Right then, it's late and I've had a few .......but by my dodgy calcultations, it would take 0.16 of a second to take anything from 60mph to zero in 4 metres......doubt even a formula 1 car with its acres of rubber etc. could do that, let alone a motorcycle stood on its front tyre

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Mithered ta death.
92 MB
96 S2T
98 S1W
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03 P3
10 CR

No I am not. I am saying I can with MY bike, in a very practiced way, but not in a normal road riding situation as its not practical.

I have always done this to test the limits of the suspension/braking system of my bikes so that I understand those limits. 60 to 0 in less than 4m is fine for me as a max effort. I have no idea what it should be its more of a "I do that in town and need to stop that quick" sort of thing.

Thats fair enough Maz. I am not questioning your numbers or have any axe to grind. Maybe its just my 20 years of London riding and a need to keep alive. I do tend to tune my bikes for suspension and braking though.

Also the use of a balanced suspension and, I know you think otherwise, a good rear brake, to balance the braking/bike load, is the key.

Anyway its good to here from you. What is your tipple tonight .

I read a test on braking distances between an R1, Fireblade and ZX10r, all from 60mph and the ZX10R took 123 feet to stop and that was on a track. The best braking car was the Veyron and that was 60-0mph in 103 feet.

Its quite clear that I have no idea what I am on about and seek help from a Pro.

Sorry Dutchman but you aint getting away with this one.......at 60mph, you're doing 26.8 metres per second......with all the practise/will to live/experience in the world, there's no way you could stop in 4 metres unless you hit something solid.

Rear brake does nothing when you're in a hurry to stop, as any application of the front brake transfers bike/riders weight onto the front wheel and leaves the rear very light/off the deck.

Vodka, as usual.

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Mithered ta death.
92 MB
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00 M2
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03 P3
10 CR

No need to be sorry Maz or that I am getting away with anything.

I, like many people, have many faults but one is not a liar. In younger days I might have needed to make the point but now I could care less. I stated a fact, will prove it to anyone here, as normal to me. 60 mph on a bike is nothing to me but thats just me.

From equations of motion:

v^2=u^2+2as

where:

v=final velocity
u=initial velocity
a=acceleration (or deceleration)
s=distance travelled

v=0 cos we are stopping
u=60mph or 26.822 metres per second
a=?
s=4 metres

a=-u^2/2s = 26.822^2 / (2 * 4) = -89.927 (got to be accurate in this game) m/s^2

WTF does that mean to Joe Public? Not much, so lets put it in terms of "g"

a = -9.2g

So the forces you exert stopping from 60mph in the length of a car are more than Eurofighter can pull in it's combat envelope...

The limit to deceleration on a straight run, on a good road in the dry will be looping the bike forwards, where the torque applied by the front brake against is greater than the product of the mass of the bike and rider and the distance of the centre of gravity from the front wheel spindle. The torque needed to be applied by the disc can be calculated as half the average diameter of the disc multiplied by the force needed to brake at 9.2g. The force needed can be calculated from Newton's Second Law: force = mass x acceleration... blah blah blah...

I am sure Performance Bikes did some tests recently on wavey discs etc. and I think they will have recorded g data at the limit.

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08 Specialized Langster

http://www.msf-usa.org/imsc/proceedings ... stance.pdf

Last page
A VFR800 with ABS at 48 km/h (30mph) stops using both brakes in 11.37 metres. Tested a few other bikes with both, front and or back brakes and all the results are 11-12 metres at 30 mph.....

Come on - 4 metres is 2 person-lengths - at 60?

At 80 mph these bikes are taking north of 70m to stop.

After re-reading my post its 30 not 60. I was thinking about something else .

Soooooooo sorry Gents. What a .

Im off to stick my head in the Microwave .

60mph - 0 in 4 metres??? Sorry Dutchman, you're wrong. At 60mph, you are doing approximately 90 feet per second. You nor anyone else, Rossi included, can't stop from 60mph in approximately 13 feet!


The following is a talk by Mr. Justice Blair, recorded in “The Listener” and copied from “The Journal” of Criminal Law, No.5 January, 1988.

The basic cause of road accidents is widespread ignorance of ground speed, not only on the part of pedestrians but also on the part of virtually every driver of a motor car, and I add that if this widespread ignorance on the part of the road users be cured and it is curable, then there will follow a great reduction in the toll of road accidents. A speedometer does not tell anyone his ground speed. It does nothing of the kind, and it is because every motorist deludes himself into believing that a speedometer tells him how fast he is covering the ground that the danger or road accidents is increased. A speedometer gives you your speed in miles an hour. Have you any mental picture of the length of any hour or the length of a mile? No one has. How then, can anyone possibly get a mental picture of his ground speed when he is asked to put two unreliable factors together and obtain a result?

I have tried very many running down cases. Judges are conscientious when trying cases and I always felt that in order to understand any motor case it was necessary that I work out a respective speed of each vehicle in a measure that would tell me their respective ground speeds. The only measure that would give me any mental picture of the speed at which a vehicle covered the ground was the measure of feet per second. That involved me in a lot of Arithmetic. Sixty miles per hour works out at 87.9 recurring feet per second and every time I converted miles per hour into fee per second I got a result in recurring decimals. So then I had to look for a simple formula, and this is how I got it.

Instead of calling 60 mph 87 odd feet per second I called it 90 feet per second and that gave me the simple formula of adding half to my miles per hour to obtain speed in feet per second correct within 2%. Ever since then, I have driven cars and tried running down cases in feet per second. Now what I say to all motorists is that they try doing what I do, that is always to drive and think in speed in feet per second instead of in miles per hour and you will at once become a 100% better and safer driver. All you have to do is to add one half to the figure of your speed in mph and you will get your speed in feet per second.

Any child can do that. The other aspect of road safety touches what is called kinetic energy, which means the moving force possessed by a vehicle in motion. I cant give you a more detailed explanation, but another way to put it is to refer to kinetic energy as the kick possessed by a moving vehicle. A small motor car weighing about a ton and moving at a speed of 40 miles per hour strikes the same blow as eighteen ten ton steam rollers travelling at their highest speed, which is 3 mph. That is the force you are handling when you speed up a light car to 40 mph 60 feet per second. If you are driving a big seven seater 2 ton car at 60 mph (90 feet per second) its kinetic energy is more than that of 100 ten ton steam rollers moving at 3 mph.

“Feet per second” and “Kinetic Energy” do not occur to most of us, until after the accident.

I have the whole table for speeds and stopping distances, but as 60mph has been chosen, here is the results for 60mph.

l-----Speed-----l-Multiplier-l-Braking Dist-l-Thinking Dist-l-Stopping Dist-l
FPS--MPS---MPH-----x-----Ft-------Mtrs---Ft-----Mtrs---Ft----Mtrs
90---27.45---60------3----180------54.90--60----18.30--240---73.20

Phew! had me worried there. I thought I had the record in my Citroen GS at 60-0 in 5.9 metres!......

Blimey, 'A' Level maths at 6:16 am, I can't even figure out how to make a brew at that time in the morning

Some years ago, Mrs Adam stuffed in an aircraft whist doing a 'touch and go' routine for her PPL. Hers was more touch than go and after measuring the start of the skid marks (on the airfield ) and estimating the speed of the aircraft in its landing configuration (about 45kts) someone worked out she must've pulled about -10g. I forget the actual figures but remember the weals the harness left on her body for a few days afterwards. Her Log Book has an entry by her instructor - 'Very heavy landing, aircraft destroyed'

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If your dreams don't scare you, they are not big enough.

'O' Level I'll have you know...

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08 Specialized Langster