David,
You did not state what information you were looking for so I will try to include what I can in this message.
Process the scene first as there may be evidence critical to your case that may be short-lived.   As with all accidents, if you are looking for a speed analysis,  start at the final resting point and work your way backwards.  I don't know the exact details of the crash or how far down the motorcycle fell into the ditch or if the bike went airborne into the ditch.  If airbourne, you can start off with a fall or vault formula.  This will give you the speed of the bike at that point in the crash.  Then you can use a slide formula that used a beginning and end velocity to determine the speed at the beginning of the slide.  Look for tiremarks.  This can help determine how hte bike came down.  If the driver locked up the front brakes, the bike will go down.  You can look at the bikes front wheel and look for "speckling" on the tire.  Speckling shows signs of wheel lock-up or skidding.  Try to detrmine the following locations: where the bike went out of control, where it went down, where the driver lost his arm, where impact with the Jeep was, first impact with the barrier and where final rest was.  Pavement or ground markings should help determine this information.  I even have gone so far as to bring the motorcycle back to the scene if possible and lay it on the gorund wher the markings are to determine the position of the bike at each location.   If you do this, complete your damage analysis of the bike first and take photos of it before you bring it back to the scene.  When you examine the bike, take measurements just as you would a car.  Measure the rake, wheelbase, height of the seat, handlebar location, etc.  You can probably find a chart for this on Google.  If not, give me your fax and I will send you one.   Make sure you check the tires and their condition and if they are inflated or not.  If not, you need to determine if they were flat before or after the crash.  You can do this by looking at the tire marks, if any and look for overdeflective tire marks.  They have the same characteristics of a car but narrower.  And always check the experience of the driver.  See if he just started to ride or has been doing it for some time.  
There is alot of info here and I hope it helps.  If you have a specific question, let me know.  My e-mail is omegaaccidentrecon@yahoo.com.  
Craig  

Hi David,
Just checking to see how the investigation is going. 
Craig

David,
I did not receive your e-mail.  Please try again
omegaaccidentrecon@yahoo.com
Thanks
Craig

David,
For whatever reason, I'm not getting your e-mail.  You can just use this forum to contact me.
Thanks
Craig

Hi david,
I'm not sure excactly what you mean by "entangled in the barrier" so I can't be of much help with its CoF.  As for the tank slap, There are three types of "wobble".  The first is a Flutter. or a low speed wobble.  This is a low speed front wheel movement very specific to certain motorcycles and easily induced by such factors as road bumps, ruts, pavement seams, or the motorcycle itself.  Altering a bikes design can also add to this problem.  This is, as it's called, a flutter type movement easily controlled with a firm grip on the handlebars.  A rider should not touch the brakes or throttle until the flutter stops.  It is the same type of movement as a caster under a shopping cart exhibits when pushed along and can easily be stopped by placing a finger on each side of the fluttering caster, and it would stop fluttering.  Thus, your hands on each handle grip controls this problem with ease. 
Weave is a high speed wander which commences with a rear oscillation.  The wander is severe and eventuallt the whole machine weaves in a snakelike and most alarming manner.  Weaves usually occur at speeds in excess of 60 MPH and is likely to occur on curves when the bike is leaning and under stress.  The cure is simple, do not change speeds be accelerating or braking.  Just lay your head and upper torso on the tank and it will disappear.  Then slow down gradually and locate the problem.
High Speed Wobble is the result of an uncorrected weave where the rear end oscillation has passed through the frame and is transmitted to the front forks.  This is what is referred to a "tank slapper".  and end in a crash in just a few seconds.  The wobble is extrememt violent and occurs rapidly.  Lighter riders seem to be more prone while heavier riders or riders with passengers seldom experience this.  Handlebar mounted fairings or windshield can contribute to this as wel as a travel trunk mounted high and mostly to the rear of the tire. 
An experienced rider can solve these problems and not crash, as long as you knowe how to solve these problems while riding.  As I said, look into the experience of the rider and his weight. Do an examination of the motorcycle and see if any alterations, such as the length of the forks, the rake or the handlebars have been altered.  You can get the original specs of the mtorcycle on Google.  Just type in the motorcycle brand and search for what you need.
As for the speed, start with the speed you obtained in the fall.  Use the formula, Vi= square root of Ve squared - 2ad.  Ve is the fall speed you obtained, a = 32.2 x your drag factor, and d is your slide distance.  It looks like you are using metric so you would have to locate the alternate formula for this.  A motocycle sliding on its side on asphalt has an average drag factor 
of .80.  Also, make sure the motorcycle tires are mounted properly and are the right size.  A motorcycle tire is manufactured differently than a car tire.  It is one long tire secured at one point with adhesive instead of being one piece of rubber.  here should be an arrow on the tires sidewall indication which way the tire should rotate on the wheel.  If it is mounted incorrectly, it will fail.  
Also another thing to touch on, I the rider was ejected from the bike, you vcan use a vault equation for the intitial speed using the vault of the driver.  Your angle of take off should be the angle of the gas tank if he went over the handlebars.  This can be determined by examing the gas tank and see of there are dents on either side caused by the riders knees squeezing on the tank prior to take off.
Hope this helps.  
Craig       

I've seen broken wrists from tank slap, so unless they grip hard the option of knees damaging the fuel tank seem viable. Not quite so sue that gripping knees wold damage the tank, but then again, that is why we like to examine the vehicle involved to see what may be possible.

David, Jonathan, Blue B.
OK.  Looks like I've got some explaining to do so I'll do it one at a time.
Jonathan, The dents left on either side of the fuel tank of the motorcycle are not very deep so it's not like it's crushing the tank completely.  These dents are normally caused when the rider forsees the fact he/she is probably going to get thrown from the bike and uses whatever means they have to prevent this.  The person will usually have a "death grip" on whatever they can grab on to.  The last motorcycle crash I had, there were two small indentations on either side of the tank with the imprint of the person's denim jeans left.  There were also blue marks from the person's jeans on the indentations also.  This was caused by the person squeezing his knees against the tank in an effort to keep from being thrown from the motorcycle.  Hard to believe unless you see it for yourself.  I can dig up the pictures and send them to you if you want.  It is pretty unbelieveable.  As for it occurring all the time, probably not.  But it is a good indication, if they are there, of how the rider was ejected off the bike.

David, Now it makes more sense.  You actually have two methods of obtaining a speed.  Use a vault for the rider from the point he was thrown to the point of first contact with the ground.  Do not worry about any tumbling after the intital impact.  Look for the first impact with the ground.  This is your distance.  If you cannot determine the angle of take-off, use 45 degrees for a minimum speed.  This will give you the initial speed of the bike.  Compare this with the other method using the fall and slide to stop.  It's difficult to say whether .2 is a good CoF because I don't exactly know the dynamics of the motorcycle on the barrier but if that is what you got, go with it.   It sounds to me as if the rider did get caught in a high speed wobble and was not experience enough to know how to get out of it without crashing.  If he did in fact hit his front brakes only, the likelyhood of the bike going down because of this is very high.  Like I stated before,  if the front wheel locks up, the bike is going down, no ifs, ands or buts.  Also, just like a car, if the front wheel is not rotating, he cannot steer and the bike will go straight until it goes down.
Hoipe i'm being more of a help than a hinderence to you.  Sometimes I know what I want to say but it comes out wrong. 
Craig

-- Edited by omegacrash at 16:55, 2008-09-28

David, as I said to you in the e-mails we've exchanged on this topic, no one can blindly say if .2 is a reasonable CoF. You have persisted in not providing the information I mentioned to you would be necessary to come up with some reasonable CoF.

That hasn't changed. You are free, of course, to ask as many people as you'd like, but the answer is going to remain the same each time: without more information, we can't say.

I would love to see those pictures, Craig. ^_^

-- Edited by ashman165 at 17:45, 2008-09-28

David,
Never hesitate to ask for help.  I, for one, enjoy trying to figure this stuff out.  I am always ready to assist.  Keep up the good work
Craig

david wrote:

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for a projectile equation i dont know the landing point only the point of rest!!

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Knowing the point of rest would be the longest projectile distance, so even if you chose to use that, you would be looking at a 'max' speed. 
If you have an indicative speed for the vehicle from another means, you could work out the trajectory and see where that might be compared to the point of rest.   You may be able to do some assumptions ..... projectile to rest is over estimate because, ... point of rest is an underestimate because the likely projectile at the indictaive speed would be further etc.
For an indicative speed, you must have some ideas as to how the average vehicle uses that road, any comments by witnesses or other sources.  You can only develop from what you have.  Some of the results will simple be so assumptive as to have no value, but some may actualy be of use.  Until you explore them you will never know.

Ok, Lets imagine the projectile results in an initial speed of 60mph.

Knowing that most vehicles could or couldn;t negotiate the road at thse speeds helps assess whether the incident tends to be more speed related rather than another ( rider or 3rd party) influence.
Where our prrojectile speed is 60mph but road layout suggests that is not achievable, then the projectile calc may be noted as an over estimation, likewise if our projectile speed was say 40mph, but the majority of vehicles travel at 60mph and the rder is beleived to have been going faster than the average, then the projectile calc would be an underestimation.
I was not suggesting that both results would be the answer, but options to consider. Itwould be an error to simply to follow the projectile option without trying to support it from other means.
depending on witness info, if comments were ' it was being ridden at same speed as everyone else' or ' much faster/slower than the other traffic' that can be a powerful indicator so it is appropriate to conider what the other motorist was or may have been doing.
example: heav snow most motorists doing 15-20mph yet our subject is doing 50+. What the average motorist was doing is a factor to consider.

I would also like to add that the speed of the roadway is not at all important in determining the speed a driver was actually going when a collision took place. Reread that carefully, people, before you start sending me hate mail. For the task of determining at what speed some driver was driving, the speed limit of the roadway is of no importance. Nor is it relevant what speed other drivers were going, unless - of course, one of these other drivers is also in the crash itself. Other drivers, uninvolved ones, can be going 0 miles per hour, or a million miles per hour. The speed limit can be five or hundred miles per hour. Neither is relevant to determining the speed a person is actually going.

Don't disagree in terms on simply doing the calcs, and in this scenario we are using estimates etc.  The reason the road, other veh speed etc is something to be considered and taken account of , is that if we relied ONLY on the calcs and ignored the other info, we wouldn't be aware of whether the estimates were valid or not. 

Calculating a vehicles speed from an incident is just one part of the task.
Ok so you calc the veh speed at 5mph. On its own, doing that calc is wholly unrelated to the speed that other vehicles do or what the posted limit may be.
However we have calculated a speed for a purpose and having got the answer we then have to do something with it. Even if we say 'vehicle was doing 5mph, the other cars could do 60mph.' At teh very least the relationship between the two comments allows us to make comments. For example one could explain that the loss of control was not due to excess peed but may be driver behavour/road codition etc.
Simply saying 'I have calculated the vehicle speed at 5mph' and stopping has very little if any value.