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The Front Brake

It’s a brake how hard can that be!!!!  You’d be amazed, because it’s not about the braking effect it’s about all the other effects.  If I asked a new rider to learn how to brake for an emergency in a straight line they would do a pretty good job, but once you take into account what happens before and after your braking effort under normal circumstances, i.e. accelerating, braking , cornering , accelerating things get a whole lot more complicated.  I count three transitions there and four “sets” that you need to choreograph your way through smoothly.

 

The psychic effect

For instance did you know that the mere thought that you are about to start breaking is impactful on the wobbly bits!!!  See you have the expensive air pump churning out horsepower and you’re driving along on a constant and stable wave of acceleration when suddenly you decide you need to slow down before the next corner or you may well have a high speed parking problem.  So you think, you loosen your grip on the throttle and that guy Newton starts to mess with you again.

I mean how fair is that, you haven’t even touched the brake yet, but the moment you let go of that throttle you go into that whole wobbly transition thing.  You’re transitioning, from a stable acceleration “set” to a deceleration “set”.

So you start to get a feeling for how much is going on the moment you realise that just the mere thought of braking, that moment of preparation for it, you already start to move from a stable position to a wobbly one, all by rolling back on that twiddly bit.

That bugger Newton again

At that moment Newton’s Third law comes into play yet again.  As you move your fingers to the front brake lever and begin to squeeze it, Newton’s third goes ballistic and what was going on at the first level gets worse whilst other things come into play.

The bike pitches forward, the rear suspension’s compression from the drive being delivered by the chain eases and the back of the bike rises, pushed up by the rear spring.

Weight transfers to the front of the bike and the front suspension starts to compress. 

As you pull on the brake the front wheel starts to act against the road and the rotating force, that the brakes are trying to stop, is transferred into the forks, trying to pull them over the front wheel.

This force is applied as if you were holding the lower legs of your front forks whilst sitting in front of the bike facing it and trying to force the bike up over your head.

The result is that the stanchions are forced against the fork legs and the stiction (friction that makes the forks reluctant to slide up and down) increases dramatically.  The net effect is your suspension, responsible for keeping your front tire gripping the road, works much less effectively.

This force is transferred and resisted by the headstock of the bike, that bit that attaches the forks to the frame and allows you to steer the bike.

Worse you now start to transfer your own weight onto the handle bars and brace yourself against that braking force that is trying to pitch you and the bike over the bars.  By now the front suspension and steering is becoming a solid fixed device, unable to turn in response to needs or soak up bumps or sudden changes in braking force, like you hauling harder on the lever as you panic or just as part of the natural increasing braking effort.

This means the bike’s front end will pitch forward and then get harder to pitch any more about the time you transfer all your weight to the bars and make the pitching force worse and that will force more traction on to the front tyre and ramp up the pitching force. 

By this time the back tyre is starting to struggle to keep any sort of contact with the road, which is a problem because all the effort going on up front means that unless everything is completely straight and you don’t wobble at all, not even slightly, the back of the bike is relying on the rear tyres grip to keep things moving in a straight line and within those rules that say its best when the rear of the bike isn’t leading the procession.  I’m guessing your would agree with that rule.

Worse as you start to wobble and the back gets out of line, because the front is locked up solid (No I don’t mean the front brake I mean the steering and suspension) things start to get interesting really fast, the sliding back starts to steer you and the load on the front tyre starts to get pretty high as it tries to cope with the braking and turning force.

Now I am guessing if you set out to break the front wheels traction under brakes, forcing the front tire to oscillate side to side would be a great way to start.

Next thing you know you are facing the wrong way the forces have balanced themselves out and settled into a new stable state... with both you and the bike lying down for a while.

All without locking the front wheel at all!!!!   Ok, you say but how likely is that to happen.  Would you believe that that single serious of events is probably the number one cause of new track riders suddenly and, at least to them, surprisingly becoming dirt track riders?

Don’t be helping out Newton!!!

First lesson with braking; try desperately to keep your weight off the handle bars and brace against the tank, do not become the link that transfers the pitching force up high onto the bars or the weave from the back directly to the front tire.   Carry the force through your legs against the tank and let the back move independently of the front.  Your elbows should be moving and bent at all times!!!!!


How’s that all work

Ok so there is a lot to get right here and we haven’t even started to talk about the transition that happens when you let go of the brake!!   So it’s pretty important to get it all right.

But before we get into all that lets look at how this stuff works and then with that understanding we can sort out a strategy to get the front brakes working the right way for us.

So, how does all this work?  Well on most modern bikes you have a lever that you pull and some discs up front that are squeezed between some brake pads as a result.  The resulting friction is like you grabbing hold of a spinning wheel and trying to stop it.  I’m sure you can imagine what that would be like, your hands would get very hot and probably you would get friction burns, as you resisted the wheels attempt to force your hand around with it.

The principal is the same though and it highlights one of the biggest things we miss a little in the normal process.  The friction between the brake pads and the discs tries to convert the turning force of the wheel into turning force of the forks, just the same way as you grabbing a turning wheel would try to force your hand to turn with the wheel, and as the weight of the bike and you resist that the energy is turned into heat instead.  This heat is then lost to the air.

I guess you grabbing the front brake could be thought of as a process of turning your forward speed into heat via the brake and resistance of it being turned into anything else, like you doing a stoppie onto your head!!!

All this heat has quite an effect and the first thing to learn about brakes is that they change how well they work as they get hot.  Some get poorer at producing friction and some get better.  The result is dependent on the material that the pads are made of and also the material that the discs are made of.

You need to understand this because, just like your tyres, you may find you need to warm up your brakes and discs to get the feel and power you would like, or on a less performance orientated bike you could find they get worse when they are getting hotter.  Brakes aren’t just brakes they change how they feel and react to your inputs as things progress.

Also there is the link between your lever and those pads.  On most bikes these days that is hydraulic, which means that when you pull the lever you force fluid down a pipe (your brake line) that then forces a piston out at the other end and squeezes those pads.

The fluid is brake fluid.  It’s a special fluid because it is non-compressible and stable under high temperatures like those you generate when you convert your forward pizzazz into heat!! 

The fluid is hydroscopic though, which means in simple language that it likes to absorb water.  It is non compressible for obvious reasons, I mean come on think about it, you don’t want your efforts at the lever going into compressing the fluid and not pushing pads against the discs.  It’s also high temperature stable, meaning it doesn’t boil and produce bubbles that are compressible when it gets hot, unlike water.   Oh wait a minute but it absorbs water?? Yeah, now you know why you do actually need to change your brake fluid yearly like the sticker says!!

An interesting note is that a brake fluids ability to resist boiling and stay stable is rated according to the DOT rating system DOT4 or DOT5 being the norm.  DOT is an abbreviation of the Department of Transportation (USA).

So we pull the lever it forces fluid down the pipe and the brake pads against the discs, further, because of the relative sizes of the piston at each end your efforts are increased like gearing and the force at the disc is ALOT more than what you can apply at the lever otherwise.

Now talking of non compressible, a lot of bikes use rubber hoses for their brake lines, these of course are expandable and as they get hot they get more expandable.   Which is why people put in stainless brake lines, they don’t give you a spongy feel as the first part of your lever travel expands the rubber and they don’t get worse as they get hotter.

So let’s look at what happens a little more in slow mo.  Firstly you release the throttle and weight transfers forward.  This is what we will refer to as the transition phase.  This particular one is transitioning from an acceleration “set” to a breaking “set”.  Transition phases are inherently instable and wobbly.  Just think about what is happening here, the compressed and stable rear suspension is suddenly released to do its own thing, the front suspension which was just in a relaxed mode is suddenly called to task and starts to take a bit more of the bikes weight.

Without proper planning the bike can wobble forward and then back like some sort of wave motion.

Squat Squish smear

Your first job is to get the thing through the transition with clear instruction into the next “set”.  So you want to move from the releasing of the throttle to the pulling on the break lever.  Get that weight forward and keep it moving forward.

So; lesson two about braking is to make your transition between “sets” positive and in one direction.

But remember that like everything it takes time.  So if you were to YANK on the brake suddenly the pads would try to stop the disc suddenly and given they have not a lot of weight transferred onto them you may find yourself with a wheel travelling slower than you would like and producing lovely squealing noises.

Also as you grab the breaks something happens to the pads, they go from cooling off in the air flow to building heat again.  This means that there is a minute amount of time where they tend to “grab” the disc rather than produce nice smooth friction.   This has to do with the way brake pads work at the microscopic level.  As they get hot they produce a “Sweat” or brake dust discharge that allows them to moderate their friction against the disc, you feel this as control over your braking rather than a simple grabbing.  This is like a disc being ground on a grinding wheel it produces filings, if a pad gets too hot its bonding agents start to lose strength and this “Sweat” increases to the point where you experience brake fade (just one of the causes of brake fade).

So the third lesson is that we want to be progressive in our transition so that by the time we have maximum brakes we have maximum weight transfer holding everything steady and also pushing the front tire down producing maximum grip for the brakes to resist and a decent “float” on the pads.

Now, progressive does NOT MEAN SLOW, it means progressive.  How fast is too fast, well by the time you are resisting the weight of your body being forced forward you have completed your transition.  So fast is pretty fast.

Most people lock brakes, given a good surface and good tires, by breaching rules 1 through 3.  If you have good surface, brakes and tires and you are progressive and let the front do its thing without interference from the back, the amount of stopping power your tire can produce is quite stunning to most riders.

Standing Tall

So we are braking progressively, without transferring our weight or becoming a “Newtonian bridge” between the back of the bike and the front wheel.  We are applying braking force and moderating the force at the lever to get the tire to its maximum grip but not beyond.

But how do I tell when I have reached the maximum braking force without answering that question from my new stable position laying in the kitty litter!!

So before I get into that there is a difference between sports bikes and cruisers etc, but I am going to ignore those differences here and take them up under Rear Brake stuff later on.   The general features are the same so I will comment on sports bikes first.

Ok, so firstly, “feel” is important and body position is also important, because given all the right criteria (good tires, road, brakes etc) chances are that the back wheel has already left the ground and you have become a unicycle. (Obviously not if you’re riding a cruiser)

So this is a good time to stress the first lesson in braking.  If you are “locked” onto the bike using the handlebars as your point to stop yourself going over the bars then by now you are in dire trouble.

You have NO feel of what is happening because your arms are locked solid, the rear of the bike has started steering the front and if you are not very lucky soon you will have a slight lean and turn that you didn’t want and again you will have found yourself using the kitty litter, probably in the way a kitty would have but trapped inside your new leathers!!!

If you have managed to avoid the “Newtonian Bridge” then you will have working forks, steering control and when the back leaves the ground you will simply feel it lift and still have steering control via your arms and none of that additional force going through the front. 

But better still you will have found that as the rear lifts it gets higher and higher if you keep applying more brake and the limit of your braking is, well the limit of your stoppie!!!  Easy right... use the right technique and the limit is how high you are comfortable with the back being.

But what if the road conditions are not so good to give you that much grip, wet for instance?  Well then you have to ride like the guys on the cruisers using other indicators of when maximum grip is achieved.

Feel the squeal

Those guys on the cruisers know that when they approach maximum braking a few things happen and if they have not braced themselves against the bars they can feel them. 

Firstly the front will usually start a very slight “chatter” like the grip on the road is oscillating.  Then the front will either squeal or move straight to the next indicator, the “chatter” will stop and the front will get smooth.

This last one means the tire HAS LOCKED.  This is the first indication and if you ease off the brakes and back on you’ll be fine.

If you don’t you move right into the locked front wheel fully expressed.

 The brakes aren’t working

The weight will transition back again and the pressure will come off your body, the front with sit up and move away from you as the bike feels like its accelerating. 

Wait a minute! That’s what happens if I let go of the brakes!!!  So my natural reaction here is to grab the bloody things harder because they obviously are not working!!!.

This last phase is the gotcha... you need to be dialled in because the symptoms ARE like you have let go of the brakes and your natural reaction WILL be to grab them harder, unless you are trained and planning to feel it and again release the pressure and re-apply.

A locked front wheel DOES NOT MEAN YOU WILL FALL OFF.  Failing to react to a locked front wheel will.

Fingers and other things

So if my maximum braking is with the back wheel held in the air or the front chattering and the next higher braking point  is having the bike ride me off into the kitty litter or locking the front and visiting the same scratching box, then I had better have some good fine control, especially at full braking force!!  How do I do that?  Damn good question and one that is really controversial.

Depending on where you learnt to ride or the habits you have formed you are either a one, two or four finger brake person.  Some of you will have very strong arguments for how you brake, how many fingers you use etc.

Well so do I;  So in the interests of not simply stuffing my opinions down your throat I’ll attempt to  explain why I hold my opinion, which is by the way that you should, so long as your bike is capable, be using two fingers for your braking and specifically your first two fingers.   That would be the same ones you would use to demonstrate you disapproval to me if you are a vigorous four finger exponent.

So firstly let’s look at how your fingers work.  We are a very complex animals with years of evolution, if you believe in that stuff or perhaps I should say wonderful design, having been grafted into our bodies.

Our hands in particular are extremely well developed for what we use them for, there are a total of 27 bones in the wrist and hand and the muscles that control it all are large in number.  We have muscles in our forearms that are called extrinsic muscles of the hand and we have much smaller finer muscles in the hands themselves called intrinsic muscles.

Contrary to popular opinion, we are not the only primates possessing opposable thumbs.   But we are pretty famous in our own minds for having them.

Interestingly we are unique in the animal kingdom in the ability of the small and ring fingers to rotate across the palm to meet the thumb, owing to a unique flexibility of the carpometacarpal joints of these fingers, down in the middle of the palm. This is referred to as "ulnar opposition" and adds unparalleled grip, grasp, and torque capability to the human hand.

So first thing to get is that in the human hand the two smallest fingers together with our thumb have evolved to give us a really strong grip on things.

This even goes all the way down to the length of the finger bones in each finger; they actually curve as you bend your hand, in a spiral NOT a circle.  These spirals and the length of the finger bones actually relate mathematically to Fibonacci spirals.   The bones are also flat on the back and curved in the palm again to maximise this ability to grasp and hold.

The spiral formed by the smaller fingers is smaller and in keeping with their intended purpose which is to grip and hold against the thumb, whilst the first two fingers have longer bones and a wider spiral to afford more control.

Further to this the balance of power between the intrinsic or fine muscles IN the hand to the extrinsic or strength muscles in the forearm and also differences due to leverage et al for these two sets of fingers mean you have more fine control over your first two fingers.

Net net you can write and draw easily with your first and even second fingers because you have fine muscle control and dexterity using them, but find it very difficult to do with your smallest fingers because they are designed to grab and hold strongly not for fine work.

Combine that with the fingers sitting at more and more leverage along the lever, your need to hold onto the bars whilst braking and a modern bikes ability to lock the front wheel with even one finger and you start to see that perhaps you want to consider using only your first two fingers for your braking and leave the little ones to hold on for you.

If you are still not convinced trawl through everything you can find and see if you can find a rider doing a stoppie using all four fingers, or worse still using just the small fingers.  I think you will find that they have all learnt that to get that fine control, you need to work with your bodies design not against it.

I started all this by saying IF YOUR BIKE IS CAPABLE because I started riding when brakes required all four fingers and a burly forearm’s worth of strength to get the thing to stop.  So you need to make sure two is enough for your bike.  This may apply to some cruisers but very few sports bikes these days, if any.  Second is you need to ensure the brake lever is adjusted correctly so that maximum braking is achieved BEFORE you pull the lever all the way back to your fingers and prevent yourself from getting the best from your  brakes.

So, last lesson about braking is to learn fine control at maximum braking using practice and your body’s natural design.


To Rear or Not to Rear 

So in the next section I’ll talk about using the rear brake.  But just quickly I am often asked should I worry about using the back brake at all.  Now note this is always by sports bike riders who have discovered that the back is barely touching the ground under strong braking.  Cruiser riders never seem to ask!!!

The truth is the rear has a purpose, it is a tool.  You don’t use your front brake as an emergency parachute (well not most of the time) you use it to control your bike and speed so that you are ready for the next transition phase, from braking to cornering “sets”.

The rear is the same, only where and how you use it as a tool to control your bike is slightly different.  So should you use the rear, absolutely yes.

 

Just remember that it might not be worth using by the time you have daylight seeping under the back tire.