How To Handle A Fall (Assuming It's Inevitable) By: James R. Davis

Of all the Tips I have posted here, this one is clearly the least credible in the sense that I have no experience in the matter, nor can I imagine a way to practice that makes any sense to me (nor would I want to.)

Still, I will post the thoughts in the hope that the reader will not take them as advice, but purely my opinions on the matter. Further, I suspect that in real life one does not have time to do anything deliberate until after the first impact, and then there may be no decisions possible. On the other hand, since I have personally witnessed a deliberate and life-saving maneuver by a woman who had just suffered a highside accident, I know that at least some people retain enough presence of mind in an accident that the following couple of ideas just might help.

• The objective should always be NOT to fall - even if the bike is going down. That is why I teach my friends how to dismount their bikes (at slow speeds) if it is dumping, or to stay with it until after first impact at higher speeds, if possible.
• DO NOT TRY TO BREAK YOUR FALL WITH YOUR HANDS!!! In other words, try to impact with as much of your body at the same time as possible.
• If you are doing a lowside the bike is ahead of you and you want it to stay that way. Since the coefficient of friction between you and the ground/asphalt is higher than of a metal motorcycle, you want to get as much of your body on the ground at the same time as you can to slow you as quickly as possible so the bike will slide away from you. In other words, arms over head, feet first, butt down. Stay LOOSE (relaxed, in as large a configuration as possible.) LET GO OF THE MOTORCYCLE AS SOON AS POSSIBLE!!!
• If you are doing a highside you will be in front of the bike when you hit the ground. You want to move as fast as possible - in the same direction you were going and for as long as you can - in order to try to avoid getting crushed. In other words, you want to 'tuck' and roll as soon as you can after you hit the ground. Stay TIGHT (in as small a configuration as possible.)

Before you try to get up after taking a spill you must be sure that you have come to a stop first! Wait a couple of seconds until you are sure.

I don't think most people will have time to do anything deliberate at all by way of falling. But perhaps I'm wrong and the above thoughts can in some way be of assistance.
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Following the posting of this Tip I received many e-mail messages which argued that a person simply does not have time to do anything that could affect the outcome of a fall. I responded with the following:

quote:

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My comments had very little to do with how you hit the ground following a 'get off' as I don't think there is sufficient time to do anything very deliberate until after the first impact, and then there may be no decisions possible. Rather, I was trying to suggest that as you are coming to rest (assuming you can function at all) then you should try to END UP either loose (as much body contact as possible with the ground) or tight (as little body contact as possible with the ground - tuck and roll posture) depending on if you went down on the low side or the highside.

Despite the fact that I don't think most people would have either the time nor the presence of mind to do much 'thinking' during a 'get off', some do. I have personally seen, for example, a woman in her late fifties do a 50 MPH highside and when she landed, because (I believe - she can't remember) she was so afraid that the bike would land on top of her, began a rapid rolling maneuver that saved her life (the motorcycle stopped 1 foot short of where she did.) I have personally witnessed this same woman (honest) respond to a huge wind gust that knocked her bike over just as we were coming to a stop at a pullout on the top of a mountain and she was thrown over her bike, this time at about 5 MPH.

During this latter 'highside' she actually did a summersault before hitting the ground - a clearly deliberate move on her part (we all watched as she tucked her head down and 'kicked' away from her bike which allowed her to land on her curved back and then she 'unwound' and stopped her roll by spreading her legs. (She had gotten away from the bike that was following her, but wanted to stop rather than keep going.) Good thing, because had she gone another five feet she would have had a SEVENTY FOOT fall off the mountain. (There was no fence or guard rail that would have stopped it.) Incidentally, Elaine saw both of these 'highsides' , too.

Anyway, I mention these events because they left a very strong impression on me that some people DO have the presence of mind to determine how to END a fall, despite how fast things are happening to them. I'm not at all sure I'm one of those people, but at least I have thought about it and know that if I'm in front of my motorcycle I want to keep moving until I can't move any more - and I want as small an exposed profile as possible, just in case that bike catches up with me.

As to the lowside concept of trying to end up on your back, arms over your head, feet first - this was originally told to me by a motorcycle 'stunt man' in LA a couple of decades ago about how he tries to stop after a dismount. (Not that any of us are into that sort of thing, of course. )

Hydroplaning Issues What is it? What to do about it? Are they making new tires less safe? By: James R. Davis

 

Hydroplaning is the result of your tires moving FAST across a wet surface - so fast that they do not have sufficient time to channel that moisture away from the center of the tire. The result is that the tire is lifted by the water away from the road and all traction is thus lost.

Of course the word 'fast' is a relative term. Tread design, tread depth, weight of motorcycle, tire pressure, depth of water and even the consistency of that water - (whether it is highly aerated or not, for example) - all play a part in determining at what speed the tire will begin to hydroplane. It is a pretty safe bet to assume that any speed in excess of 60 MPH is fast enough to support hydroplaning regardless of the other variables. This is not to say that at 55 MPH you are safe, however. (A formula that comes close to predicting the speed at which you will hydroplane, assuming at least .2" of water on the ground, is: 10.27 * Sqrt(tire pressure) which shows that if your tires hold 35 psi, hydroplaning can be expected at 60.76 MPH, while tires with 41 psi of air in them should expect hydroplaning at about 65.75 MPH. 

Another formula that is somewhat more accurate, though much harder to calculate, is: 7.95 * Sqrt(tire pressure * contact patch width / contact patch length). This formula shows that the wider the contact patch is relative to its length, the higher the speed required to support hydroplaning. I bring this to your attention because it is contrary to my understanding that a wider tire is more susceptible to hydroplaning than is a narrower tire, yet this particular formula seems to yield a closer approximation of the threshold hydroplaning speed. In other words, I cannot explain why the formula seems to work.

In any event, there are two absolutely essential NO-NO's to remember should you experience the beginning of hydroplaning:

• Do NOT apply your brakes
• Do NOT try to steer in any direction but straight ahead

Though I am not formally trained in the matter I would suggest that the only thing you can possibly do to help the situation is to feather your clutch to moderate your speed without the possibility of drive train 'snap' that would result from an abrupt change of the accelerator.

Hope there is an idea in there that you can work with. Frankly, I think if you start to hydroplane the odds are that you are going to go down unless you keep the front wheel pointed absolutely dead ahead and it is of the briefest of durations.

While on this subject I would like to make another observation about our tires. If you look at the stock front tire on all new GoldWings you will see a Dunlop K177.



If you look at the tire tread pattern you will also see that the grooves are cut in such a way as to tend to channel water away from the center of the tire if it is rotating in accord with the arrow stamped on the side of the tire. This seems to be consistent with what the Dunlop factory rep advised in his latest message to me on the subject.


However, if you look at the front tire tread pattern of the new Dunlop Elite II's (K491) they are aligned in exactly the opposite way. That is, they tend to channel water towards the center of the tire. This CANNOT be the most effective way to diminish the odds of hydroplaning! Either the K177 or the K491 is safer on wet streets based on those tread patterns. (I believe that most new street bikes (other than Honda) come with tires treaded like the K491's.)

If anyone knows why I sure would like to hear about it. Thanks.

I, of course, tried to find out the answer for myself. I wrote to the company that manufactures these tires and in my letter I explained my concerns, just as I did above.

Following is the terse response I received from the Dunlop Tire Corporation to those concerns. I think you can draw a few conclusions from this 'hedge" - at least one of which is that hydroplaning and braking compete with each other from a tread design point of view. It might also be concluded that if you start using these newer designs you should lower your speeds in the future when the roads are wet, below what used to work just fine for you (I will!).

quote:

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Our development and testing during the design of the Elite II front tire determined optimum overall performance was achieved with this pattern which includes wet traction and braking.

Dunlop Tire Corporation

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(This response was signed by a person named Tom Daley.)

Mind you that I am not of the opinion that Dunlop has made a mistake with this design! In fact, I think braking performance is FAR MORE IMPORTANT than hydroplaning resistance. This is particularly true since we can usually choose how fast we drive on wet streets but often cannot choose when it is necessary to stop quickly. I would have liked a little more candor from them on the issue, however.

For example, (because it is left to me to interpret their response), I do not know if they were actually saying that they had determined that the old design (such as IS being shipped on the front tires of new Wings) is better or not than the K491 design from an hydroplaning point of view.

Windscreens Bigger May Not Be Better At All By: James R. Davis

There has been a trend over the past few years of ever bigger windscreens showing up on our bikes. You cannot attend a major rally without seeing at least one vendor of these 'super-duper', 'larger-than-life', 'aerodynamic', 'custom-made', 'co-rider-friendly' pieces of plastic.

I like having a good windscreen in front of me. I like cutting most of the wind that buffets me during a long ride. I like having the bugs hit something other than my teeth. I like rain drops splashing on the plastic and then sliding up and over my head.

But I do not like their cost in terms of gasoline mileage or top-end speed. I do not like banging my forehead (excuse me - my helmet) on the windscreen when I mount my motorcycle. I dislike greatly not being able to look OVER my windscreen when things around me get dicey or visibility gets poor. I dislike reports of melted dashboards from leaving a bike in the sun at exactly the wrong time of day and pointed at the wrong angle relative to the sun.

As to 'aerodynamic', says who? Wind resistance is not just the angle at which you hit the wind. There is as much resistance caused by the vacuum behind your windscreen than from the wind hitting it in the front. The greater the 'apparent' surface area your windscreen has (the height times the width as seen from the front), the greater its resistance is, in one form or the other.

As to 'co-rider-friendly', what about 'rider-friendly' first? Have you ever driven at night and had difficulty seeing through your windscreen because your dash lights are all being reflected back at you from your new 'super-duper-swept-back' windscreen MIRROR? And should you get into an accident and find your head forced down by that windscreen that is levered over your head, what part of that new windscreen do you think your co-rider is going to hit first? (Notice how close the edge now is to her eyes?)

Like having that windscreen sweep around your grips? I guess you never did like the convenience of hanging your helmet using its D-ring and the peg that was designed to fit it?

Well, the larger screens look good. They are just right for some people. But do yourself a favor and take a ride behind one of them for a few hundred miles, day and night, before you decide to give up what you know works for one of these 'custom-made' monsters. The old one you already have just might be better than you think.