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Old 02-26-2014, 10:10 AM   #61
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Old 02-26-2014, 06:45 PM   #62
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No point in arguing if you did not know the guy really, as it's an argument made many time before, just let those that know them grief and so forth. Hopefully, other's will see from this and wear their gear while out and about on two wheels cause you can't trust other drivers, and leave those keys in the pocket and call a cab if they decide to roll in a cage after some drinks, or anything else that effects your attention and impares you for that matter.
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Old 02-26-2014, 09:05 PM   #63
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Some people just flat out fail at physics. Its not a 1000# bike at 40. Its a wrecking ball. Get it?
Correct.

He rode a Harley Ultra Classic. That bike weighs about 800 lbs dry, 850 wet. He was not a little guy, about 250 lbs. She is smaller, probably 130. Total weight about 1250, including what is in the bags.

The formula for kinetic energy (ft/lbs) is -

Ek = (W * Sē)/30

At 40 MPH that is over 66,000 ft/lbs of energy.

To put that amount of force into a scenario someone could understand visually, if that amount of energy were directed up underneath that same car that was in the collision, it would knock that 4000 lb car 16 feet straight up into the air.

Yes, it will spin that car if the force is directed behind the center of gravity. Believe it.

Center of gravity on most cars is roughly about where the stick shift is, or ashtray. If they punched into the rear passenger door or B-pillar with the car slightly angled toward the bike, as I understand the collision happened, then it was certainly behind the center of gravity, and science would tend to agree with the witness statements of 40 MPH.
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Old 02-26-2014, 09:20 PM   #64
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Oh, and as I understand what the emergency crews were working on, it's not likely that any amount of gear would have saved him. It was blunt force trauma to the chest, internal chest cavity hemorrhage. That is caused by delta-V/time, which gear does not alter. The only thing that alters delta-V/time is something that stretches the time of the collision impact, like vehicle crumple zones and airbags.

Look at it like this... You slow from 500 mph to a stop. Do you die?

It depends on whether you are landing in an airplane or hitting a wall. The difference between 1 minute to slow down and a tenth of a second to slow down. With one, you get your luggage out of the overhead compartment. With the other, they paint over your stain.

Same thing slowing from 40 MPH to zero. If you do it in a tenth of a second, the gear probably won't help you. Your guts still explode. If you can do it in two tenths of a second, the collision isn't as bad. If you can stretch the time out to a half second, the collision is downright survivable.

Please don't get me wrong, I approve of wearing gear and improving your odds while riding. It's not why Tweedy died.
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Old 02-26-2014, 09:59 PM   #65
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Quote:
Originally Posted by LCLF Brain View Post

To put that amount of force into a scenario someone could understand visually, if that amount of energy were directed up underneath that same car that was in the collision, it would knock that 4000 lb car 16 feet straight up into the air.
The number is still worthless because it assumes an elastic collision which crumpling sheet metal, tires, etc can never have. It also assumes he hit the car at 40, not braking or avoiding.

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Originally Posted by LCLF Brain View Post
That is caused by delta-V/time, which gear does not alter. The only thing that alters delta-V/time is something that stretches the time of the collision impact, like vehicle crumple zones and airbags.
Gear DOES alter this, a helmet doesn't just prevent skull fractures, the foam collapses. Same with leather and armor. It also prevents all of the energy being directed to small areas of your body which can lead to broken ribs etc.

Quote:
Originally Posted by LCLF Brain View Post
Please don't get me wrong, I approve of wearing gear and improving your odds while riding. It's not why Tweedy died.
We don't have the information to make this judgement at all. Unlike hitting a brick wall, cars dent and move (and spin 180 degrees). This drains the energy you talked about and increases your chances of living. Gears also helps a great deal and not just from skull fractures. I'm not trying to be argumentative, or disrespect the rider at all. But gear is much more useful than you say, and this accident was not as unsurvivable as you say.

I'm not saying gear is a cloak of armor. Just this weekend in Bay City I saw a guy riding past with his helmet hanging off his bike and he was wearing a tshirt. When I caught up to him he was pinned between two cars when he attempted to make a left hand turn.

Last edited by MoreyFan; 02-26-2014 at 10:03 PM.
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Old 02-26-2014, 10:48 PM   #66
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My brother was killed in a crash very similar. A car pulled in front of him, he was going 45mph and had full gear. Blunt force trauma with that much of an impulse tears your aorta and lots of other vital structures apart.
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Old 02-27-2014, 11:48 AM   #67
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The number is still worthless because it assumes an elastic collision which crumpling sheet metal, tires, etc can never have. It also assumes he hit the car at 40, not braking or avoiding.



Gear DOES alter this, a helmet doesn't just prevent skull fractures, the foam collapses. Same with leather and armor. It also prevents all of the energy being directed to small areas of your body which can lead to broken ribs etc.



We don't have the information to make this judgement at all. Unlike hitting a brick wall, cars dent and move (and spin 180 degrees). This drains the energy you talked about and increases your chances of living. Gears also helps a great deal and not just from skull fractures. I'm not trying to be argumentative, or disrespect the rider at all. But gear is much more useful than you say, and this accident was not as unsurvivable as you say.

I'm not saying gear is a cloak of armor. Just this weekend in Bay City I saw a guy riding past with his helmet hanging off his bike and he was wearing a tshirt. When I caught up to him he was pinned between two cars when he attempted to make a left hand turn.

Where myths, anecdotes and layman's observations trump a collision reconstructionist and accident instructor, who has investigated somewhere around 3000 accidents.

You win, dude.
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Old 02-27-2014, 11:49 AM   #68
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Quote:
Originally Posted by LCLF Brain View Post
Where myths, anecdotes and layman's observations trump a collision reconstructionist and accident instructor, who has investigated somewhere around 3000 accidents.

You win, dude.
You are a "collision reconstructionist"? Surely you know these collisions are not elastic and your numbers are worthless then?

I didn't posy any myths. The anecdote was about how gear can't always saves you (which served to concede some of your points), and I'm not sure where you saw laymans observations. You went to a physics argument.

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Old 02-27-2014, 11:55 AM   #69
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Originally Posted by Salty View Post
My brother was killed in a crash very similar. A car pulled in front of him, he was going 45mph and had full gear. Blunt force trauma with that much of an impulse tears your aorta and lots of other vital structures apart.
That's exactly right. The way it works is that your organs carry blood and fluids, and they reach the end of your chest cavity during impact. If that blood and fluid has more kinetic energy than the organ wall can contain during that shock, during that delta-V/time, then the organ ruptures - it's simply called a hemorrhage.

Gear, leather, body armor, it can help disperse the energy over a wider area to prevent a break, like ribs or something, from direct force. It takes a 1 inch strike and turns it into a 6 inch strike, hoping the skull or bone structure can withstand it without breaking, because obviously breaking is bad.

But gear doesn't prevent the hemorrhage type injury that results from the body fluid breaking through the organ wall. That is strictly caused by delta-V, which is change in velocity. And it is ONLY prevented by increasing the time in the collision.

It's why cars are now designed to mash up in a collision. It's why crash barrels are put at feeder off ramps. Increasing the collision time by a couple tenths of a second help greatly.

The foam in your helmet doesn't make any difference in that time. It's just an inch worth of travel, which crushes in a hundreth of a second, or faster. It simply helps distribute the energy throughout the entire skull area. Cradles it to move the shock to a 6" area.
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Old 02-27-2014, 11:57 AM   #70
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Quote:
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You are a "collision reconstructionist"? Surely you know these collisions are not elastic and your numbers are worthless then?

I didn't posy any myths. The anecdote was about how gear can't always saves you (which served to concede some of your points), and I'm not sure where you saw laymans observations. You went to a physics argument.
I already acquiesced to your expertise.
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Old 02-27-2014, 11:58 AM   #71
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Quote:
Originally Posted by LCLF Brain View Post

The foam in your helmet doesn't make any difference in that time. It's just an inch worth of travel, which crushes in a hundreth of a second, or faster. It simply helps distribute the energy throughout the entire skull area. Cradles it to move the shock to a 6" area.
It takes energy to crush the foam. Crushing the foam takes work. Work performed eats kinetic energy. This is the entire use of the foam and why you need a new helmet every 5 years.
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Old 02-27-2014, 11:58 AM   #72
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I already acquiesced to your expertise.
Thanks, because your physics is lacking.
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Old 02-27-2014, 01:46 PM   #73
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Old 02-27-2014, 02:05 PM   #74
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Quote:
Originally Posted by LCLF Brain View Post
That's exactly right. The way it works is that your organs carry blood and fluids, and they reach the end of your chest cavity during impact. If that blood and fluid has more kinetic energy than the organ wall can contain during that shock, during that delta-V/time, then the organ ruptures - it's simply called a hemorrhage.

Gear, leather, body armor, it can help disperse the energy over a wider area to prevent a break, like ribs or something, from direct force. It takes a 1 inch strike and turns it into a 6 inch strike, hoping the skull or bone structure can withstand it without breaking, because obviously breaking is bad.

But gear doesn't prevent the hemorrhage type injury that results from the body fluid breaking through the organ wall. That is strictly caused by delta-V, which is change in velocity. And it is ONLY prevented by increasing the time in the collision.

It's why cars are now designed to mash up in a collision. It's why crash barrels are put at feeder off ramps. Increasing the collision time by a couple tenths of a second help greatly.

The foam in your helmet doesn't make any difference in that time. It's just an inch worth of travel, which crushes in a hundreth of a second, or faster. It simply helps distribute the energy throughout the entire skull area. Cradles it to move the shock to a 6" area.
I remember in my disaster relief training, we were taught there are three impacts in a vehicle accident: the impact of your vehicle hitting whatever other object is involved, the impact of your body hitting whatever brings it to rest inside your vehicle (seatbelt and/or airbag, or else the steering wheel or windshield) and lastly the impact of your internal organs hitting the backside of your skeleton (be it your skull or ribcage). The last one is the one that kills you.
Having dealt with accident reconstruction specialists in the past, I gotta side with LCLF on this one. FTP brothah, I got your back.
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Old 02-27-2014, 02:16 PM   #75
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I remember in my disaster relief training, we were taught there are three impacts in a vehicle accident: the impact of your vehicle hitting whatever other object is involved, the impact of your body hitting whatever brings it to rest inside your vehicle (seatbelt and/or airbag, or else the steering wheel or windshield) and lastly the impact of your internal organs hitting the backside of your skeleton (be it your skull or ribcage). The last one is the one that kills you.
Having dealt with accident reconstruction specialists in the past, I gotta side with LCLF on this one. FTP brothah, I got your back.
Energy is lost in each impact you described. So the seat belt and airbag is the same part in your example as the gear on a motorcycle rider. When the foam and leather are crushed the energy in the next impact is lower because some of it has been used to crush foam.

The more energy you can put into crumple zones and airbags, the less that impacts your body. LCLF Brain is saying gear does nothing for this which he contradicts in his own post because he says "which crushes in a hundreth of a second". Airbag deployment is in milliseconds. If it requires energy to crush foam, it does work on that foam, so the kinetic energy transferred to your body is less.
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Old 02-27-2014, 02:31 PM   #76
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Jesus. Dude, we're all duly impressed by your grasp of physics, leave it be.
The thread is an RIP thread, not a platform for you to practice on your Masters thesis.
A good man has died due to the careless actions of a young girl.
His wife is battling for her life from her injuries.

Godspeed to Tweedy, prayers for his wife's recovery and may have mercy on the girl who caused it.
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Old 02-27-2014, 02:36 PM   #77
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Energy is lost in each impact you described. So the seat belt and airbag is the same part in your example as the gear on a motorcycle rider. When the foam and leather are crushed the energy in the next impact is lower because some of it has been used to crush foam.

The more energy you can put into crumple zones and airbags, the less that impacts your body. LCLF Brain is saying gear does nothing for this which he contradicts in his own post because he says "which crushes in a hundreth of a second". Airbag deployment is in milliseconds. If it requires energy to crush foam, it does work on that foam, so the kinetic energy transferred to your body is less.
I know what he is saying. I underlined the last part of your statement for emphasis, because it is critical to what others are saying. The energy transfer is less, but it is not eliminated. What is being said is that in cases similar to this, the impact is so great as to overwhelm the effectiveness of the gear i.e. too much energy is being transferred to the riders body. Same thing happens with a significant enough hit in a car, sometimes all the crumple zones and side impact airbags just aren't enough. There are few on here that would argue that wearing gear is a waste of time.
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Old 02-27-2014, 02:38 PM   #78
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I know what he is saying. I underlined the last part of your statement for emphasis, because it is critical to what others are saying. The energy transfer is less, but it is not eliminated. What is being said is that in cases similar to this, the impact is so great as to overwhelm the effectiveness of the gear i.e. too much energy is being transferred to the riders body. Same thing happens with a significant enough hit in a car, sometimes all the crumple zones and side impact airbags just aren't enough. There are few on here that would argue that wearing gear is a waste of time.
We agree with each other. What LCLF Brain posted doesn't agree with our consensus.
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Old 02-27-2014, 03:02 PM   #79
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Quote:
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We agree with each other. What LCLF Brain posted doesn't agree with our consensus.
Uh, yeah he does...

Quote:
Originally Posted by LCLF Brain View Post
That's exactly right. The way it works is that your organs carry blood and fluids, and they reach the end of your chest cavity during impact. If that blood and fluid has more kinetic energy than the organ wall can contain during that shock, during that delta-V/time, then the organ ruptures - it's simply called a hemorrhage.

Gear, leather, body armor, it can help disperse the energy over a wider area to prevent a break, like ribs or something, from direct force. It takes a 1 inch strike and turns it into a 6 inch strike, hoping the skull or bone structure can withstand it without breaking, because obviously breaking is bad.

But gear doesn't prevent the hemorrhage type injury that results from the body fluid breaking through the organ wall. That is strictly caused by delta-V, which is change in velocity. And it is ONLY prevented by increasing the time in the collision.

It's why cars are now designed to mash up in a collision. It's why crash barrels are put at feeder off ramps. Increasing the collision time by a couple tenths of a second help greatly.

The foam in your helmet doesn't make any difference in that time. It's just an inch worth of travel, which crushes in a hundreth of a second, or faster. It simply helps distribute the energy throughout the entire skull area. Cradles it to move the shock to a 6" area.
If you are making the point that the foam inside the helmet does slow your skull down, well yes technically that is true but the effect of that is minimal in that form. Its like saying your front forks would collapse like a crumple zone. From a purely engineering perspective, yeah, but there is little resistance to impact there compared to what the crumple zone in a car will provide.
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Old 02-27-2014, 03:24 PM   #80
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Uh, yeah he does...If you are making the point that the foam inside the helmet does slow your skull down, well yes technically that is true but the effect of that is minimal in that form. Its like saying your front forks would collapse like a crumple zone. From a purely engineering perspective, yeah, but there is little resistance to impact there compared to what the crumple zone in a car will provide.
If you are saying a helmet on a bike is less safe than a car, I agree.But then you say foam deforming (when it absorbs energy) does not make a significant difference to preventing death. This is just false. That is the entire point of the foam. Why after you fall with a helmet once, you need a new helmet. The foam has done it's job and deformed.

Then entire test for CE armor ratings has to do with how much energy the armor absorbs in a collision. http://www.satrappeguide.com/EN1621.php

Gear doesn't just stop skull fractures and road rash. Foam is a crumple zone.
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