Previous in Forum: Fill Your Car Tires With Nitrogen? Next in Forum: Starter motor for IC engine
Participant

Join Date: Aug 2008
Posts: 3

# how fast was i traveling?

08/12/2008 5:20 PM

I know there are a lot of variables to this question but I am trying to figure out how fast i was going in a recent motorcycle accident. A lady making a left out of her driveway caused me to lay the bike down and take a nice enjoyable pavement slide of aprox 81 ft. I weigh 150lbs and the bike weighs 380lbs. The downslope of the road is around 5 degrees. Any calculations or guesses would be appreciated. Thanks in advance.

Oh yeah, i slid on my right side without hitting anything or tumbling.

Interested in this topic? By joining CR4 you can "subscribe" to

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, rate them!
Guru

Join Date: May 2007
Location: Harlow England
Posts: 16510
#1

### Re: how fast was i traveling?

08/12/2008 5:36 PM

42.5 mph ... ish

__________________
health warning: These posts may contain traces of nut.
Power-User

Join Date: Aug 2007
Posts: 479
#4

### Re: how fast was i traveling?

08/12/2008 8:01 PM

Correct but pls provide answer in metric units. Tnks!

Off Topic (Score 5)
Guru

Join Date: Nov 2007
Location: Gone to Alabama with my banjo on my knee...
Posts: 5595
#46

### Re: how fast was i traveling?

08/19/2008 8:00 AM

Having provided one of the few real answers to the question as posed, it would appear from the others who did so later that your answer is, so to speak, middle of the road, and about right. Clever kitty! Want a reward?

__________________
Veni, vidi, video - I came, I saw, I got it on film.
Guru

Join Date: Jul 2007
Location: Fort Lauderdale Florida
Posts: 5708
#2

### Re: how fast was i traveling?

08/12/2008 6:05 PM

The friction of the road would need to be tested. But by using a standard figure of .02436. And by estimating the total surface area likely to be exposed at 326.58Sq in. Then estimating the bare skin surface area vs the clothing shielded area to be 50%. I have come up with the speed of too fast for conditions. Please be more careful.

__________________
Bob
Associate

Join Date: Aug 2008
Location: Oklahoma City, Oklahoma, USA
Posts: 47
#3

### Re: how fast was i traveling?

08/12/2008 6:47 PM

Not enough info. I have no way to determine the amount of drag. Or in your case skip.

__________________
What's that Lassie, Timmy's stuck in the well
Power-User

Join Date: Jun 2008
Location: Near Nashville TN USA
Posts: 203
#5

### Re: how fast was i traveling?

08/13/2008 10:56 PM

For a 'reasonable rough guess', stop by the local constabulary watering hole (or donut shop) and buy them one. Then ask them to tell you what their 'rules of thumb' say.

Now you are required to report back here what you find out!

<fine print>

Mr. Phelps, if you or any of your IM staff are captured, the President will deny all knowlege of you or your assignment.

</fine print>

Anonymous Poster
#6

### Re: how fast was i traveling?

08/13/2008 10:57 PM

Darn, here I was hoping this was a speeding question.

I have known state troopers who lied about the speed they got me at, then had the balls to say "let the court sort it out", sounds like the warrior saying of "kill them all and let God sort them out." This cop did say I was ticket #18 that day, and the first 17 were with laser and mine was with laser, no it was with radar, ... this was so far west in Oregon it was almost in Idaho. The cop and a friend were ticketing everything that moved. I was in a canyon which the cop's radar was probably reading his own speed, because he sure wasn't reading mine.

I also got stopped once in Nebraska, and it was a really windy day with a bad crosswind, the trooper was sitting down in the median behind a bridge railing, by then I was using my speedometer and my GPS to set my speed, and when he came up to the window I explained to him what both were reading, he said for an instant I was going over the limit on his laser, dah, the wind was blowing and shifting the cars around as they went across the bridge, the instantaneous laser speed may be different then the GPS 1 second speed updates, thus human reaction time is not fast enough to correct or adjust speed anymore. I was driving a 4x4 Jeep which doesn't change speed quickly, unless adjusted sideways by a 40mph wind gust. This was a state trooper also.

I've also seen police use a downhill slope and a stand of trees by the Endeavor, WI exit that blocked the wind in a 100 yard long stretch right after the brridge on I-39 southbound in Marquette Co, WI watch out for the state trooper there. Cars accelerate 3-5 mph in the dead zone going downhill before cruise or driver reacts.

There is a radar training manual available on the internet produced by a retired Utah State Trooper.

They say "9 your fine, 10 your mine", mph over the limit that is.

Off Topic (Score 3)
Guru

Join Date: Sep 2007
Location: Wrong end of the yellow brick road in Oz
Posts: 930
#8

### Re: how fast was i traveling?

08/13/2008 11:30 PM

9 over the limit is much better than here in Vic Oz,

>3km over the limit and your ticketed,

Measuring devices are only accurate to the smallest division, speedo's thats about 5km/h then you have the design tolarance of a few percent, so much more than the 3km/h over limit.

The police here are mearly revenu raisers for the Government wallies

__________________
Qn, Whats the differance between a Snake and a Onion? Ans, No one cries when you chop up a Snake
Score 2 for Off Topic
Power-User

Join Date: Jun 2006
Location: Melbourne, DownUnder
Posts: 283
#12

### Re: how fast was i traveling?

08/14/2008 3:54 AM

Last time i was booked in Vic a private contractor got me at 53 KLM (50 klm zone) going to the shops and 7 minutes later the same camera got me at 54 going home. 2 demerit points and \$240. No signs. Sneeky Bastar........ds.

__________________
If you don't laugh, you cry.
Off Topic (Score 5)
Power-User

Join Date: Jan 2007
Location: The Capital City, Cow Hampshire, USA
Posts: 476
#13

### Re: how fast was i traveling?

08/14/2008 5:00 AM

Are your limits as arbitrary as here on East Coast, USA?

A personal anecdote: A road i lived near had a 100kmH limit (had been so for @ least 20yr), a drunk goes off the road, limit now 50kmH. There had been no major changes to the road before, or, since.

__________________
If you always do what you've always done, You'll always get what you've always had!
Guru

Join Date: Nov 2007
Posts: 519
#14

### Re: how fast was i traveling?

08/14/2008 6:50 AM

We use kmH in the US?

Also to Guest's comment, I wouldn't think that wind gusts would affect a radar signal enough to cause a police officer to pull you over. Of course, I don't really know how a radar gun works (yet).

Personally, I've never been pulled over and accused of speeding when I wasn't. I have heard stories about people getting pulled over and getting tickets for speeding when they say they weren't. The funny thing is that when I ride with these people that have these stories, they never use cruise control and they maintain a constant speed of anywhere from 5mph to 20mph over the speed limit.

I'm not saying that you were speeding but I just find it hard to believe these stories after witnessing the way so many people drive.

Score 1 for Off Topic
Power-User

Join Date: Jan 2007
Location: The Capital City, Cow Hampshire, USA
Posts: 476
#15

### Re: how fast was i traveling?

08/14/2008 7:13 AM

No, we do not use kmH in the US.

Just thought it courteous to keep the same u/m as the person of whom i's asking the question; should help to make the "feel" of the situation more visceral.

__________________
If you always do what you've always done, You'll always get what you've always had!
Guru

Join Date: May 2007
Location: Harlow England
Posts: 16510
#16

### Re: how fast was i traveling?

08/14/2008 7:40 AM

Wind will effect a Radar signal just as much as it effects a beam of light.

If you shine a torch (flashlight) on a windy night you will see how much the field of illumination blows about...

Del

__________________
health warning: These posts may contain traces of nut.
Off Topic (Score 5)
Guru

Join Date: Nov 2007
Location: Gone to Alabama with my banjo on my knee...
Posts: 5595
#26

### Re: how fast was i traveling?

08/14/2008 3:03 PM

I suppose that explains the twisting and flickering of the northern lights, eh? High altitude winds...

__________________
Veni, vidi, video - I came, I saw, I got it on film.
Off Topic (Score 5)
Power-User

Join Date: Jun 2006
Location: Melbourne, DownUnder
Posts: 283
#31

### Re: how fast was i traveling?

08/14/2008 8:25 PM

Funny one Del. Haven't had a good laugh for ages. What a crack up. He He.

__________________
If you don't laugh, you cry.
Off Topic (Score 5)
Guru

Join Date: Nov 2007
Location: Gone to Alabama with my banjo on my knee...
Posts: 5595
#25

### Re: how fast was i traveling?

08/14/2008 3:00 PM

Glad this is OT already...reminds me of a time when I got on Hwy 35 in a town to remain nameless in Kansas, going to the next exit ramp 1 mile down the road (but 3 miles shorter than going around). I saw a Highway Patrol car down the road a few hundred yards as I went on the entrance ramp, so was not pushing my speed, plus I only was going that one short mile, so how fast did I need to be going? The speed limit on that stretch was 55 mph, and I might have gotten close to that. Before I got to the exit ramp however, he pulled me over and wrote me a ticket for 64 mph. I went to court over that one. I won it too. Here's how:

I did a bit of research on how that particular radar gun was calibrated. They use a tuning fork (I forget the pitch) that vibrates at the equivalent of - wait for it - exactly 64 mph! I made the case that if there was anything on or about my car that was vibrating at the same pitch, it would register the same as the tuning fork. True or not, the judge bought it, which was good enough for me! So here's an add-on question - was I telling the truth, or not?

__________________
Veni, vidi, video - I came, I saw, I got it on film.
Off Topic (Score 5)
Guru

Join Date: Sep 2006
Location: Auckland, New Zealand
Posts: 8778
#7

### Re: how fast was i traveling?

08/13/2008 11:05 PM

How fast do you normally travel down that particular stretch of road?

My guess would be approximately the same speed as the motorcycle before you laid it down.

__________________
Anonymous Poster
#9

### Re: how fast was i traveling?

08/14/2008 1:05 AM

You can find out from the lady ,so simple and then multiply by 0.6 , you get the figure .

Anonymous Poster
#10

### Re: how fast was i traveling?

08/14/2008 1:11 AM

There are too many unknowns to estimate how fast you were going. The only way to come up with a reasonable estimate is to recreate the event. Take your bike down the same stretch of road at various speeds (during the same weather conditions etc. etc.), lay it down and measure how far you slide. Of course, once you replicate an enjoyable pavement slide of 81 feet, you will have to repeat it a few times to to verify the result. You will be expected to publish your results in this forum.

Participant

Join Date: Aug 2008
Posts: 3
#22

### Re: how fast was i traveling?

08/14/2008 1:04 PM

Yeah as soon as I heal up I will get right on this experiment thanks

Guru

Join Date: Sep 2007
Location: Wrong end of the yellow brick road in Oz
Posts: 930
#11

### Re: how fast was i traveling?

08/14/2008 1:14 AM

Check the skid marks

and the ones on the Road

__________________
Qn, Whats the differance between a Snake and a Onion? Ans, No one cries when you chop up a Snake
Anonymous Poster
#17

### Re: how fast was i traveling?

08/14/2008 8:03 AM

Dude, you're screwed. First of all you were on a bike, that makes it your fault regardless of what the actual facts are. The police and general public have been so conditioned by movies and television that bikes and everyone that rides one are Hells Angels and out to kill everyone except the young girls who they rape then kill, you will be stuck with the liability regardless. Gee! Thanks Hollywood! Pity really, I would like to buy another nice 250cc bike to commute to work and enjoy the 100 mpg again but, the public perception makes that impossible.

Score 1 for Off Topic
Guru

Join Date: May 2007
Location: Aloha or
Posts: 617
#19

### Re: how fast was i traveling?

08/14/2008 11:28 AM

Guest,

In my opinion your problem is your attitude. You have given up with out putting forth any effort. Sure there are issues with the general public's perception of motorcyclists. Your going along with it only makes it worse. You are now part of the problem. You are missing out and its your own choice.

As to the posted topic, unless we can find out some coefficient of friction numbers this is a difficult problem. Most police investigators have some standard number to use in these cases. Have you tried asking them for what they think your starting speed was?

__________________
Closed biased minds are utterly impervious to any factual evidence which contradicts their beliefs
Associate

Join Date: Apr 2008
Location: Atlanta, GA
Posts: 51
#18

### Re: how fast was i traveling?

08/14/2008 11:27 AM

My experience, I crashed with my motorcycle at 40 km/h, flew about 15 meters (45 feet), and then rolled another 10 m, according expectators. You must have been doing 60 to 70 km/h to drag that long. That is around 40 mph, just a guess from experience.

BTW, dragging in the road depends on the jacket you had, if it slides good or bad, in other falls in curves with water on the road or gravel, at 30 kmh, with leather jacket, I drag 10 meters. With maaany km/year on bikes, I had several falls, just one of them affected my health record, my neck got hurt and my elbow . The helmet and jacket saved my normal functioning, the chiropractor fixed the rest. Now old, i drive more careful and sold my bike 2 years ago.

Best bet

BE SAFE

Guru

Join Date: Oct 2006
Location: New Jersey U.S.A.
Posts: 1114
#20

### Re: how fast was i traveling?

08/14/2008 11:50 AM

Most police will use a rule of thumb considering the length of the skid. Unfortunately this is usually done for 4 wheels and the brakes locked up. There are more variables then just the road conditions. Do you have crash bars on your bike? Are they in the front and rear? What happened to the handlebars? Did they dig into the blacktop (another question) or concrete? What type of axles and were these involved in the skid? Do you have a fairing attached? How long were the wheels attempting to grab before you decided it was time to bail out? Did you stay with the bike or did you leave it to it's own demise?

Only you know whether you were going too fast, just right, or tooling along enjoying the breeze? I wish you well and hope nothing is too serious. Hope you get back on the road soon!

By the way contact Del the Cat at KrisDel and company. They may be dealing in genetics and could probably fix you up with a couple extra sets of eyes and ears! I know I always wish I had them on my commute home from the NYC area during rush hour.

__________________
The last fight was my fault. My wife asked "What's on the TV?" I said "Dust!"
Guru

Join Date: Oct 2006
Location: New Jersey U.S.A.
Posts: 1114
#21

### Re: how fast was i traveling?

08/14/2008 11:54 AM

By the way! Whenever the JERK pulls out in front of you. The last thing you wonder about is Gee! I wonder what my speed is? By that time I don't even care to look at the speedo. So I know how your feeling.

__________________
The last fight was my fault. My wife asked "What's on the TV?" I said "Dust!"
Participant

Join Date: Aug 2008
Posts: 3
#23

### Re: how fast was i traveling?

08/14/2008 1:20 PM

I appreciate your comment there charsley99. It was a gorgeous sunny Saturday afternoon coming home on my Ducati 1098S ( 525 miles btw) on a nice twisty rd, when all the sudden theres a car pulling out in front of me. As fast as I said to myself OH SH*T, I was sliding on my side, listening to my bike doing the same, and then I thought to myself, " Wow, I wonder how fast I was going?"

Guru

Join Date: Nov 2007
Location: Gone to Alabama with my banjo on my knee...
Posts: 5595
#27

### Re: how fast was i traveling?

08/14/2008 3:14 PM

Oh, yeah, I'll just BET that was your very next thought! I'm sure it would've been mine, too...NOT! Heal quickly, and put cutouts on your exhaust pipes - loud pipes save lives!

__________________
Veni, vidi, video - I came, I saw, I got it on film.
Power-User

Join Date: Jan 2007
Location: The Capital City, Cow Hampshire, USA
Posts: 476
#29

### Re: how fast was i traveling?

08/14/2008 5:44 PM

"put cutouts on your exhaust pipes - loud pipes save lives!"

Wouldn't they help a lot more if they were aimed forward? That's where the zombies that can cause you trouble come from!

__________________
If you always do what you've always done, You'll always get what you've always had!
Guru

Join Date: Nov 2007
Location: Gone to Alabama with my banjo on my knee...
Posts: 5595
#32

### Re: how fast was i traveling?

08/15/2008 10:49 AM

Well, yeah, but until you are traveling faster than the speed of sound, it shouldn't make a difference...

__________________
Veni, vidi, video - I came, I saw, I got it on film.
Power-User

Join Date: Jan 2007
Location: The Capital City, Cow Hampshire, USA
Posts: 476
#34

### Re: how fast was i traveling?

08/15/2008 6:16 PM

You don't believe in the directional nature of sound propagation??

Take a walk around any engine @ full whack, then tell me it ain't so!

__________________
If you always do what you've always done, You'll always get what you've always had!
Guru

Join Date: Nov 2007
Location: Gone to Alabama with my banjo on my knee...
Posts: 5595
#35

### Re: how fast was i traveling?

08/16/2008 5:53 AM

Concur the sound is definitely louder in the direction the exhaust pipes are pointed. However, it's not gone completely in the diametrically opposed direction. Run a Harley up to full throttle down the road, and people far ahead of you will be aware of your impending approach. By the same token, people you have left behind will be reminded you once were there. And people off to all the sides of your path will know someone on a Harley is going down that road. Sound propagates non-uniformly perhaps, but always omnidirectionally. There, enough big words in that paragraph to convince you?

__________________
Veni, vidi, video - I came, I saw, I got it on film.
Power-User

Join Date: Jan 2007
Location: The Capital City, Cow Hampshire, USA
Posts: 476
#36

### Re: how fast was i traveling?

08/16/2008 6:16 AM

Not really: I currently own (they own me?) a BSA Victor Spl., & a BMW R-26.

Have nearly had my left hand struck by a passing (on the left; USA, y'know) auto, while using it to signal a LEFT TURN, in a zone clearly marked 'not for passing' w/ our std double yellow stripes. That she pulled around me to pass has to have meant that she 'saw' me (& that she didn't know the 'old school' hand signals, or, WORSE: didn't give a \$#!+ whether she turned me into road-pizza, or not).

Your "omnidirectional" sound doesn't seem like it could arouse the attention of the 'brain dead' auto driver.

What it can do is reinforce the stereotype of bikeys as miscreants;thereby raising a degree of ire, & turning bikes INTO TARGETS. (there are lawless types on 4 wheels, too)

To all: KEEP YOUR EYES & EARS OPEN! Your safety depends on yourself.

__________________
If you always do what you've always done, You'll always get what you've always had!
Guru

Join Date: Nov 2007
Location: Gone to Alabama with my banjo on my knee...
Posts: 5595
#37

### Re: how fast was i traveling?

08/16/2008 8:43 AM

Oh, AMEN! Eyes are more important here than ears, for sure. But my theory is, the more sensory input, the better! Some people just can't seem to SEE motorcycle-sized objects. How they read stop signs shall forever remain a mystery.

When I used to teach forklift safety for operators, I heavily emphasized the use of the horn when approaching corners, side aisles, doors, and other blind spots. I'd always tell 'em if anyone complained about too much noise, ask if they'd rather you sneak up on them to run them down, or know the machine was approaching? Always got a chuckle, but I doubt any of my drivers ever forgot it. And they were a NOISY lot, too!

__________________
Veni, vidi, video - I came, I saw, I got it on film.
Guru

Join Date: Aug 2006
Location: Midwestern United States
Posts: 843
#40

### Re: how fast was i traveling?

08/18/2008 10:57 AM

"Loud Pipes Save Lives" and the ensuing debate that followed related to their pros and cons...

Those drivers that pose a danger to others (primarily motorcycles and first responders) are those that subconsciously view the confines of their automobile as the outside boundaries of their present world.

They have their windows ups, their radios on, talking on the phone, looking at maps, or are having a passionate discussion with others in the car and their only focus is on the immediate requirements of their travel : the car in front of them and the upcoming traffic light... other than that, they are oblivious to their surrounds.

Loud pipes and loud sirens wake them up... well, most of them.

Bottom line is if we all paid attention to what we were doing and were as focused as we should be... first responders would not need sirens, only lights. But that's not the case now is it?

So, as for me... sure I am a respectful rider and try to make a good impression while on my bike to further the advancement of a positive outlook on bikers... but it stops at my headlight and my pipes... my headlight is bright and my pipes are loud... if I annoy you that means I have your attention.

And there is a difference between having loud pipes an needlessly exaggerating your acceleration to show them off while in a residential neighborhood at 11pm at night.

__________________
Reuters - Investigators found that the recent thread derailment in CR4 was caused by over-weight creatures of lore and request that membership DON'T FEED THE TROLLS.
Anonymous Poster
#41

### Re: how fast was i traveling?

08/18/2008 11:09 AM

Motorcycle riding makes for a better car driver. It's all in the mind, not in the noise.

Guru

Join Date: May 2007
Location: Aloha or
Posts: 617
#42

### Re: how fast was i traveling?

08/18/2008 12:08 PM

For most new vehicles, loud pipe do not save lives. The newer cars on the market are so well sound insulated that they just don't hear outside sounds until they are right next to it, if then, especially if they play their music loud. It is a terrible mistake to assume that loud pipes will help you in traffic. You are much better off to assume that the car driver does not know you are there.

I do ride a Harley with loud pipes and have had a few close calls with drivers who just pulled into me as if I wasn't there. I turned over 170,000 miles on my way home from camping yesterday.

__________________
Closed biased minds are utterly impervious to any factual evidence which contradicts their beliefs
Guru

Join Date: Nov 2007
Location: Gone to Alabama with my banjo on my knee...
Posts: 5595
#43

### Re: how fast was i traveling?

08/18/2008 12:49 PM

Now I'm sorry I brought it up! Hey, I didn't mean for anyone to interpret this as being the solution, all I meant was that it can't hurt your chances...

__________________
Veni, vidi, video - I came, I saw, I got it on film.
Off Topic (Score 5)
Power-User

Join Date: Jan 2007
Location: The Capital City, Cow Hampshire, USA
Posts: 476
#44

### Re: how fast was i traveling?

08/18/2008 5:41 PM

Actually, i think it can hurt. There are some, i believe, that take FTW loud noise as a trigger for agression. I've been a bike fan for ~40yr now, & detected behaviour that is bound to make bike + rider "road pizza".

__________________
If you always do what you've always done, You'll always get what you've always had!
Off Topic (Score 5)
4
Guru

Join Date: Aug 2006
Location: Midwestern United States
Posts: 843
#24

### Re: how fast was i traveling?

08/14/2008 3:00 PM

As mentioned previously in some of my posts, my second job is a Military Police Officer. I am currently certified to run RADAR, LIDAR and LASER speed tracking devices. Additionally my accident investigation training is current within the past 2 years.

First, related to your speed; the value that we are trained to put on your accident report is the only one that has some type of verifiable method obtained through documentable evidence; this would be your 'minimum traveling speed.' This number generally represents portion(s) of the event. For your situation you could have two different values.

1.) The minimum traveling speed at the time your skid mark started, and

2.) The minimum traveling speed at the time the bike was laid fully on the pavement.

Now, the officer will document how far you slid but this value will not play into his calculations. His calculations will include constants derived from:

1. Pavement Type - Asphalt, Concert, Gravel

2. Pavement Condition - Wet, Dry, Slope

3. Number of Times Vehicle Flipped - in controlled slides, generally zero

4. Skid Marks - length, width

5. Vehicle Type - make and model (from which he will be able to derive Curb Weight, etc.)

First, he will measure the distance that the bike slid once it was fully laid. He will then run the formula and determine that minimum traveling speed of the bike at the moment it started its fully-laid slide.

Second, he will use that speed as the minimum traveling speed at the end of the skid mark; any reduction in speed that occurred between the end of the skid mark and the point that the bike was fully flat can not be verified through objective evidence and therefore will not be considered. He will then calculate your minimum traveling speed at the moment you initiated the skid.

In most all states, traffic investigation is done through their highway patrol who posses software and database access through their laptops mounted in each vehicle. They enter in the known, and the computer spits out the number.

But, if you're interested in finding out a 'rough estimate' of what the coefficient of friction is of your vehicle... here's a process in how to determine it for a car:

At a set speed (say 30 MPH) lock-up the brakes. Measure length of all four tire skid marks (say 60, 62, 57, and 59.)

Add them together and divide by 4 = 59.5 average skid distance.

Square the speed 30 x 30 = 900.

Divide squared speed by average distance: 900 / 59.5 = 15.13.

Multiply by constant of 0.033: 15.13 x 0.033 = 0.4992.

You can then plot a straight line, using the below Speed Nomograph, from the length of the skid to your calculated skid resistance and you will get a minimum traveling speed. Obviously this is a very rough method of doing it. These days the software programs used have inputs for tire make and model, air temperature, ABS variables, etc.

Now that we've gotten that out of the way; I'm going to put on my law enforcement officer's cap and my motorcycle riders cap at the same time.

First, my qualifications to comment are: I have been a Military Police Officer, full or part-time, since 1985. I have rode motorcycles, both dirt and street, since 1976. I have been involved in multiple car/motorcycle accidents from both perspectives, and I have taught Motorcycle safety courses to those military personnel desiring to be permitted to operate motorcycles on military installations.

A couple things that stood out from your post are: "made a left out of her driveway" from this let's infer a residential area. She obviously pulled out into your path, from this we can deduce either she didn't see you (blind spot or she was looking for a car) and/or you didn't see her prior to her turn (blind spot or was not paying attention.) You don't know what your speed was thus you were neither operating your motorcycle in a defensive-driving mind frame nor making a conscious effort to abide by traffic laws by insuring you were at, or under, the posted speed limit.

Regardless of all the unknowns, you are both at fault. She is at fault for pulling out into oncoming traffic and you are at fault for failure to maintain control.

Something I'd like to share... I love riding my motorcycles, but I also like breathing. Every time I get on my bike I do so with the assumption that even though you may be looking right at me... you don't see me.

It is also very difficult to judge the speed of a motorcycle, regardless of if it is oncoming or if you are following it. Most motorcycles have a single head and tail light, it is much more difficult to judge the distance and relative velocity of an object that has a single focal point then it is of an object with two.

Motorcycles can also make quicker velocity changes without using their brakes and since most drivers tend to daydream, it is the illumination of the brake light that brings them back to focusing on the moment.

If you're on your bike and there is a car behind you and you slow down by down-shifting; you are not being courteous to the driver behind you because your brake light is for their information, not yours...

It's purpose is to inform them that you are slowing down. If you choose to slow down and deny them that tool then you are putting yourself at risk; especially considering that you only have one focal point, not two, which increase the amount of time it takes for them to realize that the distance between you and them is closing.

The same problem exists with approaching motorcycles, you have a single headlight which pretty much eliminates the ability to estimate your speed. And if there are no apparent land marks, it's almost impossible to determine your relative distance.

This leaves the driver with having to make assumptions. They will have to guess at what your speed is, and by default they will go with the average speed that the traffic on that road normally travels. And they will have to guess at your distance. All this guessing happens intuitively and in a split second. Any change you make in your velocity after they have processed the data will not register because there is no apparent indication of your velocity change.

As for Guest's comments, in post 17, about the stigma and preconceived perception of motorcycle riders. EDIT First of all I do not see how such a post would qualify for a "Good Answer" vote as it is both off topic and a matter of exaggerated opinion. Sorry, I read it too quick... his post was graded as "Off Topic" sorry for any confusion. END EDIT

Since I am both a law enforcement officer and a motorcycle rider, a significant portion of my life is spent dealing with negative perceptions, because... yes, they are out there... but, absolutely none of them are sever enough to prevent me from riding my bike, or stopping by a donut shop for a cup of coffee; and I've been stationed all of the US and Europe.

And I seriously doubt that the reason Guest does not own their 250cc scooter to commute back-n-forth from work is solely out of the fear of the public mistakenly identifying him as a murdering rapist.

Just like one negative action by a cop will give us of us a bad name, one bad action by a motorcycle rider will give all of us a bad name as well. But these negative perceptions are easily overcome by how you act.

As for the debate of why and how we enforce speed limits, I'll save that for another time as this post has already surpassed a readable length.

__________________
Reuters - Investigators found that the recent thread derailment in CR4 was caused by over-weight creatures of lore and request that membership DON'T FEED THE TROLLS.
Guru

Join Date: Jul 2007
Location: Fort Lauderdale Florida
Posts: 5708
#30

### Re: how fast was i traveling?

08/14/2008 6:08 PM

GA. Very informative from both sides of the handle bars.

Motorcycles can also make quicker velocity changes without using their brakes and since most drivers tend to daydream, it is the illumination of the brake light that brings them back to focusing on the moment.

I have some vehicles with Whelan LED stop/tail lights. One of the light patterns is Stop Alert. This will flash the brake light very fast two or three times, then steady on. The flash is only micro seconds, but very noticeable. Is that available to retrofit into a standard brake light socket? And is it worth it in your opinion?

In South Florida every law enforcement agency I know of is using white helmets.

I am not responsible enough to ride a motorcycle, but I have some friends that do and most swear that wearing a white helmet makes you more visible than any other color. The feeling is that people only give respect to motorcycles if they think the bike is law enforcement. Your opinion please.

__________________
Bob
Guru

Join Date: Aug 2006
Location: Midwestern United States
Posts: 843
#33

### Re: how fast was i traveling?

08/15/2008 3:01 PM

Thank you Bob C.

"Is that available to retrofit into a standard brake light socket?

I'm not sure about its availability for retrofit into an existing socket because whenever I've changed my lights, I changed the whole assembly.

But, if you don't want to replace an entire light bar assembly, you could simply add a modulator and use your existing lights. There are many off-the-shelf braking modulators available that will make your existing brake lights more noticeable.

"And is it worth it in your opinion?"

ANYTHING that increases awareness or contributes to drawing attention to you is greatly beneficial. A modulator goes for around \$30.00 US. The brand I use is "Back-Off" it cycles though a multi-flash and steady-state. I have lost count how many times a car has pulled up next to me to tell me that my brake light has a short. If it is apparent enough to prompt a driver to go out of their way to bring the flashing to my attention, then it obviously caught their attention. So... yeah... it is well worth it.

"...every law enforcement agency I know of is using white helmets. ...wearing a white helmet makes you more visible."

I do not know of any that use anything other than white or a metallic silver or gold color. And there are other reasons why white is used besides it being easier to see. Certainly it is the primary reason but others are: it's more professional looking and it reflects more light. I would hate to have to be out in the sun all day with a black helmet.

"people only give respect to motorcycles if they think the bike is law enforcement. Your opinion please."

Haha, in regards to peoples perception of law enforcement in general... "respect" would not be the first term that comes to mind. But I know what you mean, and yes... It is proven that 100% of all individuals that see a law enforcement officer will acknowledge their presence in some fashion whether they are in a cage 'patrol car' a bike, on a horse, or on foot patrol.

In regards to commuter traffic the default reaction is to let off the accelerator, most even brake, and then check their speed. The next is, if the officer is on the side of the road, is to give them space. And finally, especially if the driver was speeding, is to avoid eye contact and pretend to be doing something to show the officer that they we're NOT the reason they just decelerated 15 MPH.

But, it is a stretch to say that people 'only' respect motorcycles if they think they are law enforcement. Those individual that do not respect motorcycles do so because they either do not see them, or they do not know how to.

Those that don't see them are obviously unaffected by if they appear to be law enforcement.

In my original reply, I made mention of "looking for a car." Subconsciously, when a non-motorcycle-rider looks for oncoming traffic, they are looking for other cars. And even though they may see the motorcycle, it will not register mentally.

In a previous close call that I've had, about two weeks ago... I swear that I made eye-to-eye contact with the driver and they still pulled out in front of me. In my younger, more volatile, days I've kicked in many a car door and prompted many drivers to roll up their windows, put both hands on their steering wheel and stare straight at the traffic light, praying for it to change quickly.

Did that reinforce a negative stereo-type of motorcyclist in the eyes of onlookers? Probably. But, back then I wasn't thinking big-picture and I let my emotional reaction, that they almost killed me, take control.

With age and experience you learn not to let your emotions control you, but it still doesn't minimize the fact that their are idiots out there... both in cars and on bikes.

As for those that don't know how to respect motorcycles... it's our job, as motorcycle riders, to 'try' and teach them. For those that have negative perceptions of motorcycle riders... it's our job, as motorcycle riders, to 'try' to change their perceptions through our positive actions.

However, at the end of the day, people will think and act the way they choose and we can only do so much to affect that.

I know that every day I will have to deal with someone who looks down upon me, whether it be because I'm on a bike, responding to a domestic violence call, or searching their home for IED components.

But, I do not do what I do for them... I do it for me, or for the greater good... so they'll just have to deal with it.

"I am not responsible enough to ride a motorcycle"

That statement alone make you responsible enough... you may not have the skill or the knowledge to be able to get on a bike today. But, should the day ever come that you have a desire to... I encourage you to pursue it as there truly are few things that I have found that equal it.

__________________
Reuters - Investigators found that the recent thread derailment in CR4 was caused by over-weight creatures of lore and request that membership DON'T FEED THE TROLLS.
Power-User

Join Date: Dec 2006
Location: La Grande, Oregon U.S.A.
Posts: 468
#28

### Re: how fast was i traveling?

08/14/2008 5:36 PM

The only speed that matters here is that you outpaced the grim reaper. Everything else is trivial.

__________________
Don't hit at all if it is honorably possible to avoid hitting; but never hit soft! - Theodore Roosevelt
Anonymous Poster
#38

### Re: how fast was i traveling?

08/17/2008 8:05 AM

So you're trying to be your own attorney? What state or jurisdiction? Claimant or defendant?

Also, were you on your way to pick up milk? Or hurrying to take it home to your 4 hungry children who, along with yourself, were traumatized physically and emotionally from having to drink soda pop with your Twinkies?

Anonymous Poster
#39

### Re: how fast was i traveling?

08/18/2008 7:05 AM

You have to add speed of the earth surface and speed of the earth in its sun orbit, with proper sign for the direction.

Off Topic (Score 5)
Commentator

Join Date: Apr 2008
Posts: 73
#45

### Re: how fast was i traveling?

08/18/2008 8:25 PM

Hi all,

The rule of thumb that was mentioned several times actually comes from basic physics equations. We equate the kinetic energy before the skid (or the slide in this case) to the energy lost by friction while slowing down and stopping. Multiplying both sides of that equation by the acceleration of gravity allows the weight of the person or object to be cancelled from the equation. This absence of weight or mass from the equation is the main reason that people mistakenly call it a "rule of thumb".

You don't say if your bike slid 81 feet, you slid 81 feet or the two of you together slid 81 feet. Without knowing the condition of the road, your bike, and yourself, we can only guess at the coefficient of friction. However, with a reasonable guess in mind, and depending upon your bike or you being the object that travelled 81 feet, you were probably going between 25 and 45 mph. The police officer at the scene is likely to have a very accurate estimate of your speed since he was able to observe you, your bike, and the road conditions (well, at least after the accident). NOTE: This is applied only to your speed at the beginning slide and does not include any skid before the slide occurred. If a skid or braking occurred before the slide, your starting speed will have been that much higher.

Assuming it was the bike that slid 81 feet, you should have been able to stop your bike, using your brakes and not your pavement chaffing butt, in about 35 feet instead of 81 feet by sliding it. If you are what slid 81 feet, you could have stopped your bike in 70 feet or less by staying on it. Simple physics - I'll spare you reading and myself writing all the equations and numbers.

This brings up a HUGE safety tip for you and the other readers. Back in the early days of motorcycling - and I do mean EARLY days, tires and brakes were pretty poor. Consequently, it was in some cases safer to slide it and early motorcyclists were taught how to do this. Between that legacy and Hollywood movies the concept has been born that laying it down and sliding is the best way to stop. Au contraire! (my apologies to any French readers.) Staying on the bike gives you some control over the situation while laying it down removes any control you may have had. Also, and more importantly, brakes and tires have come a long way since the early 20th century. Using your brakes and if necessary a swerve are by far the best ways to avoid an accident or at least reduce the injury caused in an accident. STAY ON YOUR BIKES. Please feel free to contact your local motorcycle safety instructor or DMV if you feel you need proof.

If you laid your bike down without intending to, there are only two reasons for this and they are both involve operator error and lack of safety knowledge. Please go take a refresher in motorcycle safety course before you get back on a bike and possibly put yourself back in this situation.

Interested in this topic? By joining CR4 you can "subscribe" to