Welcome to the new and improved Proflex / K2 Tech Forum!
My guess would be that those are MTB wheels with really small tires on them. Don't know where you'd get tires in that size though (do 650c tires fit a narrow MTB rim?) Otherwise, they could be 650c wheels (do those have the same diameter as mountain bike rims? The brakes line up well...) It wouldn't be too hard for a creative person to make a rear axle fit, but more likely, if the hub is too short, he just cranked the skewer down tight to make it work. For the life of me, I can't figure out what in the heck a bike like that is good for. Seems like the suspension would be way too inefficient for a road bike, the tires are too smooth for a cyclocross bike, and the wheels are too wimpy for off-road riding (haven't heard the best reports about such wheels). Oh, wait. I know - it's perfect for getting a good deal, then parting it out again on eBay! Depending on the reserve, you could actually make a decent profit off of it...
The fun to saddle time ratio is way better on the mountain bike!!!!!!!!!!!!!!!
True, but I feel a lot safer road biking alone than I do mountain biking. Therefore, when I want to ride alone (which more often than not means I just want to ride and nobody can go with me), I ride the road bike. A lot easier to get help if I crash, and crashing is a lot less likely!Plus it's hard to beat the feel of pure speed on a road bike. You can do it on a mountain bike too (even MORE fun), but you have to have really big hills...