Jul 30, 2007

Sliding front: emergency maneuvers

Yamaha YZF-R1 Front BrakeSo, you need to brake hard, you use the front brake and now the front's sliding, is it game over? In most cases, unfortunately, yes, the game is over. You're a passenger now, and you're gonna get what's coming. But hold on. There is one thing you can do. It isn't easy, it takes a lot of guts and it may not actually change the outcome, but you really should try it.

Why did the front lock up? Braking force, or rather maximum braking force is a trade-off between the available traction at the contact patch and the available traction between the disc rotor and the pad. When the latter overwhelms the former, you got a lock up. So now that you have lock up, what do you do? You reduce the traction between rotor and pad and the wheel should start rotating again. Simple, right?

Not quite. What separates the men from the boys is how much pressure you release. The boys will tend to let off the front brake completely. Result? You fail to stop entirely and crash into whatever you were trying to avoid. The men, have practiced enough/are skilled enough, to release only a tiny bit of pressure... the exact amount needed to get the front wheel turning again. Nothing more. How close you can get to this is a function of how skilled you are. Do it perfectly and could probably outbrake Alex Barros.

Unfortunately, there is no way to actually practice this without falling off a couple of times at least. So what you do is practice braking hard, and then letting off some pressure to see what it feels like. I like to do this braking to a stop at traffic lights when there isn't anyone on my tail. I brake as hard as I can – just short of a stoppie – then start varying the pressure. Without letting off the front completely at any point, I try to modulate brake pressure towards a set goal. Like stopping an extra 10 metres ahead after having braked really hard (failure is stopping early).

Just watch for one thing. If you've let the brake off completely, you cannot grab a handful again. When you released the brake, the forks would have extended again, and you need to reapply pressure progressively. Grab the brake now, and you'll go down in a heap... just what you were trying to avoid.


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10 comments:

aditya said...

Holy (#)$ now thats a scary excercise

will try out @ the earliest

John Sarkar said...

Common Sense

Hrishi said...

Or, what you can do is emulate the ABS. For this, you modulate the brake lever as fast as you can. That ways, you get maximum braking, as well as some control over the front.

Its a lot safer than just "braking till the front locks"...

Just my 2 cents...

Revhard said...

Right on - modulation is the key and very difficult one to get right. After re-test riding an Apache ( in the wet this time) I decided let's try to brake hard on my Karizma. Went on progressively harder until I got a headshake. I though I'd lost the front but the bike straightened up immediately as I relieved some brake pressure .

Point to note : The Apache gives immense feel & feedback from the brake that gives great confidence in braking hard on the first ride itself. Something my Kari still isn't that good at. What you ride may well also save you !

The BATFAN said...

Well no doubt the men are those who pull those stunts which always involve skidding and then regaining back the control. I always wonder how they do it as I would think it needs time with a machine to do it. But recently at a Yamaha convened Test Ride Galla I saw two stunt men pulling stunts at will. I am not sure how much time they had spent with the bikes. What most particularly impresses me is the skidding rear to turn tight and then gain back control.

Do you need to tune a machine for all these stunts or you should tune yourself to gain confidence on any bike to pull these off. I feel scared like a rabbit sitting on any bike now but on my own I know I may not be a lion but at least I can save myself with confidence and I have done it some times now in the nearly 8500 KM that I have tracked up in 10 months. I think that the experience is what trains you the best. If you save yourself you learn something new and if you fall you analyze what you need to learn and then learn it better.

I gotta say driving is such a dud in front of riding.

nEo said...

But the hardest thing is to keep our mind cool to do all this stuffs in such a panic situation. U said it right , boys cant do it ;)

Hrishi said...

@ the batfanWhat most particularly impresses me is the skidding rear to turn tight and then gain back control.

Have been through this, accidentally of course.
Then on, used to do it quite frequently on my first bike - THE KB100. What you do, is just hit the rear brake, causing the rear tyre to lock and try to outrun the front. To snap it in line, just release the brake, and it rights itself up.

PS: Haven't done this a lot on my P180.

The BATFAN said...

Well I too have done it accidentally to avoid hitting an opposite floating Indica speeding into my lane in a right cut. To a pedestrian it would have looked a neat stunt but my heart had stopped and the mind was running fast at that moment.

To do it in a controlled manner is indeed a skill I would love mastering because a stoppie and a wheelie are after all just stunts but to control a sliding rear can be a life saver.

Anonymous said...

i used to practice this on my scooter o a deserted stretch or road near my house. i used to brake as hard as i could without locking up and progressively upped the pressure till it locks up and then tried staying at that limit. i've done some panic stops after that and i'm proud to say that the front hasn't locked (due to rider skill or work out brake shoes, you decide)

The BATFAN said...

This ain't good man...

You seem to be posting a lot 500 was the last milestone right ...

And yet I feel there you are not telling us about the real aspects of motorcycling like the one you talked about in this post.

You & I both know that there would be launches and launches of 100 cc commuters and I think it would be great if you don't cover them unless of course one of them turns out to be a true romper and revolutionary bike (@100cc I am guessing that would be hard).

Give us more of You are warned kinda stuff ;). Was going through MSGroup.org yesterday and found that he had this article about making leaning easier for beginners. They said that you should turn the handlebars to their full and push off like that. I tried that and found that it did not require me to lean sufficiently though I did not go in circles of course and straightened the handle after three to four seconds. Was I doing something wrong.