All photos are available in Whoops!
Couple of things here: First, I must admit fault for encouraging riders to stay wide on turns, particularly left-handers. The debris during this time of year can gather around the edge of the turn where no one is riding/driving (itself remedied if all traffic would keep off the yellow, but I digress) and in this situation it most likely contributed to the crash.
Second, upon studying his body position in the previous photos, it's clear that he's leaning off excessively and trying a bit too hard to get a knee down. Cut him some slack before you start ripping him apart in comments...I already said it. I figured out (eventually) that getting TOO far off the bike can take enough weight off the tires to cause them to start sliding, and sometimes it was best to keep the butt on the seat and let the road come to up to me...so to speak.
I had moved on to shooting other bikes when this crash began, so I didn't see or capture much except this shot, but I gather from the rider's account and the evidence on-hand, he started out wide and went to his full lean a bit early, and as the undulations in this turn made him push out a little wider, he didn't have the traction available to pull it in tighter and ran wide on the exit. He was fine, bike was lightly scratched where the poorly designed frame slider popped right off (OESaccessories beefy frame sliders people! ;) and he rode the rest of the day.
29 comments:
Glad you're ok!
Leaves! Nom, nom, nom...
Time for a quick physics lesson. Unless you're actually putting a considerable amount of weight on the road through your knee puck, you're not taking any real weight off the tires. It's not like the weight just disappears when you lean off.
The weight does however call down a different direction. A tire will hold tremendous weight verticly, it will not hold much in sheer. The lower you get the higher the sheer angle, the less the tire holds.
Let me add to said physics lesson. What you stated is true, but once the bike is leaned over to far parts of the bike touch down (on the road) taking considerable weight off the tires and then the weight disappears.
Hellbilly...that's true. But none of his bike other than the tires appears to be touching the ground.
Martvol...by leaning off, you are not, in any way, affecting the actual load on the tires. Only where it is applied on the tires. Unless you're running dual compound tires and you lean off enough to get the bike back onto the harder center compound (or don't lean off enough and somehow run out of tire before running out of ground clearance), the tires don't give a hoot how much lean off.
More than likely, this individual simply hung off too far to be able to adequately control the bike.
Beg to differ. lateral G's Look up how they work sometime.
Martvol, I'm very aware how lateral G's work. If you really understand how they work, you could put together a free body diagram of a bike in mid-corner to fully understand the cornering loads and how the movement of the rider affects (or rather doesn't affect at all) the peak loads at the interface of the road and the tire. You'll quickly come to the conclusion that unless the bike is already falling over, the amount the rider leans off of the bike has zero affect on the actual loads at the interface between the tire and the road. The only thing it will affect is what part of the tire the contact patch occurs at. This would matter alot more with a square, car-type tire. But since motorcycles have wonderfully rounded tires, it's really not an issue unless, as I mentioned earlier, the rider somehow managed to run out of tire before running out of ground clearance or leaned enough to get the bike back on a harder center compound.
If we're going to go to the trouble of recommending people go look stuff up, I recommend you go read through a statics book, and then move on to a dynamics book when you're finished. It'll give you a much better understanding of how these loads are actually calculated, what goes into them, and while you're at it, the dynamics class might help your billiards game too.
it would be easier to look at the girl from last highlights to see how its done. i think its the same corner. i told u its a tricky one. tryin to work that good pic could bite u.
Glad your alright!
looks like the steep down hill turn just after the state line to me.
Kinda looks like same r6 in above pic??
Hey Chris, welcome to the insanity.
"looking good" is KB code for about to crash in the next shot.
KB, please copy and paste your first paragrapph on this one with the picture at the top thats entitled "impressive line"...I will leave it at that, thats good..
When you corner like this. YOUR BIKE PUSHES DOWN HARDER ON THE PAVEMENT THEN IT WEIGHS. Now, like i said before if you push straight down on said tire with more weight, it will take it. Now push on the side and the bike will slide. SHEER. This is how wipeouts happen WITHOUT lifting the bike by puck or frame scrapping first. Now, like Killboy said, The flatter the thrust line is to horizontal on a bike the less weight is pushed into the road and more is held in sheer by the tires. There will come a point that the tire will no longer hold this sheer, the suspention will unload, and bad things will happen. So keep reading those books and taking those classes. You are almost there.
martvol,
Sorry but yeti makes a pretty good point. The cornering force is actually lateral or perpendicular to the road(excluding the slope in the pavement) The amount you lean over moves the center of gravity of the bike around and keeps the forces of cornering from making you rotate around that center of gravity(ala try turning a bike without leaning) The force that is verticle at the road is the weight of the bike and rider and only the weight of the bike and rider. You can't change that force by moving around on the bike. You can move the amount on the front tire vs the rear tire by accelerating or braking but since force = mass*acceleration you can't change the verticle force without accelerating in that direction(ie jumping).
Edit to previous comment... I meant cornering force is parallel to the road not perpendicular. Gravity is mostly perpendicular to the road. I also spelled vertical wrong but you get the point... the rest of it should be good info.
So dave, Are you trying to tell me that when you go through a corner you do not deflect your suspention more then going in a straight line? Newtons laws of Motion, as you tried to elude to, sates;
Law 1,An object at rest will remain at rest unless acted on by an unbalanced force. An object in motion continues in motion with the same speed and in the same direction unless acted upon by an unbalanced force.
This law is often called
"the law of inertia".
Law 2,Acceleration is produced when a force acts on a mass. The greater the mass (of the object being accelerated) the greater the amount of force needed (to accelerate the object).
Law 3,For every action there is an equal and opposite re-action.
Now, have stated that. Cornering force while while illustrated is an arrrow straight out from the center of a corner, your loads need to be transfered from one direction to another. This is done through the tire. To make a bike corner, as you stated we lean them, the tire then need to pick up the force from gravity, the weight of the bike. They also need to over come inertia to actual turn the bike. This increases loads on the tires. Now, we don't need to draw pictures or go drive on a bike to prove my point. Just get up and go out in the front yard and start running aroound in circles. The faster and tighter you make the circle the more you lean, the more force you push into you legs to turn and when that magic point happens that you are pushing out more then down, you fall down. The lower the center of gravity the flatter the thrust line. the flatter the thrust line the less weight put to the ground the easier it is to slip. I can't make this any easier. If this is still cloudy to you. I'm sorry.
Now, I can tell someone is going to pipe up and say you want a low center of gravity in a car. Yes, you do. Because as you corner a car the center of gravity is trying to raise. That pushes down harder on the outside tires. If center of gravity gets to high yuo roll.
Also, every tire is different in how mush cornering force it will hold. Some will break free before others. Leaves and pebbles do not help grip at all.
Gentlemen you have demonstrated your understanding of physics well,but what happened has a simple explanation. The rider failed to properly manage the dynamic mass of the vehicle:)
if this is the right way to turn a motorcycle then why do i not see the road racers hanging way off the bike like this, they do drag their knees as we all know but they keep their body as close to the center of gravity as possible. when they go knee down it is due to bike lean angle not hanging off the bike
Martvol, I guess this is why they make the joke about arguing on the internet...but I'm a glutton for punishment.
The question is not the total resultant force on the tires but the weight on the tires and it's effect on traction. The resultant force which is more or less in line with the angle of the bike's lean is a combination of gravity and cornering force. The faster you corner the more force is created parallel to the road and the flatter the combined result of gravity and that cornering force is. The amount of traction available is only dependent on the weight portion of that resultant force or thrust. If you could stand up at an angle you wouldn't weigh any less would you?
The force the tire has to counter the cornering force is a friction force. Friction forces are calculated as the weight on the surface multiplied by a friction factor.
The reason you lean a bike is to use gravity to create a moment around the tire's point of contact to counter the moment created by the cornering force. The reason you hang off is to allow the bike to lean less and more effectively use its suspension and clearance. None of this effects the amount of traction. It does allow you to corner faster and hense get closer to the limits friction places on cornering but now I'm getting off topic.
The bottom line is what you appear to be saying is that leaning over makes you weigh less and that's not physically possible.
I am saying that G forces do indeed increase "weight" and making those G forces more parallel to the ground does decrease grip.
I'm refering to weight as the downward force perpendicular to the road. Assuming a flat road G forces(cornering forces) that act parallel to the road can't affect weight(force into the road). In a superelevated curve(where the road slopes in down toward the inside of the curve) you can increase the force into the road in a turn which increases traction. The opposite happens in an off camber turn decreasing traction. On a flat road the G-force from cornering acts in the friction direction parallel to the surface and hence doesn't affect the force in line with the road no matter how far you are leaned over.
Whatever.
Hey harleyrider, what the hell does this guy have to do with the other rider you brought up?
Did the other guy crash? Nope. Cuz the 2 have Nada to do with each other.
Looking at the guy trying wayyy to hard to hang-off shows some serious inexperience/lack of riding knowledge.
Killboy said he ran wide at the exit. Most riders who think they can't make the turn and run wide could actually make it if they didn't Panic and Freak-Out!
Ya gotta trust your rubba and lean that fucker over like no tomorrow and chances are you will make it.
If not, you were baggin' it anyway.
Mike, If I had actually read K.B.'s description in the previous photo I wouldn't have made myself look like a "photo squid" :-)
But when Weebles wobble, why don't they fall down?
Round Bottoms
Overall force would be the same; the size of the contact patch of the tire changes with lean angle.
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