Posted 27 May 2008 - 06:12 AM
I thought that before I do a post about going really fast, maybe a post about stopping would be an Idea : Hopefully you have set up your suspension properly and are already noticing an improvement in braking.
A motorcycle's brakes are both its most powerful component and the most difficult to master, I can say with confidence that even those riders serious confident enough to go quick have difficulty getting much more than 50 percent of the braking potential from modern Bikes.
As impressive as today's 1000cc Bikes are, accelerating to nearly 150 mph in a quarter-mile (1320 feet), their brakes can haul them back to a stop in about half that distance. Most riders can get better than 90 percent of the engine's potential by simply launching well and twisting a throttle, but achieving maximum braking is a different matter altogether.
While most riders assume effective braking involves more bravery than brains (some like to cite Kevin Schwantz's famous quote: "Wait 'til you see God (or a Hedge) then brake!"), it's better to think about what specifically you hope to accomplish with braking and how to best achieve that goal. The first basic premise is that the whole purpose of braking is to arrive at a particular spot at the desired speed; whether it's stopping at Traffic Lights or arriving at a 45-mph corner entrance at 45 mph. In high-speed riding, too much emphasis is put on where we begin to apply the brakes, with the misconception that the later we begin braking the better. Consequently, not enough thought is put into arriving at the corner entrance fully prepared, at your desired speed and in the correct gear. It's all too common to see a panicked rider fully engaged in heavy braking while hastily stomping the last downshifts as he blows past the turn-in point. Get your heavy braking and downshifts done early. Bikes, on the whole, are a bit like Blokes, only ask em to do one thing at a time and they are fine. Anything more and they get confused
It's also important to understand weight transfer, and why our bikes are able to literally stand on their nose under heavy braking without losing front-tire traction. Under acceleration, weight is transferred to the rear tire, and the rear suspension helps gain more rear-tire traction by compressing slightly and allowing more of this weight transfer to occur. Under braking, the weight obviously transfers to the front end, and here the front suspension aids front-tire traction by compressing and concentrating more weight onto the tire contact patch. To get the traction we need for maximum braking requires smoothly rolling off the throttle and then smoothly applying the front brake. If you suddenly chop the throttle and grab the front brake lever in a panicked death grip, so much weight is immediately transferred to the front that the fork actually bottoms out, which not only compromises chassis control, but also front-tire traction. When the front fork bottoms out under braking, so much weight transfer occurs that the rear tire lifts off the ground, which can quickly lead to stability problems, and without any fork travel to absorb bumps while braking, it's very easy for the contact patch to lose grip. Being smooth is crucial to the bike's stability, the rider's confidence and the feeling of control; it's nearly impossible to brake effectively without confidence and control.
You should always practice maximum braking in controlled conditions where you can safely explore your limits. In this situation, many riders (myself included) ignore the rear brake entirely (manly cos on the Tuono it’s merely ornamental) . Others choose to use the rear brake to balance the chassis. There are valid reasons for both techniques, so try them both to see which works best for you. Remember, however, that a Motorbike is able to transfer all its weight to the front during braking, so extreme care must be taken when using the rear brake, to avoid wheel lockup.
While practicing braking technique, begin with early braking points to perfect the sequence without the stress of a fast-approaching corner. Initially, smooth is slow, but as you master the technique, you'll find you will be able to remain smooth while executing these inputs in an ever-shorter period of time. Keep in mind, however, that doing it quickly is optional-doing it smoothly is not.
Once the weight is transferred forward and the fork is compressed, it's time to transition to maximum braking, really squeezing the front brake lever (again, smoothly). Build up the level of lever pressure incrementally over many, many sessions, and you should feel the limits of front-tire traction and the rear tire lifting. Oh on this point I would to add that the ole XJR is capable of lifting the rear under full braking, so don’t underestimate the power of ya Tractor. Don't rush to find the limit; this is delicate business and the price of exceeding the limit is a tad painful. To best judge your corner-entrance speed, try to get your heaviest braking done early, allowing you to release the brakes smoothly over the end of the braking zone, transitioning from near-maximum fork compression to perhaps 50-70 percent of its stroke, where fork travel usually ends up under maximum cornering force.
If you want Motorbike racing you should understand now what they mean when a rider says ‘he let the brakes off’ whilst stuffing another rider into the corner.
Remember also you need to release the front brake even slower than you squeeze it on. This allows the weight to transfer more evenly front-to-rear, to prevent the front suspension from rebounding (springing back) too quickly and upsetting the chassis as you're entering the corner. At the same time, you need to be careful not to overload the front contact patch with too much braking as you lean into the corner, causing the front tire to slide or push, which to the vast majority of mortals is quickly followed by dragging your elbow and then helmet in rapid succession.
In my experience, more crashes are caused by trailing the brakes too hard and deeply into the corner than any other method of losing traction, so beware. Front-tire traction is never more critical than while turning into a corner with the throttle off and the front brake on, so this balancing act of braking force versus cornering force is best done with delicate care. That said, you can brake deeper into the corner than you think, it's just prudent to not push the limits of trail-braking too much.
Now that we've gone over how to brake effectively, it's important to remember that even at their best, braking distances increase exponentially (the physics is that kinetic energy equals one-half mass times velocity squared), not linearly. In other words, while an expert rider can bring a good bike from 30 mph to a stop in about 30 feet, at double that speed, 60 mph, it takes 120 feet. At 120 mph, figure close to 480 feet of stopping distance and so on. This is the fact that catches many riders out. I seldom tell anyone how fast is safe to ride, but I absolutely believe that whatever speed you choose to ride, be damn sure you first have plenty of experience stopping and steering from that speed.
Remember any arse with a ‘Blade can go fast, but can you stop the thing if you need to.
There's no triumph over a corpse.
But a beaten opponent, who will remain beaten every day, for the remainder of their sad and wretched life.
Is something to treasure.....
Posted 19 February 2014 - 07:06 AM
Rear Brakes are to stop wheelspin coming out of the corner . . . Fourex
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