Emergency Braking – Facts vs Myths

08th Mar 2016 Rider Safety, Technique

There is a lot of misunderstanding surrounding correct emergency braking technique. Perhaps it’s the fact that most riders are tentative with the front brake due to the obvious risk of locking the front wheel. Certainly that’s the body language we see before our emergency braking drills at motoDNA. However, empowered and confident riders emerge post drill after mastering proficient emergency braking.

Fact: Only 15% of Level 1 students can perform an effective emergency stop before completing a motoDNA training course.

Bike Balance

Some understanding of bike balance is useful for good riding performance including emergency braking. Consider that weight distribution between front and rear tyres is constantly changing as you corner, accelerate and brake. When you apply the front brake, the bike pitches forward (see diagram below) applying vertical load to the front tyre. When you release the brakes, weight comes off the front tyre and starts transferring to the rear, increasing as you throttle on.

Pitch Roll Yaw

The key is to load the tyre progressively to build pressure on the contact patch. This progressiveness should apply to your braking, acceleration and cornering. Problems arise when a rider overloads the tyre by grabbing the brake, or throttle, rather than applying the input smoothly and gradually.

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 co-efficient of friction. Try sliding an eraser lightly across your kitchen table. Now try the same thing pushing down hard on the eraser. Notice the increase in grip with the extra vertical force?

The same logic applies when you use the front 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 contact patch pressure multiplies due to the load transfer when braking.

To understand, simply push your 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.

Front Brake 

Nothing will slow you down faster than the front brake. Have a look at the photo below showing a motoDNA student executing an emergency stop. How much is engine braking or the rear brake contributing to slowing down the bike?

Women-Emergency-Braking

Even if the rear tire is on the ground, there will be very little load on that tire as most of the weight has transferred to the front. Excessive engine braking or rear brake is most likely to lock the rear.

Rear Brake

The rear brake contributes little braking power on most bikes (except long and low cruisers) has less feel than the front brake and is normally reserved for mid corner fine adjustments or to stabilise the bike.

The rear brake is also likely to lock up in an emergency stop adding another problem of trying to control a skidding rear wheel. Ask yourself why bother with the rear brake if it’s easy to lock up and contributes little braking performance?

Fact: 20% of motoDNA students lock the rear brake during their first emergency braking practice drill.

Clutch

If the rider has not throttled off during emergency braking, the bike will still drive forward against the brakes reducing the braking effectiveness.

Fact: 15% of motoDNA students still have some level of throttle on during their first emergency braking practice drill. In a real emergency this throttle % is likely to rise.

Braking

Even worse, the bike will pitch less, which means less vertical load on the front tyre reducing the available grip. At motoDNA we teach students to pull the clutch in immediately when they apply the front brake, which negates this common issue.

Cover Brakes

In an emergency you need to react quickly and having your fingers on your front brake lever in high-risk environments reduces time trying to find it when you are in a panic. Practise your technique of shutting the throttle and applying the front brake. Two fingers should be off the throttle going for the brake lever as you close the throttle. This can save precious fractions of a second in an emergency.

Shifting

Obviously in an emergency the primary goal with is to stop as quickly as possible. However what about the distracted cager behind texting on their phone? Make sure when you have stopped that you are in first gear and ready to get out of the way from any 4-wheeled chaos that might come your way, down your exit route.

Engine Braking

Nothing will slow you down faster than the front brake. Excessive engine braking can lock the rear wheel if you don’t match the engine revs to the road speed. As long as the clutch lever is pulled in, engine braking won’t be a problem.

Ergonomics

At motoDNA we see plenty of examples of the front brake lever not properly adjusted or simply too far away from the rider’s hand. 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. Ensure your front brake lever is perfectly adjusted.

Body Position

You should be holding on to your bike through your legs with your body up against the tank and arms slightly bent. Ensure you keep your head-up, looking ahead to maintain good balance and vision.

Road Surface 

Other factors such as road surface characteristics and further 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-lock 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 grip levels, anti lock brakes are simply one of the best safety additions for riding a motorcycle.

Reaction Time

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 travelled 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 each! Higher speed equals more distance travelled. Consider at 100 km/h one seconds equates to nearly 30 meters! That’s almost 60 metres before you even start braking. Ensure your speed is appropriate.

The Technique

Close the throttle and initiate the front brake.

Quickly apply initial lever pressure; this will make the bike pitch forward transferring vertical load onto the front tyre.

Then squeeze the brake lever progressively, until you come to a complete stop.

At the same time you will pull in the clutch, tapping down the gears until you are in first gear ready to escape from following 4 wheel hazards.

Never snatch at the brakes as this can cause the tyre to skid.

The road surface is not always perfect, always anticipate that the front tyre may lock and be ready to release and quickly reapply the brakes.

Attitude

As a rider, emergency braking should be intuitive. Like any other motorcycle skill, you should first seek training with the correct technique, then practice regularly, then top up with regular training to improve your riding and keep those skills sharp. Beware of the Internet experts; like any information gained online the quality is only as good as the credibility of the author.

The motoDNA Riders Academy knowledge base comes from over 100 years of combined Coach knowledge; some of our trainers are former MotoGP racers and our data comes from training thousands of motorcycle riders each year.

Book Here for your next motoDNA Advanced Rider Training course