If you look at something off the trail you WILL ride into it….
Forgetting to put the piston spreader widget in the caliper when bleeding your brakes, then pumping said brake, will result in brakes feeling very, very squishy and a drip-drip-drip noise as fluid hits the floor…. not that I have ever done that, no, not me….
SPD's – As a new user, no matter how much you practice on your drive / back yard etc, you will fall over at your first stop on the trails, having completely forgotten you were clipped in….