BODY POSITION & THE ART OF BIKE HANDLING

June 27, 2014
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In the early days of motocross, riders kept their body weight as far back as humanly possible. Viewing old race footage reveals some of the greatest stars of the sport sitting on their rear fenders. Why did they stay so far back? The ergonomics of the bikes they raced demanded it. With limited suspension travel, riders from the 1970s sought the safety of the driven rear wheel.

In the ’80s, riding styles began to change. As suspension travel began to increase in the late-’70s, motocross racers began to move forward. By the mid-’80s, the popularity of the “attack position” slowly but surely moved the motocrosser over the front of the bike.

BE A CENTRIST AS OPPOSED TO A LEFTIST

Although body position is relative to the angle of the bike in relationship to the horizon, the modern rider’s “centered” position is no longer in the center, but closer to the front wheel. Why?

Front suspension:
Modern front fork design, stiffer spring rates and effective anti-bottoming devices allow a modern rider a greater margin of safety than the old-fashioned, oil-damped, six-inch travel forks of the ’70s.

Frame geometry: Steeper geometry has forced the rider to weight the front of the bike in order to increase bite. Bikes of 25 years ago had slack 31-degree head angles, rearward weight biases and low centers of gravity. New bikes are taller, weighted more to the fore and tippy. Staying forward helps counterbalance the new steeper 27-degree geometry.

Tracks: Modern track designs have drifted away from fast sweeping corners to tighter Supercross-style turns, often with deep ruts or berms (made deeper than in the past by long-travel suspension). Since staying forward enhances cornering, modern riders have been drawn to the front by the complexity of modern track designs.

BE FLEXIBLE AND BE FAST

Body position is determined by terrain, vehicle output and rider input. When going uphill, a rider will always move forward because of the rearward weight shift. Downhill riding demands that the rider move rearward to compensate for fork compression, weight shift and gravity. Apart from terrain changes, the attitude of the bike also affects rider positioning. The differences between hard braking and hard acceleration highlight the obvious direction in which the rider must move to compensate for natural forces on the chassis.

As a rule of thumb, pull yourself forward in the corners and allow G-forces to help you find the center under acceleration. The Gs will hold you in place, as long as you aren’t in the wrong place on the saddle. When you are out practicing, take note of where you sit; then try to sit an inch or two farther forward. It is easier to move back in an emergency than it is to move forward.

Your motorcycle, along with everything tangible on this planet, has a center of gravity. In engineering terms, it’s simply called the “CG,” but most of us call it the “balance point.” Motocross chassis designers go to great lengths to place the engine, wheels and suspension components in exactly the right location to get a motocross bike’s CG perfect.

The higher the CG is located on a motorcycle, the more likely it is to have handling issues that only the rider can fix. Paradoxically, you will be horrified to discover that the CG of a modern motocross bike is purposefully high — way high. For a machine that is required to skim across the earth, fly through the air and swivel about its CG, a high center of gravity is a plus. One of the tools of any motorcycle racer is weight transfer. It makes a 228-pound machine feel light or heavy depending on what the situation calls for. When a motorcycle accelerates forward, the bike rotates around its CG, causing the front tire to get light and weighting the rear tire. Because of this weight transfer, there is a heap of traction on the back tire when a racer needs it most — roosting out of a corner. The downside of this is that when a bike decelerates, its mass rotates towards the front wheel and it is possible for the rear wheel to lift. This dance of fore and aft weight transfer is the root of going fast. But, the rider has to be able to move in sync with a constantly changing world. When a bike accelerates, it is a different machine from one that is braking. When it flies through the air, it requires a different body position than when it is buried deep in a berm.

COIL LIKE A SNAKE

The key to moving forward and backward is to be flexible. And the key to being flexible is to be standing up whenever the bike is dancing through bumps, skating into corners or flying through the air. From a purist standpoint, the only time a rider should be sitting is when he is in the middle of a corner. To make standing up work best, keep a slight bend in your knees and an arch to your back. Grip the tank with your knees — this isolates your upper body from a lot of the mass below it. If you do everything else wrong, but are standing up and your knees are clamped onto the gas tank, you will probably survive. The standing, coiled and arched position offers more variations in body English. Don’t sit or stand on your bike like a lump of glutinous Jello — be alive; be vibrant; be ready for action.

Body position can make the difference between winning and losing (and in extreme cases staying on the bike as opposed to flying off it). Make every effort to tune your body to the rhythm of the track. Stand, sit, bank, lean and arch with the terrain. Help your bike, don’t fight it.

 

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