The Unstable Toe Side Turn

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In the previous post Anatomy of Snowboard Carving Turn 1 I claimed that the goal the rider needs to achieve during the turn is to assume the most optimal position on the snowboard. Position that allows the most control over the body and that has the most spare resources for maintaining the balance.

So why assuming this position during toe-side turn is the most important thing to do ?

Before I answer this question, let me tell you a little bit about open and closed control systems. Closed systems contain a feedback loop – feedback is used to regulate what is going on inside a system. They also tend to be stable – the feedback helps to stabilize the system. For example imagine pressing on a gas pedal in a car – the car will accelerate for a while and eventually will reach it’s stable cruising speed (even if it’s a dragster it will eventually reach it’s max speed for a give throttle level and will not accelerate any further). Simplifying a lot, you can think of air resistance as feedback. The faster you go – the bigger the resistance, so the car accelerates slower, until it reaches the target speed. The car’s acceleration can be considered stable.

Open systems do not contain feedback loop. The are mostly unstable. Imagine there was no air resistance – if you pressed the gas pedal then, the car would accelerate for ever. Going faster and faster. So the car’s acceleration would be unstable. We could easily stabilize it – the driver after reaching the desired speed could switch off acceleration and drive with desired speed.

In the first case the car effectively regulates the speed, in the second case we need the driver to regulate the speed.

Toe-side turn is essentially like open control system. But why ?

Picture taken from this video: youtu.be/Xr6wLJ9gYEo

It has to do with the way our knees work – unfortunately (?) they only flex one way.

To follow a good trajectory in a turn, rider should maintain fairly constant inclination angle during the turn. Like on the picture above – rider looks very stable. What would happen if he was to ride over bump or a hole ?

  • hole – that means that the board suddenly ‘rides away’ from the rider. The natural way to counteract would be to straighten the legs… except that makes the board flatter (less on the edge) and that will cause the board to run away from the rider even more – so the situation is unstable
  • bump – the board suddenly gets closer to the rider. So the rider reacts by flexing the knees more (absorbing the bump) – which puts the board more on the edge and pushes the board even closer to the rider! Unstable again.
There is not much we can do about it – the system is essentially unstable… but the rider can try to stabilize it:
  • The most important thing is to have a huge potential spare balance left during the turn. We achieve this by riding on top of the board without many parts (knees, butt, upper body) sticking out on either side. That allows for a shift in upper body compensate for the unbalance. Look at the picture above and see how well the body of the rider is distributed on either side of the red line.
  • the knees should work towards the front of the board as much as possible. That minimizes the effect of changing the board angle during flexion/extension of the knees (as opposed to knees sticking out to the side, rear knee in particular)
All that is achieved when rider goes through the carve in counter-rotated position and the inside arm is ‘pulling’ the rider forward.
This picture bellow illustrates how far you can go with this position:

Alexander Bergmann (GER) © FIS/Oliver Kraus

Alexander Bergmann (GER) © FIS/Oliver Kraus

You can see how the body is perfectly over the board, how far the rider is leaning into the turn and how the knees work in the forward direction as opposed to working to the side. I recommend looking at some pictures from FIS WC and noticing the body position of the riders during toe-side turns. You can find more at http://www.fissnowboard.com/

And here is my version of a toe-side carve, riding just for fun:

Bart Czarnecki frontside

More about Zen and Snowboard Carving Turn, Yin-Yang and the Backside Chill soon…

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