Originally Posted by
wphamilton
Not if you roll (shoulder roll is my preference). The impact is from primarily the force of gravity, a drop from X feet, regardless of how fast you're going when your roll is quick enough to not slide. Obviously there is a limit to that.
I would much rather fall forward than to the side because a low-side fall gives you no opportunity for a roll, and it usually happens more quickly.
In my experience if you're "thrown" from a motorcycle, you hit something and most likely the bike pivoted around the front wheel, throwing you up as well. You'd fall for a greater distance. But it's no mistake, the initial impact on level ground is primarily from the height of the fall plus force arising from friction at right angles to it. I know it's not intuitive to most people, but feel free to check up on me with a physics professor who's spent too much time crashing motorcycles or bikes, and/or also trained in some physical art involving tumbling.
You're postulating a flight path that approximates an airplane glide slope. That's just not what happens, some of that speed-added kinetic energy will increase the impact of the first contact with the ground, the proportion depending on the angle to the ground when you land. Your forward momentum remaining after the initial impact can also result in bouncing, btw. There's a reason that planes flare before touchdown, that angle needs to be precise to keep the forward momentum from being completely stopped by the initial impact with the ground, and to let it be slowed in a controlled manner. I don't know about you, but the control surfaces on my arms and legs really aren't up to achieving that angle.
On what planet is one likely to be airborne on a bicycle on level ground long enough to even consider separating from the bike? That's a pretty neat trick on earth.
I've had a couple of wipeouts on level ground at 20+ mph, and in both cases, it's been a condition where sand or dust made the road slippery. I was on the ground before I knew what happened. In one of those cases, it was quite clear that the handlebars hit the ground first, and absorbed much of the initial impact. I ended up with scrapes, light bruising and finished the ride home. Not sure how I could have done better other than by avoiding the sand in the first place.