How fast can you stop. Have you tried?

[Badjelly]

Fastest stopping I ever heard of was the Vincent. 20 foot from 30 mph.

Hm, s = 20 ft = 6.1 m, v = 30 mph = 48 km/h = 13.4 m/s, a = v^2/2s = 14.7 m/s^2 = 1.5 g. Higher than I expected. Possibly higher than I believe!

[Badjelly]

Come on now, out with it. What is your A?

I'm working on it.

[davebullet]

Fast enough to have a friend (now wife) on her less than 24hr old brand new CB250 run in to the back of me.

Guys are always inventing new ways to pick up a chick

[Mikkel]

That's a very good point that I hadn't considered. I don't have a bike that will do 200 km/h, so I can't do any tests on this. How much deceleration do you think is achievable by a rider sitting up at 200 km/h? As much as 0.3 g?

It's hard to measure - but one of my mates has a naked bike he's had up to ridiculous speeds (excess of 250 km/h) and at that point he is hardly able keep his head level due to the forces.

And I can assure you that even at 150 km/h it makes a huge difference whether I sit upright or lean down over the tank on my motard.

Oh, never mind, I'm sure I can calculate the answer. Let's see rhoa = 1.25 kg/m3, Cd = 0.8, A = ...

Thou should know better than to dabble in the dark arts of fluid mechanics!


In the end, if you're going fast enough - no matter Cd, A, rho_air, or any other constant (as long as P>0) - you will be able to exceed 1 g through airbraking.

[davebullet]

Guys, Maths aside, I hate to tell you a 2 metre stop from 60 kph velocity is perfectly possible. You just have to have a concrete wall at the 2 metre mark (pun not intended).

[Dean]

Guys, Maths aside, I hate to tell you a 2 metre stop from 60 kph velocity is perfectly possible. You just have to have a concrete wall at the 2 metre mark (pun not intended).

i could do that easy ive done 70 kph and stopped from 2 meters on ma gn250 i dont wanna brag but i can also do endos

[HenryDorsetCase]

You guys are dreaming if you think you can stop a motorcycle in 2m from 60kph. If you can, prove it, video on youtube and I will pay you $500.

and by stop I mean controlled, upright and without hitting anything.

Anyone can stop from 60 kph in 2m, say you hit a parked car, or the concrete wall thats been mentioned.

Otherwise you are just showing how little you know, and how dangerous to yourselves and others you really are.

[Ixion]

Hm, s = 20 ft = 6.1 m, v = 30 mph = 48 km/h = 13.4 m/s, a = v^2/2s = 14.7 m/s^2 = 1.5 g. Higher than I expected. Possibly higher than I believe!

22.5 ft from 30mph. So say the expert testers of the (then) VERY respected 'Motorcycling'.

I've managed 8mtrs odd with ABS. Never had the opportunity to put the Vincent to the test personally. Very happy to do so if someone can oblige with a Black Shadow.

[Badjelly]

22.5 ft from 30mph.

The article you cite says "22 1/2 ft", not "22.5 ft". That's quite enough of your trying to bamboozle us with that new-fangled decimal notation, young lad!

And 22.5 ft is more than 20 ft, to the tune of one GST.

Still pretty impressive, though.

[HenryDorsetCase]

22.5 ft from 30mph. So say the expert testers of the (then) VERY respected 'Motorcycling'.

I've managed 8mtrs odd with ABS. Never had the opportunity to put the Vincent to the test personally. Very happy to do so if someone can oblige with a Black Shadow.

If someone was to lend me a black shadow there is no way I would be stopping till I got to about Westport. Then only for gas. Got to get it good and warmed up before practising the old braking drills y'know.

[NighthawkNZ:Me]

Yeah i have done a fair bit of practise with this, i could haul the zxr250 to a stop from 60kph in 2 metres.

Awwee fuck Al u so cool to break the law... the laws of physics (but not as we know it Jim) ... awwe gee you are good rider al to mecky for me...

[Dean]

You guys are dreaming if you think you can stop a motorcycle in 2m from 60kph. If you can, prove it, video on youtube and I will pay you $500.

and by stop I mean controlled, upright and without hitting anything.

Anyone can stop from 60 kph in 2m, say you hit a parked car, or the concrete wall thats been mentioned.

Otherwise you are just showing how little you know, and how dangerous to yourselves and others you really are.

fine then ill put up a vid of me going 70kph stopping at 2meters

nah im such a noob im my dreams more like

[HenryDorsetCase]

Lets just exercise our brain cell shall we?

Assume your bike has a 17 inch diameter wheel and is running say a 110/80 front tyre.

The diameter of the wheel is thus 17 x 25.4 plus 2 x (110 x .8) 431.8 + 88 +88 == 607mm.

circumference of a circle is pi x D

so 3.1415962 x 607 gives a rolling diameter of 1906mm.

So the statement here (I can stop in 2m from 60kph) equates to: "I can stop in ONE and a little bit wheel rotations from 60kph"

Someone who had never ridden a motorbike before might think that was possible, but anyone with any knowledge whatsoever would see the statement is completely flawed.

My $500 (which is real money by the way) is COMPLETELY SAFE.

[Dean]

Lets just exercise our brain cell shall we?

Assume your bike has a 17 inch diameter wheel and is running say a 110/80 front tyre.

The diameter of the wheel is thus 17 x 25.4 plus 2 x (110 x .8) 431.8 + 88 +88 == 607mm.

circumference of a circle is pi x D

so 3.1415962 x 607 gives a rolling diameter of 1906mm.

So the statement here (I can stop in 2m from 60kph) equates to: "I can stop in ONE and a little bit wheel rotations from 60kph"

Someone who had never ridden a motorbike before might think that was possible, but anyone with any knowledge whatsoever would see the statement is completely flawed.

My $500 (which is real money by the way) is COMPLETELY SAFE.

actually no im gonna take that 500 dollars from you .im making a vid

[RC1]

actually no im gonna take that 500 dollars from you .im making a vid

does the GN250RR go to 60 ??