# What are the vector forces that cause a high side accident?

I was accelerating my bicycle around a corner and leaning hard to the left. I felt my rear wheel hop and looked back to see what I had just hit. What I saw was that the bicycle had rotated such that the wheel had flipped from leaning to the left to leaning horizontally to the right. The next moment I slammed into the sidewalk. From tire hop to crash happened in a second.

When I saw the rear wheel had flipped from left to right, my immediate reaction was "How did that possibly happen?" I then hit the sidewalk.

Since the accident, I've been trying to understand how the forces the bike and I were experiencing ended up rotating the bicycle such that it rotated some 120 degrees to the right. The 120 degree is a guess assuming I was initially leaning 30 degrees leftward and ended up horizontal with my head to the right.

I described the accident to a motorcycling friend the other day and he said "Sounds like a high side to me." Looking at some motorcycle videos I would agree except they appear to involve braking issues and I was accelerating when the accident happened. Both accidents entail the rear wheel losing contact.

So two questions:

1. How do the force vectors end up rolling the bike up and over vertical when the rear wheel loses contact with the road? I would have expected the bike to slide such that my left side would hit the ground instead of the right side.

2. Did dropping my head to peek under my left arm pit to see what happened affect the forces and help flip me to the right? i.e., would my chances of counteracting the flip have improved had I kept looking forward?

• Would it possible to have a sketch added? Jan 17, 2020 at 18:12