I wrecked my baby...

[psyber_0ptix]

Glad someone pointed this out. IMO it's NEVER a good idea to dump the bike. You don't stop faster that way, or avoid additional harm. In any accident your best bet it to ALWAYS stay on the bike and apply massive braking. You may hit something but the amount of Kinetic energy in your body (1/2)m*v^2 will be significantly less than if you dump.

Think about it. KE is a function of V squared. Going 50mph versus 30 mph is 2500 vs 900. Almost THREE times as less and not even half the speed. Just .02 from an engineering student.

Glad you're ok.

i dont understand....

your explanation is a bit arbitrary

He said there wasnt enough time to stop. Obviously there is no way to reconstruct this but randomly spitting out Kinetic Energy proves nothing. The point is take a full hit running into the truck (even if slowing down very very very slightly) or bail. There are far too many variables to state "stay on the bike" as the end all answer.  Experience is the biggest player in instinct. If he knew his bike could make it, i'm sure it may have been a different story.

What your arguement is missing:

actual Velocity of bike
coefficient of friction between the brakes and rotors
coefficient of friction between tires and ground (and if surface conditions are constant)
distance from UPS truck + other obsticles


edit:
and keeping in mind that the accident is an inelastic collision; and that your body cannot be added to the mass of the bike (except when calculating normal force) so while it shares the same velocity it carries a different momentum. (i.e. in this system you cannot be considered part of the bike if collision occurs)

but then again....physics isnt my major

[A_Steel_Horse]

Glad someone pointed this out. IMO it's NEVER a good idea to dump the bike. You don't stop faster that way, or avoid additional harm. In any accident your best bet it to ALWAYS stay on the bike and apply massive braking. You may hit something but the amount of Kinetic energy in your body (1/2)m*v^2 will be significantly less than if you dump.

Think about it. KE is a function of V squared. Going 50mph versus 30 mph is 2500 vs 900. Almost THREE times as less and not even half the speed. Just .02 from an engineering student.

Glad you're ok.

Ah, physics. Always rears it's head in automotive forums, equally in sports cars as motorcycle forums. I'm not a physics major or engineering student either, but it's pretty apparent that in most situations, you double the speed, you quadruple the forces acting on it. This applies for horsepower translating to acceleration (why a 400 hp car doesn't accelerate 2x as fast as a 200 hp car), wind resistance (roughly 4x the drag for 2x the speed) and collisions. But you're suggesting that he should have it the object at lower velocity rather than slide at a higher velocity. I'd agree with you if it was a given that he would collide with the object, but if there's a chance he would avoid hitting it, then it *might* be possible that sliding is the better option. Or not. We can't know because we weren't there.

What is misleading about your suggestion is that it doesn't take into account force transfer *over time*. A sudden stop transfers a hell of a lot of more kinetic energy to the object doing the crashing than a crash that incorporates crumple zones or friction. It's possible that the friction of his leathers/textiles against the road is greater than what he could have generated using braking. His braking would not have been ideal. So dumping very well could have slowed him more. Also, pressure = force over area. Colliding with a UPS truck on a bike could have led to "shaper" impact points than dumping, which could distribute the contact area over a larger area than just his head (I imagine him flying head first into the side of a truck). Let's say he dumped, the bike kept on going, clearing both his body and the truck. You've removed a 420 lb, pointy object traveling 50 mph from the net force transfer to the rider. Then his body hit the pavement and slid; now you have force transfer to the ground, not a truck. Finally he collides with the rear wheels of the truck which hopefully aren't rolling forward. Let's say his hip, flank, legs and helmet hit the wheels. Depending on how much of his body was in contact with the pavement and the amount of drag his gear applied to the pavement, he may strike the wheels at less than 30 mph and he may do it over a larger surface area. Overall, that's a better scenario than having the wheel come to a dead stop at 30 mph and having him rocketing over the handlebars, hitting the truck cab or UPS van wall.

Also, a collision could have led to a "high side" dump, if he cleared the front of the truck (say, striking the wheel well) and we all know that a low side is preferable. Most spinal injury incurred in a motorcycle is due to the hips contacting the pavement, not to force applied to the spine via the helmet (British government motorcycle safety report)

I don't mean to start at war at all. I just want to give a counterpoint that "always staying on the bike" is the best option. Truthfully, I don't think he made the decision to dump or stay on the bike in the moment of the accident -- rather, it was probably a judgment he made in hindsight.

If you look at my posts and find the one about my accident on a Katana 750, flying off the bike and landing in dense foliage was a far better outcome than staying on the bike. But I didn't get to make a choice. It was in God's hands.