motoDNA: Emergency Braking Techniques

05/19/2014 @ 6:10 pm, by Mark McVeigh8 COMMENTS

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Nothing causes as much confusion or trepidation in riders as emergency braking. How hard can I brake? Will the front wheel lock? Will I go over the handlebars? How far can I lean over on the brakes?

As a Motorcycle Instructor I am continually amazed at how many of our students, who have generally had some training and are licensed, come to us with inadequate braking skills. It’s super important to understand and regularly practice emergency braking on your bike. Normally I recommend a quiet car park with a slight up-hill.

To understand braking we must first understand grip. The main contributor to grip is the weight or load on each tire. The ratio between the maximum possible grip and the vertical load is called the coefficient of friction (μ). To understand this, slide an eraser across your kitchen table. Now try the same thing pushing down hard on the eraser.

This same thing happens when you brake on a motorcycle. The bike pitches forward transferring weight onto the front wheel, increasing front tire grip. More so with sports bikes, tall with short wheelbase compared to cruisers, which are long and low.

Also to consider is the significant grip increase experienced as the front tire’s contact patch pressure multiplies, due to the load transfer while braking.

To understand this simply push a tire with your hand and see how it flattens out. This is happening between the tire and the road as weight transfers to the front tire, increasing the contact patch and grip as you brake.

Also, as the brake is applied, torque is transferred through the wheel to the tire contact patch, which creates a horizontal force at the road surface. The road pushes back on the tire, and equally the tire pushes forward on the road. You can thank Newton for this mechanical grip; as for each force there is an equal and opposing force.

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On a motorcycle, the major braking power comes from the front. Consider how much power the rear brake contributes to a sports bike when the rear wheel can be in the air. Zero.

Other bikes like cruisers don’t pitch as much when a rider is on the brakes,  and thus the rear wheel will not come off the ground. Thus the rear brake has some braking performance. However the lion’s share remains with the front brake.

The majority of motoDNA students will lock the rear brake in initial emergency braking drills. This can put the machine out of control and the rider will be required to regulate the rear brake to regain control. Why bother with the rear brake if it’s easy to lock up and contributes little braking performance?

It depends on your bike. Good training and practice is the best way to understand your braking performance, your own reaction times, and improve your skill.

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Shifting: Obviously in an emergency the primary goal with is to stop as quickly as possible. However what about the distracted car driver who is texting on their phone? Make sure when you have stopped that you are in first gear and ready to get out of the way of any four-wheeled chaos that might come your way.

Clutch Use: Nothing will slow you down faster than the front brake. Make sure you get the clutch in nice and early. Another good reason for whipping the clutch in is the tendency to keep on the throttle while in a state of panic. I regularly reassure guilty motoDNA students that as long as the clutch is disengaged this doesn’t matter as the bike will not drive forward.

Trail Braking: Trail braking is a technique which is generally reserved for racers, used to slow the bike as quickly as possible from one speed (on the straight) to another (corner apex speed).

In applying this technique, a racer will approach a turn and at their braking marker apply full braking force, normally with the bike being upright. As they begin to turn in, they reduce brake pressure, easing off the brakes, decreasing or trailing the brake lever force as the bike lean angle increases until they get to the apex when they release the brake and apply the throttle.

Sounds easy enough in theory, but proper execution is complicated because it comes down to feel and remember these guys are doing this seamlessly, every lap on the limit! Trail braking is a handy skill to have and can be useful on the road in an emergency. Get training before you try this one.

Braking while Turning: When emergency braking you are asking a lot from the front tire. If you need to swerve, best to get off the brakes and on them again. Again this is a highly skilled maneuver, get training and practice.

Ergonomics: I have seen plenty of examples of the front brake lever not properly adjusted or simply too far away from the rider’s hands. This means the rider has to stretch to reach the lever delaying the braking process. This is especially important for women who generally have smaller hands. Make sure your front brake lever is perfect.

Road Surface: Other factors such as road surface characteristics and other elements between the road and the tire such as water, gravel and oil play an important part in braking efficiency. In the real world it’s a big ask to emergency brake on these surfaces. Experience, skill or ABS will define your outcome. Improve the first two with training.

Anti-Locking Brakes: Conveniently following road surface considerations we mention anti-lock brakes. Its questionable whether anti-lock brakes can out perform a skilled rider. However on the road, with the unknowns in grip levels, anti-lock brakes are simply one of the best safety additions for riding a motorcycle.

Real World Thoughts: In the real world you don’t know when you will need to emergency brake. Thus, your total stopping distance will include a couple of extra elements such as perception and reaction times.

Perception time is the time taken to realize you need to react to a potential hazard. Reaction time equates to the distance traveled from the time you become aware of a hazard until you apply the brakes. Perception and reaction times can vary with age and are typically 1-2 seconds.

Higher speed equals more distance traveled. Consider at 60 mph one seconds equates to nearly 100 feet! That’s almost 200 feet before you even start braking!

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It’s possible to lock the front tire by grabbing the brake lever too quickly, before the bike has had time to pitch. To avoid this, first get off the throttle and initiate braking, this causes the bike to pitch transferring weight and grip to the front tire, then squeeze the front lever progressively until you come to a stop.

At the same time you will whip in the clutch, tapping down the gears until you are in first gear ready to escape from following four-wheel hazards, all this while applying light pressure on the rear brake.

It’s best to practice using the front brake and clutch to begin with, then introduce the rear brake and downshifts. Emergency braking is a must have skill that motorcyclists should regularly practice.

However, what about preventing the need to emergency brake in the first place?
Mark McVeigh is a former international motorcycle road racer and MotoGP engineer who now works as a moto-journalist and development rider.

He currently is also the Director of Coaching at the motoDNA Motorcycle Academy. Read more of Mark’s work on the motoDNA blog, and follow motoDNA on Twitter and Facebook.

Comment:

  1. crshnbrn says:

    What, you’re not going to cover backing-it-in?

  2. Fanabart says:

    Quote : It’s best to practice using the front brake and clutch to begin with, then introduce the rear brake and downshifts. Emergency braking is a must have skill that motorcyclists should regularly practice.

    It though it was best to start with the rear brake (gently) and a fraction later the front brake. This would make the rear suspension to go in a bit and have less pitch effect when the front brake is applied with more power.

  3. Bruce says:

    I’ll just add, be aware of who/what is behind you, particularly if you are on a group ride. If your braking skills exceed those of the rider behind you, you may find yourself taken out from behind in the event you need to brake hard.

  4. Walter says:

    Have you tried the KTM1190 with MSC (Motorcycle Stability Control)? I’m not saying it’s a substitute for practicing skills (especially since it will be a while before the feature is widely available), but in emergency situations it sure seems to provide a safety net.

    And Bruce added a very important consideration.

  5. Sean says:

    The best emergency braking method is very different, depending on whether you have ABS. Assuming that you have modern ABS with rear-wheel-lift control, the best method is to instantly crush that front lever in a grip of death, whilst simultaneously pulling in the clutch and stomping on that rear brake.

  6. colin says:

    Wouldn’t clutching in n therefore free wheeling make it easier to lock up the rear n lose control?

  7. Mars says:

    Keith Code. Read it.

    A motorcycle tire has 100% traction available at al ltimes. However much that is.

    You can use that 100% any way you want.

    It is available principally for two things:

    1) Stopping
    2) Turning

    If you do both at once, you reduce the amount available to each function by the amount used for the other.

    If you are hot and wide in a turn, it is often best to use your traction for turning rather than braking, if non-intuitive.

    Every time I have run off the road wide on a turn it was because I was trying to brake rather than turn.

    For the street, I mostly try to brake early and upright, and then let off and do my turn.

    Of course, emergencies change everything, and we often have to balance the two functions.

    Herein lies the art of riding and herein lies the benefit of ABS. It takes away some of the thining and skill requirements at just the time you need them most.

    I am a purist, but to me, ABS saves lives. I don’t have in on my NInja 1000 though, so it’s old school and i takes my chances.

    I like this article.

    Thanks!!!!

  8. Alclab says:

    @Mars:

    Great comment! indeed I read it and agree with what you say. Practice is Key of course, and taking some professional course in a closed circuit can really help, specially if they have (and they should!) an emergency braking drill.

    I took a course personally when learning and the skills learnt from emergency braking on a Non-ABS bike has saved my life and my bike from some very dangerous situations! Knowing how to use BOTH brakes, control the rear wheel if it locks, braking on wet or slippery roads, and specially emergency braking on turns is extremely important!

    Ride safe, cheers!