The Physics of Flow: How Longboard Skaters Generate Thrust
Longboard skaters harness the laws of physics to generate flow. While riders might not always know the exact principles at play, they can feel those equations pushing and pulling them forward as they carve through S-curves.
From an engineering perspective, this is a dynamics problem best explained with force vector diagrams. A deep understanding of rider technique combined with longboard truck setup leads to a simple explanation.
Bottom Line Up Front
Through successive S-turns, the front of the board can "pull" and the rear can "push" the rider forward simultaneously on any kind of longboard. Minimizing drag while optimizing thrust depends heavily on the longboard's steering geometry and the rider's technique, all of which are explained below.
Key Terminology
Longboards are specialized skateboards that the rider can turn by leaning, without the need to lift the front wheels off the ground, like with regular skateboards. They are considered counter phase turning mechanisms. They don't need to be peculiarly "long" to be longboards, but they can be. For example, the Hamboards® Classic longboard towers at 74 inches while the Hamboards Twisted Fin longboard is 26 inches. What they share in longboard DNA is the Hamboards HST® Truck System.
We categorize longboards into three "center of turning" types:
- Centered
- Back Foot
- Rear Axle
We also refer to three primary riding styles:
- Carving
- Surfskating
- Pumping
By analyzing force vector diagrams, we can explain how riders create forward force without foot pushing. Forward force vectors are known as thrust, while backward force vectors are called drag. Understanding why the center of turning is critical for different riding styles is essential.
With proper technique, skilled riders can generate forward thrust (pump) on any type of longboard, though certain setups work better for different riding styles.
The Hamboards HST Truck System features interchangeable components, allowing any deck to be configured for different riding styles. Four different kingpin pivot angles (0°, 20°, 40°, and 55°) can be combined to match any riding style.
Longboard Types by Center of Turning
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Centered Longboards have equal turning in the front and rear, with the center of turning located at the center of the wheelbase.
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Back Foot Longboards have more turn in the front than the rear, with the center of turning located near the rear foot.
- Rear Axle Longboards have all the turning in the front, while the center of turning is located at the rear axle.
Riding Styles Explained
Carving
Carving, a term borrowed from surfing, is the original means of propulsion in longboarding. The rider uses a Centered Longboard, stands over the middle of the board, and makes sequential S-turns while the front and rear axles travel a virtually identical path. Carving resembles snowboarding on edges and surfing on rails.
World Champion Surfer Cory Lopez demonstrates longboard carving on a Hamboards Twisted Fin with HST 40/40 trucks, creating forward thrust powerful enough to climb uphill. Notice how his front hand stays over his front hip, allowing him to twist his body core and create lateral force with both feet through powerful S-curves. Cory generates roughly equal forward thrust vectors with both front and rear wheels—an aerobic method requiring high skill and fitness.
Cory powers his rear foot opposite to his front foot, causing him to feel front pull and rear push equally and simultaneously. He uses this same technique on his shortboard surfboard to generate thrust and gain speed on a wave.
Here's a magical full video with Cory Lopez and his kids.
Surfskating
Surfskating blends carving and pumping. The rider uses a Back Foot Longboard, stands over the middle of the board, and makes sequential S-turns. The front axle travels a wider path than the rear axle, allowing the rider to create deep carves and generate a forward force vector similar to surfing.
Hunter Joslin, the iconic surfer and founder of IndoBoard, demonstrates surfskating on a Hamboards Burst with HST 40/20 trucks, accelerating along a flat surface. His front hand stays over his front knee, enabling him to twist his body core and create lateral force with both feet through powerful S-curves—a technique requiring substantial power, skill, and fitness.
Hunter primarily steers with his front foot while powerfully driving his rear foot in the opposite direction at precisely the right moment. Though he generates a much larger front force vector (pull) by moving his front foot, Hunter pushes hard with his back foot too, resulting in a combination of front pull and rear push.
Here's an amazing full conversation with Hunter Joslin teaching us all about balance and flow.
Pumping (Long Distance Pumping or LDP)
Pumping is a specialized longboarding technique where the rider uses a Rear Axle Longboard, stands mostly over the front of the deck, and makes rapid sequential S-turns. The front axle travels a wide path while the rear axle follows a very narrow path, maximizing the forward force vector.
World-class Long Distance Pumping athlete Landy Cook demonstrates longboard pumping on a prototype 60-inch carbon fiber reinforced, foam core board with HST 55/ZR0 trucks, efficiently accelerating on a flat surface. Both his feet are positioned near the front truck, allowing him to swing his lower body like a pendulum and drive the front wheels in the turning-direction through powerful S-curves. Landy creates only front thrust (pull) with zero rear thrust (push)—a powerful, highly efficient technique that can be mastered with good rhythm.
Landy feels only front pull, making this very efficient. Pumping has become an essential skill for endurance distance skating.
Landy is only feeling front pull and it's very efficient. Pumping has become a quintessential skill for endurance distance skating.
The Mechanics of Forward Thrust
The illustrations show the precise moment when the rider pushes the front in the direction of the front wheels' path and pushes the rear in the direction of the rear wheels' path to create forward thrust. It's a kind of twisting or "scissoring" motion. Forward thrust comes in pulses, propelling the board forward at just the right point during sequential S-curves with synchronization and rhythm.
When riding through S-curves, there is one force vector for both the front and rear legs (feet). When the rider pushes in opposite directions with the front and rear feet, they create forward thrust: pull from the front and push from the rear.
Technique Adjustments by Riding Style
For Surfskating: Riders should push much harder on their rear foot because they have less "rear turn" to work with, as the center of turning is already under the rear foot. This is why surfskating coaches encourage riders to push harder with their rear foot, though most new riders tend to just wiggle the front truck.
For Carving: Riders should push equally on front and rear feet in opposite directions. If they push with both feet in the same direction, the rear thrust vector is "canceled out" by a front drag vector. But when the rider pushes in the opposite direction with their front foot, they get two forward thrust vectors.
The illustration above shows how any longboard with adequate steering can be ridden to create forward thrust.
For carving (diagram above), the rider is advised to push equally on front and rear feet, in opposite directions. If they push with both feet in the same direction the rear thrust vector is "canceled out" by a front drag vector. But when the rider pushes in the opposite direction with their front foot, they get two forward thrust vectors.
The Hamboards HST Truck System
When Peter Hamborg and his kids invited me to help with Hamboards, they wanted a big skateboard that feels just like surfing. It took time to understand what they wanted, but we eventually developed the HST truck system that delivers the feel they were looking for.
Unlike most "surf skate trucks" that swivel in the front, the HST truck system leans and turns but does not swivel. This means riders can't "cheat" the HST Trucks—they must synchronize their entire body with the board. Riders need balance, rhythm, and coordination of their center of gravity with the board to achieve flow, whether carving, surfskating, or pumping.
As Hunter Joslin notes, "There's no better surf training in the world than a good skateboard." Mastering the Hamboards Burst with HST 40/20 or 55/20 trucks, combined with balance training on Indoboard, will advance skills and create muscle memory that benefits riders when they surf, snowboard, or slalom ski.
The HST system can be applied to any longboard for different riding styles. Since these are all counter-phase steering systems, the turning radius is defined by the Pythagorean theorem. Riders seeking a shorter turning radius need to choose a setup that works best for them.
Referring to the image above, the HST system can be applied to any longboard for many different riding styles. Since these are all counter phase steering, the turning radius is defined by Pythagorean theorem. If the rider wants a shorter turning radius, they'll need to choose a set-up that works best for themselves. The greyed rows are recommended.
Conclusions
With proper technique, skilled riders can create forward thrust (pump) with any type of longboard skateboard that has a high degree of turning capability. It comes down to twisting or swinging the lower body at just the right moment. The longboard's center of turning location is critical, and the riding style needs to match the setup.
Centered Longboards can be pumped to maximize forward thrust, pulling from the front and pushing from the rear, though this requires significant energy and skill. Most traditional Hamboards are Centered Longboards.
Back Foot Longboards offer a comfortable combination of carving and pumping with proper technique. Most surfskates are variations of Back Foot Longboards and are generally easier to learn to pump. All Hamboards decks can be converted to Back Foot Longboards.
Rear Axle Longboards are the most efficient for optimizing forward thrust through pumping. Optimizing the front turning angle and using a longer deck yield the best forward thrust vectors, though the turning diameter can be quite large. All Hamboards decks can be converted to Rear Axle Longboards.
Hamboards HST Trucks are interchangeable and modular. They can be set up for Centered, Back Foot, and Rear Axle longboards with minimal effort, allowing riders to adapt their boards to their preferred riding style, whether Carving, Surfskating, or Pumping.
Author: Don Sandusky, PhD - Hamboards and SUPSkate
Contributors:
Steve Ng - Hamboards and SUPSkate
Abraham Paskowitz - Hamboards and "first family of surfing"
Mark French, PhD - Purdue University
Scott Imbrie - Founder Original Longboards
Leonard Leffler - Champion Ultraskate Athlete and Skate Poling Pioneer
Andy Andras - World Record LDP Athlete and owner of Miami Ultraskate
Cory Lopez - World Champion Professional Surfer
Hunter Joslin - Iconic Champion Surfer and Owner of Indoboard
Landy Cook - World Class Skate Poling Athlete
Bob Foster - Philadelphia Skating Legend, PA
Earl Stout - Philadelphia Longboard Legend, PA
Bill Fitzhugh - Satorial Distribution, UK
Josh King - Team Rider - Mid Atlantic USA
Mark Harris - Team Rider - Florida
Tarzan - Team Rider - Huntington Beach CA
Chris Slaughter - Longboard Aficionado - Florida
Connor Baxter - Fastest stand up paddler in the world, Maui HI
Leighton Nakamoto - PE Teacher, Maui, HI
Auguste Elder - Artist/Teacher, Forrest Hills, NY
... and many more ...