Braking: Part 2

This is the second of a two part series, where IAM examiner Jon Taylor looks at putting the theory of braking into practice. Bearing in mind the points made in the first part of this article, how is any human being ever going to be able to calculate just how much braking can be done at a given time?

Well, we come back to the good old practice, practice, practice bit again!

But if you’ve just practised at one speed on one machine in a flat car park, that’s not going to equip you very well for the real world out there now is it? The only way you can do that, is to practise braking in many different situations, such as when cornering. Don’t dream of doing this on a busy road, but on a racetrack or a private road somewhere this can be most effective. The important thing is to start very gradually, building up as you go, as you become aware of what the machine wants to do. Racers do this all the time, it’s called practice sessions.

Exactly the same rules apply of starting the braking with sufficient pressure to induce weight transference (depending on bank angle of course) but not enough to induce a slide, and then gradually increasing the pressure. What does the machine do? It tries to stand up and go straight out of the corner so additional steering has to be brought in to ensure the machine holds its line. This can all be practised at leisure and the skill is then registered into the subconscious for that day which hopefully will never come when you’re coming round a bend and there’s an accident ahead of you that has blocked the road. You have no option but to brake in the middle of the bend, but all that practicing you did earlier will be brought into play, and you will hopefully be able to stop, but even if not, you will have reduced your speed sufficiently to greatly increase your chances of walking away.

So get out there and try all the different scenarios you can think of. Enlist the help of a pillion, perhaps your riding pal will go on the back of you while you try and then you can do the same for them. You’ll both be surprised at how quickly you can stop two-up but I guarantee you’ll both also be surprised at just how much weight the rider’s arms take when you have not only your weight but the weight of the pillion behind you as well, something you don’t always expect until you actually start doing it in earnest.

Locking the wheels

Following on from this, if you feel confident about it and your bike allows you to, try practising locking the wheels. Start with the rear, find a good level surface away from any other traffic and in a straight line, travelling at about 50 kph/31 mph lock the rear wheel and keep it locked until the machine comes to a complete halt using your butt to control the vehicle if it slides one way or the other.

This may take several attempts, but once learnt this experience will help you to control a rear wheel slide in an emergency situation without you having to consciously think about it.

Likewise, if you feel able, do the same with the front but with a few important differences. To hold the front wheel locked will almost certainly result in a total loss of control, so instead this time raise the speed to about 70 kph/43 mph and try momentarily grabbing at the front brake (something you would only do for this exercise) and then releasing immediately. A sort of cadence braking action. With the higher speed will come more gyroscopic stability from the rear wheel so that when you momentarily lock the front wheel it will have less effect on the balance of the machine.

Grabbing at the brake, whilst being exactly the opposite of what we would normally wish to do, is the most effective way of locking a wheel due to effective weight transfer not having had the opportunity to have taken place

What you are trying to do here is identify what a locked front wheel feels like. If it is an emergency situation your brain will not have enough time to learn something new, but if it has experienced it before, it should quickly remember what it is and be able to correct it almost immediately. In normal day to day riding though, hopefully the limits of your braking will not be tested, but the benefits of the practice will still be there. Smooth application at first, building up to firm pressure in the middle and then tapering off as you either apply acceleration, or come to a complete halt will ensure that any pillion riders will have an easy time and that the ride will flow more smoothly.

Controls

Another aspect of getting the best out of your brakes is how your controls are adjusted. No two people are exactly alike and things like the length of the fingers, size of the hand and muscle strength vary enormously from person to person. However, nearly all large machines nowadays have the facility to adjust the span of the front and rear brakes so making use of this can improve your braking performance overall.

A front brake lever exerts most force when it is parallel to the handlebar, so ideally you should adjust your front brake lever so that the brakes are fully applied when the lever is about 2cm from the throttle. This way you’ll be exerting maximum braking force and thereby control just at the point you need it. With the rear brake you should aim to be able to apply it without having need to either remove the foot from the footrest or having to rotate the foot through a large angle. Again, roughly 1 – 2cm below the sole of the foot should be fine to prevent unintentional application of the brake on bumpy roads but at the same time exerting maximum control over it when in use.

Two types of braking

Also, don’t forget that there are two types of braking, use of the brakes as described above but also engine braking. Follow a rider who you know to be very good and I’ll bet that one of the things that impresses you about their ride is that they hardly ever seem to be using the brakes.

Why? Because their planning and observations are at such a level that they have already responded to what is happening ahead and gently rolled off the throttle early enough to have achieved any SLIGHT reduction in speed necessary by means of engine braking.

However, don’t be lulled into thinking that using the gearbox as a brake per se is what is needed; doing this will be more likely to make your ride even less smooth than before. It is quite common for riders who have not yet fully developed their technique to try to emulate the smoothest riders by mistakenly using excessive engine braking rather than having following riders see them showing a brake light to the rear.

Where engine braking can however be used quite effectively is when travelling down steep hills

At this time using a lower gear will just hold the machine back from actually being accelerated down the hill by the force of gravity; then the brakes can be used just to get rid of a little more speed prior to bends or other hazards that may be encountered.

On very slippery surfaces you may find that the rear brake only gives better control than even engine braking depending on your particular machine. Bikes with a lot of engine braking (large capacity singles and twins, particularly if they have fuel injection) can quite easily break traction at the rear in such conditions just by closure of the throttle, sometimes causing the rider to panic when the rear of the machine steps out without them even touching the rear brake. In these circumstances it can sometimes be best to de-clutch and very lightly apply the rear brake, releasing if the wheel starts to slide again and then gently re-applying the pressure, even better if antilock brakes are fitted as these will do the work for you. The reason for this is that you have a finer and more immediate control over the pressure to the rear brake than you do by controlling the twist grip and this will be even more pronounced with machines fitted with shaft drives due to the torque effect of the drive shaft and what is commonly referred to as shaft-jacking. (The effect of the rear of the machine rising as the power is applied and vice versa)

What they are actually doing is covering up their lack of forward observation and planning with excessive engine braking instead of tackling the problem directly.

Anti-lock brakes or ABS

One type of braking system that we haven’t covered yet is anti-lock brakes or ABS as it is commonly known. This is usually an electro-mechanical system that senses when a wheel is about to lock-up and momentarily reduces the pressure to that brake until grip is regained and then re-applies the braking pressure, all in a fraction of a second and far faster than the rider would ever be able to do.

The real benefit of anti-lock brakes is that they give a rider the confidence to brake hard if the situation requires it without the fear that the wheel might lock-up and the rider lose control

In a study in America it was found that a large number of riders, in an emergency situation, would brake excessively hard with the rear brake and not use or use very lightly the front brake for fear of losing control.

Now as we’ve seen earlier, it is the front brake that does most of the stopping when braking hard, and as we’ve also seen, the difference between reducing speed quickly but effectively and not doing so can literally be the difference between life and death. So if the rider has the confidence to squeeze the front brake lever hard, safe in the knowledge that the ABS system will save them, they are far more likely to use it to its full potential than if they are frightened of it through lack of experience or practice.

Don’t be fooled though into thinking that ABS will save you every time

The one large problem with ABS on most machines not fitted with the latest sport ABS is when that machine is banked over at any more than a few degrees. As we’ve seen earlier, ABS senses when a wheel has or is about to lock-up. If you’ve already got a reasonable bank angle on, that momentary locking-up will be enough to start the machine sliding sideways, and it doesn’t matter that the ABS has released the pressure momentarily, because now the wheel is sliding sideways it will not have fully achieved the speed of the rear wheel again and the sensor will still think it’s sliding and not re-apply the pressure. Result: the wheels slide out from under the machine and the rider loses control.

Rehearsing scenarios

At the beginning of this chapter we talked about how effective reduction in speed can have a dramatic effect on the outcome if the worst comes to the worst. However, very often in actual situations the wrong decision is taken at an early stage which leads to the situation becoming worse than it needs to be. Take for example that ever-present threat to the motorcyclist, the car pulling out from a side turning. If the rider hasn’t anticipated this happening by use of the other tools we’ve mentioned to avoid this situation in the first place, they may be faced with making a very quick decision based on the circumstances prevailing at the time. That is to say: do I brake hard and get rid of my speed, the thing that’s going to hurt you; or do I try to take avoiding action by effective use of counter-steering? If it’s the latter, the rider is now committed to a course of action that effectively precludes braking.

The laws of physics prevent a motorcycle from both braking very hard and swerving at the same time

This may be fine if the driver of the emerging car has actually seen you and stopped, but can you afford to take this chance? If they carry on moving you are likely to collide with them only in a slightly different position. If you’ve gone for the front and they carry on, the two of you meet on the other side of the road, if you decide to go for the rear, anticipating that they will carry on pulling out and they stop then you collide with the rear. But the really important concept to grasp here is that on both occasions you will impact with most or all of your original speed.

Summary

Once again it all comes down to a combination of the knowledge of the theory behind what is happening to your machine and practice in as many different conditions and scenarios as you can find. If you are fortunate enough to have ABS fitted to your bike, try it out. See what it can, but even more importantly what it can’t do. If the worst ever happens you may be very grateful you did, as it will help your brain come to a very quick decision about which course of action to take.

Hopefully, by using the rest of the bag of tools, your observations and control of speed will never allow you to get into these situations in the first place, but even the very best of riders have been caught out from time to time, so really work on those braking skills and give yourself the best possible chance. If the time ever comes, you will thank the day you carried out all that practicing, I assure you!

If by trying to swerve round the front of the car, it takes you into oncoming traffic then you need to add your speed to that of the oncoming traffic and the consequences don’t really need much thinking about.

The overwhelming first consideration in any of these situations must be to reduce your speed as quickly as possible whilst retaining control of your machine. Most other courses of action are a gamble on what the other road user may, or may not do

Remember, actually running through in your own mind potential scenarios like the ones mentioned here will prepare you mentally to make a quick decision as to your best course of action should that situation present itself in future. It’s almost like gaining the experience without actually having to go through it much in the same way as pilots do in flight simulators.