gear reduction system that drives little rubber wheels of its own, so it slowly propels your bike forward while you pedal at high speeds in high gears.

The PowerWheel and SlowWheel concepts are currently on display at the Interbike trade show in Las Vegas, and are reportedly available for preorder, although prices have yet to be announced. Contact information is available on the TriSport website.