Whenever I mountain bike, I expect to crash. And whenever I crash, I expect to break. Given that I've only really broken properly once, and that I've done maybe 500+ mountain bike rides it's fairly unlikely. Still, that's my mind at work, always weighing up the risks.
Whenever I road bike, I never expect to crash. I can happily descend at 50mph, sweep through fast corners without thinking of braking, and generally act as if I'm invincible and will destroy any car that comes into contact with me. This is because I've never come off a road bike. If I ever do, I expect it to hurt.
In Spain, mountain biking, I only crashed once. That was a triumph of hope over skill, as I hit a 12" step up at speed and my front wheel washed out. The best thing about the crash was the way my bike landed on its side, with the rear wheel still spinning madly, whirring away. The second best thing was that all the cuts, grazes and bruises were superficial.
Spain had indifferent weather, landslides, missing bridges, awesome singletrack and views to die for. It also had plenty of beer, tasty local cuisine (including goat and wild boar) and a very annoying bike with a leaky rear shock.
That was the mountain biking - for a while anyway. It's the road bike(s) for the next two months, as Land's End - John O'Groats is getting scarily close.