Braking technique

[NeverRodeBefore]

Newbie's perspective

My insturctors taught me (I had a few different ones) this summer, and they said that under emergency stops, it doesn't matter if you stall the engine (thereby the clutch must still be connected to the wheels and engine). If you stall, simply pull the clutch lever in, restart the engine, move down to first gear, check your right then left shoulders and pull into the curb.

I never actually stalled the motor, and was quite quick in my practice runs... despite the first time when I ran past the instructor on the cbt as he held his hand up... I thought he was going to drop it when he wanted me to stop...

My landrover developes a hell of a lot of engine braking when it's fully on tune, they were famous for it really, take you foot of the gas and she'll all but stop... that's why the brakes on the old ladies were so rubbish

 

[NeverRodeBefore]

Just another thought!

My dad tried my R1200GS out on my works carpark not long after I got it, and at one point as he was pootling round, he shut the throttle off as he was approaching a bend, and the rear wheel effectivley stopped in the loose gravel at the edge of the carpark!

 

[Pressurized]

Nooooo a disengaged clutch means that the lever IS being pulled

Double negatives and you Nearly had me confused there

Sorry, but I think you're wrong.

That said, here are one site that agrees with me and two that don't.


http://www.championsidecars.com/reverse/RevInstr4v2.pdf

http://eesc.orst.edu/agcomwebfile/EdMat/4-H42471.pdf

http://www.edmunds.com/ownership/techcenter/articles/43837/article.html


Pulling the clutch lever in to assist braking is plainly wrong. To do it in an emergency stop even more so as it gives you another thing to do when you're hands are already full, as it were.

I'll contact BMW tomorrow and see if someone there can tell me what they mean by disengaging the clutch.

 

[GrinningGSer]

Pressurized- The one that agrees with you is wrong and the two that disagree with you are right.....
Disengaged clutch = no pull on lever =no engine power to rear wheel ??

If we wait a bit someone else here will confirm/deny this

 

[Tarka]

Pressurized`s belief is wrong.

The clutch is normally engaged....IE it is engaged until you pull in the handlebar lever ( or press the pedal in a car ).
Pulling the handlebar lever in (or depressing the car pedal) disengages the clutch.
Releasing either of them engages the clutch.


I think some of the confusion is due to 'bikespeak' when people say things like 'Let the clutch out rapidly and the bike wheelies'.
They are referring to the action of letting the clutch LEVER out...which is letting the CLUTCH in...'engaging' it.

 

[adamski49]

In an emergency stop situation pulling the clutch in makes sense to me because:

1. At tickover in top gear my Fazer would be doing about 15mph so once you've braked below this speed the engine is pushing against the brakes.

2. In the rush to grab the front brake you can't be sure you've fully rolled off the throttle and this would increase the speed at which the engine is pushing against the brakes.

This applies to an emergency stop only. If it's a rapid stop I'd be knocking down the gears and releasing the clutch between each one just to be in the right gear to accelerate away again if the opportunity arises.

The argument that brake pads are cheaper than gearboxes falls on deaf ears as I've only ever had to replace brake pads, never a gearbox.

Adam

 

[Mzokk]

what a lot o pish. Who comes up with these ideas.

That sums it up for me too. Also recon in an emergency situation you are much less likely to lock the rear if the clutch is out and the engine is driving.

Also I've done a lot of track riding and the engine DOES brake the rear wheel when you are changing down and braking for a corner. On the track I rarely use the rear brake and often the rear wheel is locking and trying to overtake the front........hence slipper clutches.

 

[GrinningGSer]

Important correction:
Disengaged clutch = no pull on lever =no engine power to rear wheel
should read
Disengaged clutch = pull on lever =no engine power to rear wheel

 

[GSmonkey]

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.

That was the theory for the test when I took mine. It does seem reasonable.

 

[Pressurized]

Important correction:
Disengaged clutch = no pull on lever =no engine power to rear wheel
should read
Disengaged clutch = pull on lever =no engine power to rear wheel

Confusing isn't it!!!

GSMonkey may have a point, though. While I'm not sure about extreme braking and deceleration in themselves stalling the engine, the engine could stall if the rear wheel comes off the ground. A stalled engine would seriously challenge grip when the wheel comes back down and the ABS wouldn't be able to do a thing about it.

 

[dave wilcock]

below 35 mph a hand full off front and stamp of rear stops pretty dam quick, my reaction above that is hand full of front use clutch to stamp down at least 2 gears release clutch(lever)and stamp on the rear, clutch in just before stop/stall.
pull in the clutch when breaking from speed helps to lock the rear wheel-skid- loose control? with the front brake on hard the weight is transfered to the front tyre ,less weight on rear means less preasure on rear brake locks up wheel easier . a skid is not in control.

 

[GSmonkey]

. While I'm not sure about extreme braking and deceleration in themselves stalling the engine, the engine could stall if the rear wheel comes off the ground.

Sorry, didn't express myself very well. Yes you're correct - it is the significant tranfer of weight to the front which leaves the rear wheel more susceptible to coming off the ground. Under this circumstance the applied brakes will stall the engine....the wheel will then continue to skid unless the rider disengages the clutch. Hence you should disengage the clutch straight away.

 

[Pressurized]

My belief in what an engaged clutch is has been shaken. If I'm wrong in that, my belief in how to best do emergency stops has also been shaken.

One thing that does stick out in the way the manual insert's been written is that it's been very carefully done. It's like engineers watched over by company lawyers have written it. Corporate liability is being minimised and it is disturbing.

I'm still intending to chat to someone at their HQ tomorrow and, if it turns out that they want you to pull the clutch in when minimising stopping distance, I'll want to know why.

I've also got an invite to get my brakes checked over free of charge (provided I do it before the end of February). That's a long ride to Chelmsford for me; the coffee had better be free too!

 

[Micky]

One thing that does stick out in the way the manual insert's been written is that it's been very carefully done. It's like engineers watched over by company lawyers have written it. Corporate liability is being minimised and it is disturbing.

That's ABS for ya :helmet

 

[HR0]

Like you are going to think all this in an emergency..........
just grab a handful and hope for the best.(the front and rear are linked any way aren't they

but Having just taken IAM observed rides (they don't call them lessons) one should be riding in a position and observing so that one doesn't get into the scenario of having to emergency brake.

my 2 penny worth is

engaged clutch is NOT driving the gear box (lever in)
thus
to disengage is lever out engine has drive to the gear box.

for what it is worth the IAM books says
"when Braking to a stop, use engine retardation for the initial phase then progressively apply brakes................. obviously not an emergency situation
H

 

[(RIP) Kaister]

engaged clutch is NOT driving the gear box (lever in)
thus
to disengage is lever out engine has drive to the gear box.

WRONG WRONG WRONG FFS !!

clutch engaged = driving

clutch dis-engaged = No drive

think of a dog-clutch - dogs engaged / dis-engaged

( its not rocket science )

in racing circles - brakes are for braking, gearbox for going faster - and never try to do ones job with the other

 

[Pukmeister]

in racing circles - brakes are for braking, gearbox for going faster - and never try to do ones job with the other

Couldn't agree more Phil. Throttle for go and brakes for slow. Engine braking is for smooth progressive riding, to stop properly when really necessary use the damned brake lever, thats why it is fitted FFS.

 

[Mouse]

Here's my 2p worth

I agree that you should pull the clutch in (ie disengage it ) when doing an emergency stop. But I don't think you should do it immediately - as stated already even emergency braking should be progressive not sudden. If you pull the clutch at the same time as starting to apply the brakes, the inital stopping power will be less, as the brakes are not being used to the full potential and yet you have lost the engine braking at the stage of the process when it is most effective.

My technique would be to start braking and then pull the clutch after say half a second once the brakes are working to their full potential.

I can definitely see that once the braking force is at full, having the engine try to turn the rear wheel (which should be all but locked in a true emergency stop) would be counterproductive.

 

[Micky]

Couldn't agree more Phil. Throttle for go and brakes for slow. Engine braking is for smooth progressive riding, to stop properly when really necessary use the damned brake lever, thats why it is fitted FFS.

Totally agree...

 

[Pressurized]

I checked with BMW UK about what they meant by disengaged clutch. They told me to check with my local dealer.

Cannon today told me, after a quick check in the workshop, that disengaged means clutch lever pulled in. So I was wrong.

They couldn't really say why at first but did think that the theory of back wheel lifting and locking up would be a good explanation.

And it turns out that in driving lessons today, they tell you to push the clutch pedal down immediately in an emergency stop.