Emergency braking: Clutch or de-clutch?

[javawocky]

Just typical, few minutes ago while riding in the lightly wet conditions Carpet Court sales rep suddenly changes lanes into median strip which I was on. Was already slowing about about 40kph and had to - sort of - emergency brake.

Think I followed my own advice? No I pulled the front the clutch and the back, locking the back up a little on the wet pain. However the front was where my attention was, applying enough but not too much to lock it up.

Which got me thinking on the rest of the ride back...

This whole discussion changes heaps when you consider the speed from which you are stopping. From hight speeds, like on a track you want the back turning to keep you pointing in the right direction.

I don't want the back coming around on me when going at high speed, its just dangerous. I think at slow speeds its far less of an issue if you get a rear lockup.

Interesting discussion which will no doubt be derailed by Katman at any moment.

[CookMySock]

You can't emergency brake hard mid corner in the situation you describe. The bike needs to be upright and the rider balanced before commencing emergency braking. If you are mid corner and commence an emergency brake the bike will stand up and there is a good chance you'll go wide on the corner and go off the road.

You don't get to choose. Nature will choose the moment and if you are going to argue that its "outside the rules" then it's going to slap your face with it at the least expected moment. Thats the nature of the beast.

You can emergency brake mind-corner. What you cannot do, is use 100% of what you had when upright, and therein lies the maths.

All of this is up to the end user to evaluate for themselves. Get on the track and belt the bike into corners and brake and note what it does. Yes it will alter its geometry, and yes you better figure it out, or else forget all this development-riding crap and just tour around quietly and hope you never need it.

[george formby]

You don't get to choose. Nature will choose the moment

Exacary how I think about it. Tis why you have to think how you react. Through awe inspiring talent & mind boggling skill ( pure luck + 20 odd years riding ) I had to throw the anchor out mid corner & stayed up, I hit the back brake hard, the front not particularly & as the bum swung round & the bike stood up managed to load the front up enough to avoid the car reversing at me without crossing into oncoming traffic. Not nice & I was not thinking about what the most effective way of stopping was, just about avoiding the multiple ways I could hit a car. Doing about 70kmh at the pucker point & I do not want to try it again. Wide bars & extra suspension helped more than technique I think...

[Brett]

Personally I always disengage the clutch on hard emergency stops. Firstly, rear wheel is usually only just skimming the ground anyway, secondly...if emergency braking near or around bends, swing arm chatter is a bitch. Anyone who has ever done some fast road/track riding knows the feeling of going into a corner too hot or dropping down gears a tad early and getting the arse end bouncing around like J-Lo.

Of course, if you have a slipper clutch the above is mitigated to a certain degree.

[Brett]

As Javawocky said...speed is a big factor. high speed, fast stops I leave clutch enganged. slow speed, around town e-stops I dis-engage.

[Usarka]

I don't want the back coming around on me when going at high speed, its just dangerous.

Disagree. Sports bike riders always like to brag about how big there balls are saying they don't need the rear brake because they brake so hard the back is off the ground. If you can manage an airborne rear tyre under braking then you should be able to manage a locked rear tyre. If your worried about what happens when you come off the rear brake, then DON'T!

In the context of an emergency upright maximum braking stop a locked rear wheel is not high on the list of priorities. If you're not upright you shouldn't be maximum braking. If you are and it locks leave it locked. IMHO & taught by prof instructors.

[p.dath]

And that's how I started. I'm saying the camber of the road is what I think caused the bike to slide out to one side. Now while I have control over whether my rear brake is locked or not, I sure don't have control of the shape of the road under me. Perfect world techniques are rubbish, especially in New Zealand, because we are so rarely on perfect roads in perfect conditions.

To suggest that practising emergency braking is pointless (is that what you are suggesting - not sure) because it doesn't work out in some scenarios is not a good reason to give up on learning how to do it.

If the rear wheel were to lock regardless of clutch in or out, how would that make any difference to the stopping distance? (Note this is using your argument, not mine, I still don't think the rear should be locked at all)

Because the rear wheel takes longer to slow down (and lock) when it is being driven by the engine. Even if you don't lock the rear wheel, you still don't want to be driving it using the engine during an emergency braking session.

have you read the article in the OP? There was half a meter difference over 40m, I don't think the testing done is enough to say that pulling in the clutch is better in the best case scenario, and no evidence to say it is better in others.

I did. In fact, if you read my BLOG on emergency braking you'll see I sited it a year ago. So yes, I am well familiar with it.
I guess I have watched a lot of people practising emergency braking, and have observed the impact it makes when pulling in the clutch.

But back to the article, in the worst case your no better off, and in the best case you'll stop in a shorter distance. Sounds a good reason to do it to me ...

You don't get to choose. Nature will choose the moment and if you are going to argue that its "outside the rules" then it's going to slap your face with it at the least expected moment. Thats the nature of the beast.

You can emergency brake mind-corner. What you cannot do, is use 100% of what you had when upright, and therein lies the maths.

All of this is up to the end user to evaluate for themselves. Get on the track and belt the bike into corners and brake and note what it does. Yes it will alter its geometry, and yes you better figure it out, or else forget all this development-riding crap and just tour around quietly and hope you never need it.

To me, emergency braking is bringing a motorcycle to a stop in the minimum distance. It may mean something different to you. Perhaps that is where we are at odds.

From my point of view, the fact that emergency braking is required at all is only because the rider has failed to notice they are entering a situation of increased danger, and have failed to respond to that threat. I know we don't agree on this one, but I don't believe it's natures choice when your going to get into trouble - it's the riders for failing to be aware of the situation - at least 99% of the time.

I've had plenty of track training sessions. "Belting" into a corner and using your brakes on the track has nothing to do with trying to bring your motorcycle to a stop in the shortest distance. Braking on a track (and granted, it is hard braking) is all about setting yourself up for a set of corners.

Emergency braking is about responding to something that you didn't expect. Something you didn't plan. Do see how this is quite different to braking on a track?
Emergency braking is about shedding a lot of speed because you have to - because you have no choice - because your life might depend on it.


As I say, we'll have to agree to disagree.

[george formby]

Braking threads are always good for different points of view & schools of thought.

For novice riders reading this may I just say that THE most important thing is practice & training.

As you were.

[bogan]

But back to the article, in the worst case your no better off, and in the best case you'll stop in a shorter distance. Sounds a good reason to do it to me ...

What is the confidence interval on their results though? In the best case you may be better off, and in the worst case you may have the back swing round on you. I reckon leaving the clutch alone may provide benefits in non-ideal situations, and pulling it in only provides small/negligible benefits in ideal situations.

After thinking more on it, I think (hard to recall as I don't have many oh fuck moments) I leave the clutch alone at higher speeds, and pull in at lower (though this is usually a conscious decision so I don't stall I think).

Obviously it makes more sense to learn and use a single technique only, so which one is best for all emergency braking situations?

[cheesemethod]

To suggest that practising emergency braking is pointless (is that what you are suggesting - not sure) because it doesn't work out in some scenarios is not a good reason to give up on learning how to do it.

No, I definately agree on practicing it. Just saying that my personal preference is to stay in control therefore have more options, even if it costs me another foot or two of road. I prefer to develop a skillset keeps me safe regardless road and environmental conditions. In my opinion the safest way for me to do that is not to lock the rear wheel and to keep the engine at the ready.

[Crasherfromwayback]

Because the rear wheel takes longer to slow down (and lock) when it is being driven by the engine. Even if you don't lock the rear wheel, you still don't want to be driving it using the engine during an emergency braking session.

The rear wheel isn't being driven by the engine when the throttle is chopped from revs. Im sure you've noticed your bike slow down when you only shut the throttle down...It's called engine braking.

[Ocean1]

First the brake gently and squeeze it progressively and smoothly harder to avoid locking the front wheel.

Yes, get more weight on the front so it'll take more braking force, which gets more weight on the front....

I remember seeing several surveys done by reputable sources about whether to grab the clutch in emergency braking early, late or not at all. Their results varied, so I did some of my own trials. I expected best results from declutching late, once the braking sequence was well in hand but well before stalling it.

What I found was that I was a couple of metres better off leaving the bloody thing alone alltogether. Even dropping a couple of percent of my focus from the braking feedback / load loop cost me more than the little bit of drive from the almost-stalled engine.

I still don't do it though. I learned in the dirt, where a fairly high percentage of my brake work is emergency braking. It's just too hard to change habits as old as mine.

Although I'm making progress with the two-finger braking thing, on account of some good lessons from adverse effects of the BIG GRAB technique on the Buell.

[Banditbandit]

First the brake gently and squeeze it progressively and smoothly harder to avoid locking the front wheel.

In an emergency ??? I definitely don't gently squeeze .. I stand on everything ..

[slofox]

I find I chop successively down through the gears under hard braking...dunno why - just do it.

Slipper clutch helps with the lock-up problem...

[AllanB]

Darn where is SKIDMARK?

I mean he could brake from 160 in 4 metres .........