That's an interesting topic and I've wondered myself what might be more dangerous. I think most of the posts here are hitting the nail on the head....whatever the correct answer might be. I rode and raced MX and desert (2-wheels) for about 10 years....then my parents fell on hard times and it became a thing of the past. During that time I had countless crashes but most not too bad as far as injury. The worst however, was a near fatal and it was due entirely to my own stupidity. I was play riding in unfarmiliar desert territory racing down a wide open trail with a friend. The trail turned into a gently upsloped hill where I thought I would enjoy some airtime.....I did with sixth gear pinned! Not too smart because I incorrectly assumed the trail continued in a straight path. The trail turned sharply on the other side of the hill and I had a one-way ticket to the desert floor. The air time was great but the landing sucked!! I fractured my wrist and arm, broke several ribs, dislocated my shoulder, tore the outer and inner ligaments in my knee, suffered a mild concusion, had mulitple deep gashes and puncture wounds from the desert vegitation I hit, and ruptured my splean.....all in one stupid crash! Lucky I was with someone or I would have been coyote bait. I was out of work and pretty much out of comission for months after that.

Anyway, that was quit a while ago and I am much smarter now. I also ride quads now though I think they are only as safe as the person riding them. I would have to agree that crashing a quad hard may be more dangerous because of the mass issue. I would also agree that quads are easier to ride so beginners may have a tendency to ride more above their skill level which makes them more dangerous. But I think the bottom line is to simply ride and have fun and learn from stupid mistakes like the one I made.

Uh Oh....no spell check. I'm in trouble!