Emergency braking: Clutch or de-clutch?

[Tunahunter]

Some interesting comments here

http://bettermotorcycling.wordpress....-or-de-clutch/

[ac3_snow]

well wotdoyaknow! very interesting read. I was a subscriber to the "leave the clutch engaged untill the last minute" method. Made sense to me, for both bikes and cages.
Be interesting to know if the same is true with cars..

[Banditbandit]

Far Out!!! So I've been doing it right

That's not a conscious decision. In an emergency I generally grab everything and stand on everything. I think it's an addrenalin reaction.

However, after some thougth, I'm inclined to think that pulling in the clutch lever means you're also puling the brake lever harder ... Think about it - right hand, squeezing brake lever, left hand no action - that's likely to mean the right hand is not applying as much pressure as it might ...

If you grab both levers and squeeze, you're more likely to be applying maximum pressure through the right hand to the front brake lever ... and stopping faster

[CookMySock]

In an emergency, I don't think you should be pissing around with the clutch. 100% brain power to the task at hand, and stand the fucker on its nose and concentrate!

Also I'd like to suggest the few percent difference they got could easily be put down to other factors.

I learned huge amounts about braking at a track day. It's insane how quick your bike can stop, and how all the wriggly scary shit it does under maximum braking can safely (in a straight line in the dry) be ignored, and I suggest THAT is the best way to learn how to pull up in the shortest possible space. Clutch - irrelevant.

edit: There is also the situation where the final drive will give a loud chatter-chatter-chatter when the rear starts to lock. I find this very valuable indeed when trying to figure out how much braking pressure to apply.

[p.dath]

Check out my blog on emergency braking. I discuss the most common methods taught, which tend to vary based on where you live in the world.
http://www.kiwibiker.co.nz/forums/en...rgency-Braking

My preference is to immediately engage the clutch.

I help out at NASS, and I can tell you a lot of riders have a problem with closing the throttle during emergency braking. If you immediately close the clutch then this is not an issue. If you delay doing this then you will drive the engine against the brakes - and I guarantee you that your stopping distance will be much greater in this case.

The emergency braking control over a motorcycle should not be using your cognitive brain power. It should be something you have learned to do automatically. And you can achieve this by simply practising emergency braking again and again till it is automatic.

[p.dath]

Also I'd like to suggest the few percent difference they got could easily be put down to other factors.

I can tell you with the new riders we help that it often halves (yes, halves) their stopping distance by simply engaging the clutch immediately.

[cheesemethod]

I can tell you with the new riders we help that it often halves (yes, halves) their stopping distance by simply engaging the clutch immediately.

I remember when I was starting at NASS I found exactally the same thing, but that is also because I was using about 20% of the braking that I had available.

Personally I prefer only touching the clutch when I'm almost stopped. I've always felt that pulling the clutch in makes the bike feel unstable and makes it easier to lock up the rear. Distance wise for me it makes stuff all of a difference, so I'd rather be in control and ready to get on the power - stopping might not be your only option in hazard avoidance.

[Usarka]

+1 for not even thinking about it, do what comes natural and concentrate on braking.

I can tell you with the new riders we help that it often halves (yes, halves) their stopping distance by simply engaging the clutch immediately.

Probably because its the natural thing to do, and therefore removes the extra cognitive processing required. Ie. if "halves the distance" is true it'll be down to brain rather than braking.

[Headbanger]

I engage the clutch just before the stall, but most of the time I'm back on the power to control the bike and getting myself into a safe line of travel.

Coming from many years of dirt bikes, I'll stand on the brakes, slide the bike where I want her, and crank the fucker back open.

Played havoc on the gearbox when I rode a Harley

[schrodingers cat]

First the brake.
Everything else is seconday.
It takes approx 0.15 - 0.2 sec for the rear to unload at all


First the brake. HARD

[bogan]

I help out at NASS, and I can tell you a lot of riders have a problem with closing the throttle during emergency braking. If you immediately close the clutch then this is not an issue. If you delay doing this then you will drive the engine against the brakes - and I guarantee you that your stopping distance will be much greater in this case.

I always position my levers/hands such that to grab a handful of brake is to be off the throttle, thought that was how it was sposed to be done, is this not the case?

The emergency braking control over a motorcycle should not be using your cognitive brain power. It should be something you have learned to do automatically. And you can achieve this by simply practising emergency braking again and again till it is automatic.

In either case the rear will likely skid/skip anyway so do whatever comes naturally, for me it's to grab the clutch too, but I learnt that from off-road too.

[javawocky]

Break heard and gear down and let engine breaking help you out.

If the back wheel locks you will instantly know by the stopped engine an can let of the rear break to regain control.

If its not engage you will only know the rear is locked up when it starts coming around, you let go the rear break and the locked rear snatches traction and causes the bike to become unstable.

My 2c

ps. a slipper clutch is a great help here as it limits rear wheel torque.

[CookMySock]

If the back wheel locks you will instantly know by the stopped engine an can let of the rear break to regain control.

This advice has helped me out a few times. I've never stepped the tail out from over-braking it, but the chatter-chatter-chatter from the final drive is very clear warning to "please release pressure from the rear brake" or else

[LBD]

Maybe we should clarify the defination of engage and disengage the clutch....pulling the clutch lever DISENGAGES the clutch....


"On most motorcycles the clutch is operated by the clutch lever located on the left handlebar. No pressure on the lever means that the clutch plates are engaged (driving), while pulling the lever back towards the rider will disengage the clutch plates through cable or hydraulic actuation, allowing the rider to shift gears or coast."

[p.dath]

Personally I prefer only touching the clutch when I'm almost stopped. I've always felt that pulling the clutch in makes the bike feel unstable and makes it easier to lock up the rear.

You should not be concerned about locking up the rear under emergency braking. If you are braking hard the rear often locks up, because the weight comes of the rear tyre. As the rear tyre has less and less traction with the ground it becomes easier and easier to lock up. At this point the rear brake has pretty much no input. Hence it makes no difference weather it locks up.

Likewise pulling the clutch in should not have an impact on bike stability while emergency braking. Pulling the clutch in removes power from the rear wheel. The rear wheel has little weight on it, and little traction, and hence little drive. And ideally, you want the rear wheel to have no drive - otherwise it is fighting the brake.

Locking up the front affects bike stability. Commencing emergency braking while not upright and balanced affects bike stability. But I can't see the how the clutch should affect it once the weight is transferred onto the front wheel.

I always position my levers/hands such that to grab a handful of brake is to be off the throttle, thought that was how it was sposed to be done, is this not the case?

In either case the rear will likely skid/skip anyway so do whatever comes naturally, for me it's to grab the clutch too, but I learnt that from off-road too.

People are of all different heights, with different arm lengths, and different size hands. A lot of bikes simply can't be adjusted to achieve this. And even then, I'm not sure that is a good idea, as it makes learning to blip and brake while changing down difficult. You really (for a road bike) should be able to operate both the throttle and the front brake at the same time, as opposed to either or. But that is my personal opinion, and others will think differently.

The rear will not slip "out" under emergency braking if you commence emergency braking while upright on a flat service. It will simply slide in a straight line. Done it many times in practice. Many times. Once again, a rear wheel lock up/slide under emergency braking is not an issue - and is in fact likely if you are braking hard - because the weight rapidly transfers to the front wheel. No weight on the back wheel means very little traction. Consider the case when the rear wheel is completely off the ground ... if you have the rear brake engaged the rear wheel should be 100% locked up.

Break heard and gear down and let engine breaking help you out.

If the back wheel locks you will instantly know by the stopped engine an can let of the rear break to regain control.

If its not engage you will only know the rear is locked up when it starts coming around, you let go the rear break and the locked rear snatches traction and causes the bike to become unstable.

My 2c

ps. a slipper clutch is a great help here as it limits rear wheel torque.

There are a lot of schools of thoughts on this one. Personally, I am convinced that road bikes with disc brakes can supply greatly more braking effort that engine braking. And if the disc braking provide more braking force than engine braking, then the engine is guaranteed to provide driving force against the brakes making the scenario worse. Basically it's a personal decision for a riders. Brakes are designed to remove energy from the system. Engines are designed to add energy to the system.

If you are emergency braking to a complete halt who cares about the rear wheel. If you are "brake and escaping" then you don't have to worry about the rear wheel until you want to drive out again, and even then nothing much is going to happen until weight returns to being on the rear wheel again - which is likely to stop a lock up anyway. The whole issue self resolves a lot of the time.


A slipper clutch saves you against the disaster of changing down and not having the revs high enough (usually because you got the blip wrong), which would normally result in a rear wheel lock up. It's an interesting thought you raise. My thoughts are that if you use the method of immediately pulling in the clutch then a slipper clutch will do nothing. If you leave the bike in gear and simply close the throttle then the engine RPM will be held by the rear wheel, and have no impact. If you attempt a rapid down change with no blip then it might help you. But that's a lot of "ifs" and "buts".

My 2 cents.