There's a well known adage in aviation, particularly for fighter pilots, and it goes like this:
When an emergency arises your performance drops to the lowest level of training.
I have never come across a more realistic observation of deterioration of skills when under hostile fire. Practicing for emergencies is as good as the emergency simulation you do, actually a little worse than that. Which is why you need to practice so much that the needed actions become second nature, a 'reflex'. And practicing the 'right' technique is critical because the 'reflex', once embedded in muscle memory, will not allow you to think and correct it if its wrong.
What Tenhut, csgup1, rossiter and quite a few others have put forth here is about not
just the need to learn the skills but the criticality of learning the RIGHT technique. Becoming a proficient motorcyclist is a lifelong endeavor. You are either busy learning new skills or practicing old ones.
Braking is a very 'critical' skill for a motorcyclist. The real art in going fast is to know when to go slow and how to go slow. And getting it right, practicing it right and executing it right is what will keep you alive. Its one major 'vital' in the
Vital few and trivial many aspects of motorcycling. Learning braking in real life urban riding situations is about including road traction assessment into your braking action. Practice the gentle squeeze to firm squeeze technique any and every time you brake while riding. Feel the firming up of the front brake lever under you fingers. Scan the road ahead for adjustments to braking. Check those RVM's before, during and after braking. Feel the weight transfer drop the front and know that the rear has gone light by an equivalent amount. Practice each and every time you brake, so much so that you unthinkingly brake like that everytime. Aim for a point to stop and see how well you assessed the distance and braking effort needed. See that little piece of paper on the road, try to steer around it while you brake. Set up your line and entry speed to those turns to perfection. In a well set-up turn, whether on road or on track, you'll not need emergency mid-turn corrections. It is only when you set up a turn on assumptions rather than knowledge of the road/track ahead that you need mid-course corrections.
Incessant learning is essentially what it is all about. Remember that a skilled rider will use his skilled brain to avoid needing those superior skills. Paradoxical but actually the only real way of enjoying your motorcycling and yet staying alive doing it.
Lots of useful information has been shared about
'trail braking' here. I'll add a visual aspect to it and start with a diagram that I've taken from a book 'Sport Riding Techniques' by Nick Ienatsch.
The orthodox riding technique states that we finish all our braking and gear shifting while the bike is upright, enter the turn on constant throttle and just past the apex, feed in the throttle progressively. But the preferred method now is using 'trail braking'. Trail Braking is a technique where the rider progressively reduces his braking force as he gets deeper into the turn and closer to the apex. This progressive and smooth reduction in braking is to use a progressively larger share of traction for turning, a need that hits its maximum at the apex, where the braking input is reduced to zero. Trail braking has two major benefits: 1. It allows for braking while turning, allowing the rider more control over his situation. and 2. The rider can carry speed deeper into the turn and by slowing progressively towards the apex, has more reserve traction to trade for the same needed for turning.
Post-apex, progressively opening the throttle makes for gradual rearward weight transfer allowing the rear tyre time to gain traction and transfer power for acceleration.
In practice, the overlap between trail braking and powering out is a smooth blend, always balancing the available traction to the traction needs.
Trail braking is a difficult skill to master primarily because as you brake during the turn, you put additional loads on the contact patches which are already fighting a hard battle for traction by countering the outward tangential force. Adding braking loads to the equation takes you closer to the edge of the traction envelope and even a slight excess in loading can lead to a washout.
As for the unassailable logic of favouring the front brakes, the related and at times disconcerting nose-dive and what happens when we do so was something I had posted earlier in another thread
here quite sometime back. Reproducing the same below to maintain continuity as has been the case with the trail braking part above which is also taken from the same thread:
I guess we need to get back to high-school physics to clear this thing about forward weight transfer under braking, its benefits and demerits in its entirety.
Weight transfer is a physical reality that has to happen, whether there is a suspension system pre se or not. Refer to the fig in my previous mail that I am reproducing below:
Braking produces a force (because the rider/bike combo is in motion and braking means deceleration) that has eventually to act through the front tyre contact patch where it is countered by the force of friction between the road and the contact patch. Since the connection between the contact patch and the rest of the bike is primarily through the fork, a large component of this force travels down the forks. The exact quantum of this force transfer can be calculated by referring to the fig below:
As the forks are raked at an angle to the vertical, the force transferred through them can be calculated as a product of the total force and the Cosine of the angle of application of the force. Here the angle is the 'rake' angle minus 90deg (since the rake angle is measured against the vertical). Assuming a rake angle of 25deg and a braking force of 1N, the force component acting down the forks would be = 1 (N) x Cos(65) = 0.4226. Meaning that some 42% of the braking force shall act through the forks.
Let us assume a ZMA (about 150kg) with a rider weighing 70kg coming to a panic stop. Stock tyres on clean tarmac can give a decelration equal to about 1G i.e. about 9m/sec2
So the total force generated would be like F= M x A = 220 x 9 = 1980N
1980N x 0.42 = 836N = 85kg (appox)
So the forks get pressed downwards by a force equivalent to 85kgs. No wonder they get compressed.
As you can see, the 'softness' or 'stiffness' of the suspension set-up has no meaning for weight transfer. The 'weight Transfer' is a Force that is generated due to braking. It is just that with a softer suspension, you get a larger deflection of the springs, more dive and so it 'feels' like there has been a LOT of weight transfer occurring.
And about Trail Braking: Loading up the front during a turn is not a ‘needed’ thing. It just happens because of braking and also because of the centrifugal force generated during a turn that compresses the suspension. Ideally, a completely unloaded front is the best as all the available traction is there for resisting the slide (the tangential force that wants to slide the bike ‘out’ of the turn). But in the real world, we can only strike a workable balance between the various forces to our benefit.
And suspension dive is what the rider needs the ‘least’ during a turn. The ‘quick steering’ benefit is way offset by the detrimental effects of a bottomed out suspension and an excess demand on the traction reserves.
In a nutshell:
- Learn to depend upon and use the front brake to fulfill most of your braking needs.
- The rear brake is useful mostly under low traction situations or at low speeds where front end dive leads to instability. (Eg: lane splitting as a stop light)
- Braking is not just about 'braking' but also about reading the road that you'll be braking upon.
- Practice, practice and practice but practice right. Learn it wrong and it takes longer to get rid of wrong learning that it takes to learn right. And to know whats right, you have lots of people on this forum and the internet as a vast repertory of information.