The idea in itself doesn't sound that crazy: Take a motorcycle, remove the wheels, install a ski on the front and a track assembly on the rear then go romp through the snow like one of Santa's long lost adrenaline-junkie reindeer. Nothing to it, right? Actually, this wild winter pastime has evolved into a full-on frenzy among horsepower enthusiasts, and as a result the sport of snow bike riding is becoming a legitimate segment of the two-wheeled market. Except that it doesn't involve any wheels at all.We recently got a chance to shred some of the last remaining powder of the season on the four major snow bike systems that are currently in production. While the technology isn't flawless and there is still a lot of improving to come before the bikes are perfect from a performance standpoint, these puppies sure are a ton of fun to play on. From boon-docking across the backwoods to blowing up piles of snow and going up double-black diamond slopes, you would be surprised at what these machines can do. You'll see more on these wild creations in a future issue of Dirt Rider-probably in the Fall-but for now here's a sneak peak at what snow bikes are all about:Stay tuned to a future issue of Dirt Rider for full tests on all four of these machines!