Night Rider Stopping Distance!!

[Lineareagle]

I found the following web page and wanted to pass it on.

It deals with stopping distance versus speed and visibility.

Specifically for cars but applicable to motor riding really day or night.

How fast can you REALLY stop when you see that obstruction?

 

At 40mph when you see something in your low beams, in a cage, by the time you react and get on the brakes you've hit it!

 

web page

 

And thanks to the efforts of the UofO Police Department!

[jfremder]

Interesting Web Page. The braking distances seem more like that for a 18-wheeler. My cars and RT can stop from 60mph in ~120-130', thay show double that. The reaction times seem a little off too. Here's another example Stopping Distance

[chrisolson]

The differences are because the 2nd set of calculations assume a co-efficient of friction of 1.0 and a deceleration rate of 17.02 while the first are lower about .75 and 15.0.

 

Which is more accurate? The real world answer depends on road surface (concrete/asphalt/etc), tire condition (new/old/compound), physical braking system condition (type of pads/shoes) etc...

 

Most road test reports are optimised around all three + a known starting point that minimizes reaction time.

[ShovelStrokeEd]

There is another thing not taken into account in this equation. Rider is much higher than average car as are the lights. Properly adjusted, my main beam on the Blackbird reaches way down the road and, thanks to some good design by Honda, the dipped beam is actually at the top of the assembly and gives a very good light pattern.

 

Combine these two factors, add that I ride with two fingers covering my brake at night and the general heightened awareness of conditions an experienced rider develops to survive and the numbers start to look even sillier.

 

Always good to remind us not to outride our lights or to ride faster than our guardian angel can fly.

[Lineareagle]

awareness of conditions an experienced rider develops to survive and the numbers start to look even sillier.

 

Not sure that the 'numbers' are sillier. Perhaps the numbers become just that - numbers - the real world has a whole lot of surprises out there. How many times do we hear the phrase 'vehicle was within the speed limit'. The speed limit is itself just a number. Reaction times, surface conditions, tire pressures, rubber adhesion, fatigue, distractions etc all are just numbers or at least quantities that can, I suppose, be measured. The point is reduced visibility should equal going A LOT slower. In my experience it doesn't.

Always good to remind us not to outride our lights or to ride faster than our guardian angel can fly.

 

Precisely. Again I would guess that we all out ride our lights. I know I do. That is why when I tour I am on the road at sun up and off the road well before sun down. I just don't like the odds and especially don't like big odds like deer spoiling a good trip.

Besides, whats to see at night except scary shadows on the side of the road!

 

Ride Safe!

[ShovelStrokeEd]

158 feet from 60 mph isn't silly in the context of our bikes? Try 120 feet.

Covering the brakes will reduce reaction time down to 0.75 second, works for cars too.

Toss in a couple of HID's and/or good driving lights as many here use and your sight distance increases. BTW, thank your gummint, in the form of the DOT for the crappy lights on cars used here in the US. Europeans have long benefited from government policies that actually look at safety rather than giving the appearance of doing something safe. They allow much better lighting than the feeble glow we are permitted and actually use their dimmer switches. Of course, they also keep to the right except when actively passing but, that is a topic for another thread.

[Grayrider]

I think that they are figuring in the 1.5 seconds for a reaction time. It's been accepted that most people take approximately 1.5 second to perceive and then decided what course of action to take when in an emergency braking situation.

[pmdave]

Thanks for the references. And thanks for reminding us that braking is an important part of riding.

 

Although I have certainly observed some motorcyclists who must be in the "average car driver" response group, I suspect that lots of riders are both more observant of what's happening ahead, and quicker to make speed adjustments. I don't know of any tests or formal conclusions but I'd be amazed if many of us riding at night mile-after-mile could react to a hazard quicker than 0.75 sec even if we were covering the brake lever and wide awake. I suspect that the "normal" reaction time for a veteran motorcyclist is more like 1.0 sec.

 

We also need to add in some time for weight to transfer onto the front wheel before maximum braking can occur. That's included in the braking tests that show between about 115 - 125 ft for most motorcycles. That's 60 - 0, but the rider is absolutely prepared, knows precisely when the stop is to be initiated, and gets to do it over and over again until the minimum distance is achieved.

 

We should also note that braking distances (after reaction and weight transfer) are not equal for all machines. Sport bikes are often limited by the "stoppie" characteristics of a short wheelbase. And certain motorcycles have much longer than "normal" stopping distances due to peculiarities of the braking system. (The R1150 GS Adventure comes to mind, with distances up around 145 ft)

 

Yes, a powerful, focused high beam will help light up the road farther ahead, but won't light up the deer that's about to leap out from behind a tree.

 

Occasionally I find myself in circumstances of being on the road at night, but I try to avoid night riding these days. Age = degraded vision, slower reactions, and longer healing time.

 

pmdave

[ShovelStrokeEd]

Despite what you think, the reaction time is from the start of the event to the application of the control and includes the time to move the foot/hand. There is no way to measure when a person "decides". The paradigm has been used since they started measuring this stuff, and yes, covering the control cuts the reaction time in half, car or bike.

 

BTW, I would suggest, if your lighting is aimed and performs so poorly as to not illuminate a good portion of the verge and surrounding foliage as well as a good deal further down the road than the 160 feet quoted, you either get better lights or choose not to drive/ride at night.

[pmdave]

I guess if I want to continue riding at night, I need some of those X-ray driving lights that see through rocks and trees, huh?

 

pmdave

[ShovelStrokeEd]

Don't know about X-ray but I do know that good lights, properly aimed, make an enormous difference in what you can or cannot see when driving/riding. Perhaps one of our more archival minded folks can dig up David Baker's post on the lighting he fitted to his 1200 GS. The photo's speak for themselves. HID lamps plus supplemental lighting (also HID as I recall) make a huge difference.

 

I too, suffer the effects of older eyes. It does make me nervous when riding at night. I do take a few mph off.

 

BTW, that 145 foot distance quoted for the GS Adventure had more to do with the tires fitted than any short fall of the bike due to weight transfer and the like. Combination of a taller/narrower front tire and either a block pattern tire or possibly a dual sport type tire. I know the Tourance tires on mine had a tread more like iron than rubber. Routinely got 12K miles out of the rear and could probably have gone 20K on the front if I didn't prefer to change tires as a set.

[Horse]

Interesting Web Page. The braking distances seem more like that for a 18-wheeler. My cars and RT can stop from 60mph in ~120-130', thay show double that. The reaction times seem a little off too. Here's another example Stopping Distance

 

http://www.highwaycode.gov.uk/09.htm#105

 

Here in the UK we have a Government Publication called "The Highway Code", stopping distances page linked above.

 

There's a simple reminder for working out the overall stopping distance:

 

20mph x 2 = 40feet

30 x 2.5

40 x 3 = 120feet

50 x 3.5

60 x 4 = 240feet

etc.

 

Where the 'thinking' distance (ie reaction time) is given as the same in feet as the speed, roughly 0.7 second.

 

These figures have not been changed for many years.

[tallman]

I submit that stopping distance is much longer than any of us "think".

Throw out test results when the test was for braking.

That's in optimum conditions. Never happen in the real world.

Don't kid yourself.

Those bikes had new rubber, new brake pads, professional riders, controlled environments.

Night time?

Some studies show that stopping is faster, in some cases, due to recognition factors. See cite below.

 

 

http://psyche.cs.monash.edu.au/v5/psyche-5-03-mack.html

 

In his classic "On The Speed Of Mental Processes," Donders (1868) proposed a classification scheme that experts still use to distinguish among three different types of reaction time, simple (Type A) and more complex situations, choice (Type B) and recognition (Type C). While most of the variables affect simple and complex types in the same way, choice and recognition reaction times each add new factors that must be also be considered.

http://www.visualexpert.com/Resources/reactiontime.html

 

Accident reconstructionists have a wealth of real world data that suggests it takes longer, much longer to stop in the real world.

Try this.

Have a friend choose when and where to pull out from a side street.

They need to measure distances beforehand so they know where 30, 45, 60, 90, 120, etc, feet from the intersection is.

T intersections work best with you having the right of way.

Make sure they are in a vehicle you don't know.

When you get to the predetermined (their choice) distance from the intersection they pull out and block the road.

Bonus points if they choose a location around a curve, over a hill, with sand/gravel on it.

Good luck.

Best wishes.

[Albert]

Sadly (since the night was always one of my favorite riding times) I've almost completely given it up. According to one insurance company's statistic (see latest Rider magazine), last year Pennsylvania had the highest incidence of deer/vehicle collisions in the US. That combined with my aging eyes means I rarely venture into the night on two wheels anymore.

[pmdave]

 

BTW, that 145 foot distance quoted for the GS Adventure had more to do with the tires fitted than any short fall of the bike due to weight transfer and the like. Combination of a taller/narrower front tire and either a block pattern tire or possibly a dual sport type tire. I know the Tourance tires on mine had a tread more like iron than rubber. Routinely got 12K miles out of the rear and could probably have gone 20K on the front if I didn't prefer to change tires as a set.

 

The scuttlebutt at MCN about the 1150GS Adventure stopping distance of 145.7 feet was that the ABS seemed to activate sooner, lengthening the stop. Of course, ABS would activate because the front tire was starting to lose traction. The Adventure comes shod with more dirt-oriented tires than the standard GS. My own experience riding an Adventure in South America indicates that the combination of skinny hard tires and ABS does not provide confident stopping power on pavement.

 

By comparison, the same MCN crew tested the '98 1150GS at 130 ft, and the '04 R1200GS at 125.2 ft. The '97 K1200RS stopped in 114.6 ft. The '06 Triumph Speed Triple stopped in 104.8 ft.

 

There must be a moral to all this, if we could only figure it out...

 

pmdave

[ShovelStrokeEd]

I put 74K miles in 2 years on my '04 GS Adv and the funny thing is that I never considered it to be deficient in stopping power. I did notice the intrusive power assisted brakes and its ability to ride over small critters without the need for said brakes.

 

I broke it in with a 750 mile day and immediately fitted a honking big set of PIAA lights to it as I had to strike a match to see if the stock headlight was on. I wonder if the angle between the rider's eyes and the centerline of the beam from the headlights has anything to do with the efficacy of the system. Not talking lumens here, just ability to see stuff. Time for some research, I guess.

 

I own and ride a number of different bikes and, I guess, just automatically adapt my riding habits to the bike that is under me. I do leave a little more room when riding the '78 R100S or the '91 Guzzi when compared to say, my Blackbird or the VFR. That R100S, btw, has a great headlight for its time. Big, round and a good lens. Again, maybe head position relative to light position might have something to do with it.

[philbytx]

Wow! PA first?

 

Man, does that mean we have smarter riders in Texas???

[Albert]

Wow! PA first?

 

Man, does that mean we have smarter riders in Texas???

 

Without a doubt. You also picked a place with a longer riding season.

[philbytx]

Without a doubt. You also picked a place with a longer riding season.

[Eckhard Grohe]

More poachers???

[Pilgrim]

More poachers???

 

One can only hope! I wish they'd make poaching legal and thin out the herd in the lower 48. 'course, then it would be legal and nobody would want to do it.

 

Pilgrim

[St_Louis_Don]

Wow! PA first?

 

Man, does that mean we have smarter riders in Texas???

 

A recent study indicates deer in Texas have a lower rate of depression then deer in Eastern States. Directly relating in a lower rate of suicidal deer in TX.

[Rags]

Wow! PA first?

 

Man, does that mean we have smarter riders in Texas???

 

A recent study indicates deer in Texas have a lower rate of depression then deer in Eastern States. Directly relating in a lower rate of suicidal deer in TX.

 

Can't prove that by me. I was doing about 75 @ 1:00am when I hit something with my left peg foot. It was a deer carcass. It twisted my leg inward to hit the bike - oouch!(bike had no loss of control). I figured I broke the leg so I got off I10 at my first opportunity which was near Sheffield TX.

 

A couple of days later I passed the same spot and there was a big buck broken on the road (within 1/8 mi of where I clipped the doe). I didn't see any deer signs going east but saw two going west.

 

I like night riding but my biggest fear are deer.