Provided you can maintain board/snow contact, and are able to shape a turn, there isn’t much difference between riding smooth snow and bumps. There is some sort of misguided consensus out there that the only way to ski or snowboard moguls is to point yourself down the fall line and thrash yourself silly, slamming yourself off of each bump in order to brake your speed. (when we ride in the woods, do we hug each tree to slow down?) The assumption follows that only by continually attempting and failing in this approach will this approach ever be learned. What say we learn to crawl before we run?
There are two important aspects involved in successful bumping: consistency of speed, and maintenance of balance. These two items are somewhat interdependent; if you are out of balance, you will have difficulty working to sequentially cut your speed, and if you move too fast, the uneven surface will challenge your balance.
Speed control on a snowboard comes about as a function of our turn shape. By changing our direction of travel into and out of the fall line, we can obtain a comfortable velocity. In order to shape a turn, we must maintain maximum board/snow contact; as soon as we lose contact with the snow, the board flattens out, our turn shape deteriorates, and we tend to move back into the fall line, increasing our speed. To best maintain contact with the snow, we should be relaxed in posture, so that variations in terrain do not bounce us up and off the snow. As the magnitude of terrain variations increase, the amount of flexion/extension of our legs should increase somewhat proportionally. Since the surface in general is not smooth, we should not expect that our tracks will be surgically precise and unbroken, nor should we expect that we will have a consistent platform to work off of.
To remain in balance while riding a snowboard, it would be beneficial to make as few disruptive movements as possible while turning. If we gyrate around with our upper body/arms, we open ourselves to the possibility of compromised balance. If we can maintain a quiet upper body, that part of our body will move consistently in whatever direction our turn takes us, and as such may provide us with stability should the need arise32. If you can successfully separate the upper body from the turning movements of the lower body, you can turn your board without interference, and thereby control your speed. Even though it may not make sense immediately, or in the confusion of the moment, try to start a turn with your feet and not your upper body.
Practical exercise line
Find a section of bumps that are not too intimidating, on a trail with a little width. Begin your descent by traversing the hill, turning in whatever way is necessary at the end of the traverse. We are not trying to work on the shape of the turn yet, just the ability to flex and extend our legs to maintain board/ snow contact. As you traverse the bumps, imagine that your head is always the same distance from the tops of the bumps. In order for this to happen, you have to be very active with the movement of your feet. Try to keep your upper body quiet, so that your arms are not swinging about randomly in a search for balance.
As you become comfortable with a smooth, balanced traverse, begin working on the shape of your turn as you connect traverses. If the trail has sufficient width, you can begin several turns over the course of the traverse, without actually dropping into the fall line. Gradually, you can alter the radius of the turn at the end of each traverse.
If your balance is good, and you feel comfortable with the change in speed, a wide radius turn at the end of each traverse will bring you into the fall line and give you the time to shape a turn by maintaining contact with the snow. Don’t try to drag your hand on the snow. Exercise a light touch to avoid excessive bouncing and a loss of balance.
As you move further down the hill, shorten both the traverse and the radius of the turn that connects them. Try as hard as possible not to swing your arms to start a turn, as it will only affect your balance later in the turn. When you reach the point where you are turning mostly in the fall line, make an effort to keep your shoulders square to the fall line33. If you can do this, you will be able to maintain your direction, rather than drift off to either side as your upper body twists. I have found that if I let my heelside arm drag behind me in the air, my shoulders tend to stay where I want them. The trailing arm functions as a rotational counterbalance and stabilizer.
Be patient with yourself and your board in the bumps. Riding bumps well is not something that just happens overnight. Like anything else worth doing, it takes time, and is dependent upon a good technical foundation. Investigate use of bamboo as stabilizing element?
(32) If we… And then I realized the causal link between flailing arms and binding setup. If the movements of the feet are blocked, movements of the arms are necessary to facilitate upright stability. A quiet upper body is the product of good riding, not the other way around. When riding in the bumps, all other things being ok, the mass of the arms can be used to maintain/affect rotational stability of the upper body. Unwanted rotation can be slowed by moving the mass of the arms selectively outwards, and recovery to neutral can be facilitated by moving the mass back towards the core.
(33) When you… See previous note.