If I had land nearby to ride them on, I'd own a fleet of XR100's. I got hooked when I went to a dirt track school and they used them for training bikes. My reaction was the same -- those things are too damn small. After a few laps of tight oval and TT tracks, I was hooked. They make like 8 horsepower, but it's amazing to see what professional roadracers can do on one of those little monsters. Luckily, you can do incredibly stupid things (like trying to follow a pro racer) on them without hurting yourself too bad. They handle abuse from crashing really well. Once my 2 year old masters her tricycle, she's getting one. Of course I may have to borrow it from time to time.