Braking technique

[st247]

Newbie here, gonna jump in. The confusion comes when people say clutch and mean the clutch lever. Engaging the clutch lever ( pulling it in ) disengages the clutch. Disengaging the clutch lever ( letting it out )engages the clutch. All the technical manuals i've seen mean the actual clutch pressure plate and friction plate assembly when they use the term "clutch".

So BM are asking us to pull the lever in disengaging the clutch as soon as we start an emergency stop. This has a couple of consequences that people may not be aware of.

Whipping the clutch in as soon as you start braking is the most common cause of stalling the engine( from what i've seen ). Which may lead to a loss of control and it certainly limits your options if an escape route opens up!

Leaving the clutch engaged (lever out) untill your down to the last few mph has the effect of stabilising the bike, the rear wheel effectivley acts like an anchor pulling the bike back. This keep the engine turning ( giving you the escape option ) and prevents the back wheel from leaping about going over some of the minor imperfections we have on our roads.

Personally i cant see any advantage to disengaging the clutch as i start to brake. But the reality of it, is that in the case of an emergency stop the vast majority of us will just grab the brakes. Hence why we bought ABS equipped bikes.

 

[Pressurized]

All right, all right, I'll bite (and probably regret it)...

Putting aside the rest of your words as worthwhile addition to some of the arguments above, allowing riders to make an informed decision as to how they want to stop...

How do you come to this conclusion...

Whipping the clutch in as soon as you start braking is the most common cause of stalling the engine( from what i've seen ).

apart from what you've seen?

Why does pulling a clutch in cause an engine to stall?

Is it a two stroke thing?

 

[GSmonkey]

Leaving the clutch engaged (lever out) untill your down to the last few mph has the effect of stabilising the bike, the rear wheel effectivley acts like an anchor pulling the bike back.

Thats fine until the rear wheel comes off the ground, albeit with over a bump or whatever. At that point the effect of the road turning the wheel stops, the braking force applied will then stall the engine - causing the wheel to remain locked up when it hits the road again.

If you don't believe the effect of engine braking on the 1200, pull the clutch in, hit the kill switch then dump the clutch.

 

[Mzokk]

IMHO Pulling the clutch in an emergency braking situation you are way more likely to lock the rear wheel. May be fine if you have ABS but not in an NON-ABS bikes.

Non of my bikes have ABS.

 

[cookie]

Thats fine until the rear wheel comes off the ground, albeit with over a bump or whatever. At that point the effect of the road turning the wheel stops, the braking force applied will then stall the engine - causing the wheel to remain locked up when it hits the road again.

at which point the wheel will turn & bump start the engine unless you're going really slowly, in which case it won't matter. i'm not sure it matters much anyway.

this all sounds very theoretical to me. nothing like this has ever happened to me, and i've had a few er moments on bikes

in an emergency in the dry, i've got the front brake on so hard the back tyre is just rubbing the tarmac hard enough to stop it overtaking the front. that is where my concentration is going.
sometimes the bike will stall, it's never been something i've worried about

 

[st247]

I'lll try and answer as best i can without raising anyones blood pressure.

Pressurized When you pull in the clutch at the start of an emergency stop the rev's will still be quite high, As the clutch is pulled in and the throttle shut rapidly the rev's drop very fast, sometimes the revs will drop past the tickover point and the carburation/engine management won't be able to compensate quickly enough stalling the engine. Leaving the clutch out as you brake hard allows the engine speed to drop at a slower rate. Last year whilst doing a bit of instruction, 9/10 who stalled practicing an emergency stop did so because they pulled in the clutch to early. The other one didn't pull the clutch in at all

GS Monkey I agree that the GS has a huge amount of engine braking which is why i suggested what i did on my last post. IMO the rear wheel is less likley to leave the road surface if the clutch is still engaged and the wheel driving the engine. I agree with your point that the braking force may still stall the engine if it leaves the road but i do wonder what effect the ABS would have on this? would it really allow the wheel to lock? in contact with the road or not?

All of this is of course open to debate.

There's a good deal more info on this in Roadcraft or Keith Codes Twist of the Wrist Two.

 

[Pressurized]

Pressurized When you pull in the clutch at the start of an emergency stop the rev's will still be quite high, As the clutch is pulled in and the throttle shut rapidly the rev's drop very fast, sometimes the revs will drop past the tickover point and the carburation/engine management won't be able to compensate quickly enough stalling the engine. Leaving the clutch out as you brake hard allows the engine speed to drop at a slower rate. Last year whilst doing a bit of instruction, 9/10 who stalled practicing an emergency stop did so because they pulled in the clutch to early. The other one didn't pull the clutch in at all

Sorry, don't buy it.

That's not to say I would or wouldn't pull the clutch in; before BMW's insert I wouldn't have, now - after quite a bit of thought and assistance from people on this forum - I may decide differently (hopefully before my next emergency stop situation which, thankfully, are quite rare).

 

[GrinningGSer]

The reason for pulling the lever in on an emergency stop is that with the extreme braking forces and rapid decelleration it is highly likely that the engine will stall. This EXTRA braking effort from a stalled engine will likely lock the rear wheel thus introducing a possible loss of control. The theory is therefore that the clutch is disengaged and braking is done using the brakes alone, which after all are sufficiently powerful to lock both wheels.

GS Monkey your explanation confirms my thoughts. ABS on the rear wheel is rendered useless IF you stall the engine and lock the wheel. (Trust me -if any of you havent tried turning the ignition off while riding the GS1200- try it in safe conditions and you will be shocked by the locked rear wheel !)

So maybe ABS works best with a free wheeling bike ??

And do you do it differently if you havent got ABS ??

 

[Pressurized]

So maybe ABS works best with a free wheeling bike ??

I think, probably, yes. This thread has helped changed my mind.

I hope you got as much out of it as I did!!!

There's been a bit of BS along the way, some of it mine.

When I can get a bit of dry road, I think it's time to put this theory to the test. After that, maybe my instinct will be to disengage the clutch in an emergency stop and let the bike do the braking.