GSA Stopping distance.

[GrinningGSer]

GS' have phenomenal brakes. It's the front that is your stopping tool, but use it with skill,weight transferred forwards before full on. Watch those MOTO GP riders braking into a corner with their rear wheels off the ground. The rear brake is the devil's toy.

 

[snerkler]

GS' have phenomenal brakes. It's the front that is your stopping tool. Watch those MOTO GP riders braking into a corner with their rear wheels off the ground. The rear brake is the devil's toy.

Obviously it's the front brake that stops you, as I said I thought he was also using the front brake in that vid

 

[Mutley]

I did the i2i machine control courses a few weeks back. One of the exercises was progressively braking harder and harder. I was managing stoppies on my 1150gs and pulling up faster than the guys with ABS brakes.

Most people never, ever brake as hard as they could, as they've never gone and properly practiced it. I was astonished to hear the 'clang' of the rear end coming back down.

If you want to learn to brake really effectively, go and get some tuition or find an empty car park and progressively increase your braking effort. I now practice when I can and I'm constantly impressed by how fast my 1150 will stop if I give it full anchor.

The thing is you don't do emergency stops for real in 'exercise conditions', you do them in the dark and wet when you are knackered and you've misjudged it and panicked. I bet my ABS wins then

 

[littleredrooster]

From a bike mag several years ago and not a GSA but GS

I think the brakes are fabulous

Thank You. That's the one - my memory was playing tricks when I said it was the GSXR-1000.

I too think the brakes are fabulous. Nothing better than leaving a dotted black line from the front tyre when steaming into a roundabout past all the heroes.

 

[Wapping]

Any idea where one can find this animation?

Google: animation telelever bmw

http://www.google.co.uk/search?clie...oe=UTF-8&redir_esc=&ei=iLThTq2NMsTP8gP599ifBA

 

[karlp]

Thank You. That's the one - my memory was playing tricks when I said it was the GSXR-1000.

I too think the brakes are fabulous. Nothing better than leaving a dotted black line from the front tyre when steaming into a roundabout past all the heroes.

It would be interesting seeing this graph plotted as stopping distance vs mass of motorcycle

 

[snerkler]

Google: animation telelever bmw

http://www.google.co.uk/search?clie...oe=UTF-8&redir_esc=&ei=iLThTq2NMsTP8gP599ifBA

Thanks, but I still can't find an explanation as to why the front 'dips' with rear wheel braking

 

[Beemerman59]

Thanks, but I still can't find an explanation as to why the front 'dips' with rear wheel braking

My guess is that the rider has gone from acceleration to off throttle at the same time as hitting the rear brake. The deceleration would also cause the front end to drop slightly. When you accelerate, the front end rises so I would expect the opposite to happen when coming off throttle - what goes up must come down.

 

[Yonkyo]

I know this is an Ad for Conti tyres. But fast forward the video to 1.25+ and see what you can do with the power of the front brake (if you have the skills).

<object style="height: 390px; width: 640px"><param name="movie" value="http://www.youtube.com/v/lhVpXGqocX4?version=3&feature=player_detailpage"><param name="allowFullScreen" value="true"><param name="allowScriptAccess" value="always"><embed src="http://www.youtube.com/v/lhVpXGqocX4?version=3&feature=player_detailpage" type="application/x-shockwave-flash" allowfullscreen="true" allowScriptAccess="always" width="640" height="360"></object>

 

[snerkler]

My guess is that the rider has gone from acceleration to off throttle at the same time as hitting the rear brake. The deceleration would also cause the front end to drop slightly. When you accelerate, the front end rises so I would expect the opposite to happen when coming off throttle - what goes up must come down.

This doesn't explain why the front 'pops' back up when he's stopped though

 

[Beemerman59]

This doesn't explain why the front 'pops' back up when he's stopped though

My guess, again, is that the front has dropped at the time of the initial deceleration. As the rider brakes with the rear, the whole bike is decelerating so the front end will stay lower than it would be at rest or constant speed. So, when the bike does stop it would equalise itself again by the front end rising up.

 

[mikeyboy]

Thanks, but I still can't find an explanation as to why the front 'dips' with rear wheel braking

torque reaction and weight transfer

 

[snerkler]

The joys of physics eh? And to think I studied A-level physics, obviously learnt a lot Must admit, would have been much more interesting if we had studied things like the effects of braking on a motorcycle

 

[EggChaser]

I think you can see the effect for yourself riding along and brake to a stop (or close to a stop) using just the rear brake. Then just before you release the brake get a reference from your eyeline across the top of the screen to something ahead and then release the brake you should see the front rise slightly.

Not into physics in a big way but in effect the braking force is through the pivot of the swing arm when you use the rear brake. The two heaviest objects that are above or behind this pivot point are the fuel tank and the rider (the engine is more or less in front of it.) Now if we assume that fuel tank and rider are solidly fixed to the pivot (I know the rider isn't exactly) then as you break at the rear wheel won't momemtum of the rider and tank try to swing around the pivot and therefore push the front end down (and the rear end up) but not to the same extent that front braking does. Admittedly this would be true for normal bike suspension too but could partially explain the curtsey/dip. Luggage would of course potentially add to the effect.

 

[snerkler]

I think you can see the effect for yourself riding along and brake to a stop (or close to a stop) using just the rear brake. Then just before you release the brake get a reference from your eyeline across the top of the screen to something ahead and then release the brake you should see the front rise slightly.

Not into physics in a big way but in effect the braking force is through the pivot of the swing arm when you use the rear brake. The two heaviest objects that are above or behind this pivot point are the fuel tank and the rider (the engine is more or less in front of it.) Now if we assume that fuel tank and rider are solidly fixed to the pivot (I know the rider isn't exactly) then as you break at the rear wheel won't momemtum of the rider and tank try to swing around the pivot and therefore push the front end down (and the rear end up) but not to the same extent that front braking does. Admittedly this would be true for normal bike suspension too but could partially explain the curtsey/dip. Luggage would of course potentially add to the effect.

Makes sense. Will have to try this out for myself when my arm's better

 

[E. Buygum]

Thanks, but I still can't find an explanation as to why the front 'dips' with rear wheel braking

Under deceleration, the bike's weight is transferred more to the front, which compresses the front suspension. (The opposite applies, of course, under acceleration). It doesn't matter what causes the deceleration: front wheel braking, rear wheel breaking, hitting a tree stump...

 

[CuzGS]

Deceleration doesn't exist, it's acceleration in another plane

Pedant police alert

 

[AdamA]

Deceleration doesn't exist, it's acceleration in another plane

Pedant police alert

No it isn't, acceleration in another plane would be turning.
If the bike is simply slowing in a straight line it's negative acceleration in the same plane.

Policing the pedant police.
Just call me the pedant's complaints commission.

 

[snerkler]

Taken direct from educational literature

"Things can slow down as well as speed up. Deceleration - slowing down - just means that the change in velocity is negative."

 

[Steptoe]

Remove all the kitchen sinks bolted to the bikes and it'll stop even quicker.