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 at motoDNA advanced rider training course’s.
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.
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.
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.
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?
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.
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.
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.
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.
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.
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.