Longboard skaters harness the laws of physics to generate flow. And while the rider might not always know the exact principles at play, they can feel those equations pushing and pulling them forward as they “turn” through S-curves.
From an engineering perspective this is a dynamics problem best explained with force vector diagrams. A deep understanding of the rider technique, combined with the longboard truck set-up 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 at the same time, on any kind of longboard. Minimizing drag while optimizing thrust is highly dependent on the longboard's steering geometry and the rider's technique, all of which are explained below.
First let's define some 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.
Here we consider three “center of turning” categories of longboards; Centered, Back Foot and Rear Axle. We refer to three styles of riding; Carving, Surfskating and Pumping.
By illustrating force vector diagrams, this presentation explains how the rider creates forward force, without foot pushing. Forward force vectors are known as thrust. Backward force vectors are known as drag. Further, information is provided which explains why the center of turning is critical for different riding styles.
With proper technique, skilled riders can generate forward thrust (pump) on any type of longboard, but certain set-ups work better for different riding styles.
The Hamboards HST Truck System has components that are interchangeable, so any given deck can be built with different configurations for different riding styles. There are four different kingpin pivot angles 0°, 20°, 40° and 55° – all of which can be combined to match any riding style.
Centered Longboards have equal turning in the front and rear, with the center of turning located at the center of the wheelbase.
Back Foot Longboards have more turn in the front than the rear and the center of turning is 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.
Now let’s address the characteristics of Carving, Surfscating, and Long-Distance Pumping.
Carving, a term borrowed from surfing, is the original means of propulsion in longboarding, in which a rider uses a Centered Longboard, standing over the middle of the board and making sequential S-turns while the front and rear axles travel a virtually identical path, similar to snowboarding.
Here's World Champion Surfer Cory Lopez Longboard Carving on a Hamboards Twisted Fin with HST 40/40 trucks, creating forward thrust and climbing up a hill. Notice his front hand stays over his front hip allowing him to twist his body core, creating lateral force with both his front and rear feet through powerful S-Curves. Cory is generating roughly equal forward thrust vectors with both the front and rear wheels. It's an aerobic method that requires high skill & fitness.
Cory is powering his rear foot opposite to his front foot causing him to feel equal front pull and rear push equally and at the same time. Cory uses this same technique on his shortboard surfboard, to generate thrust and gain more speed on a wave. Here's a magical full video with Cory Lopez and his kids
Surfskating is a variation of longboarding, (a blend of Carving and Pumping) in which a rider uses a rear foot longboard, standing over the middle of the board and making sequential S-turns. The front axle travels a wider path than the rear axle allowing the rider to create deep carves and a forward force vector, similar to surfing. .
Here is Hunter Joslin, the iconic surfer and founder of IndoBoard. He is Surfskating on a Hamboards Burst with HST 40/20 trucks and accelerating along a flat. Notice his front hand stays over his front knee allowing him to twist his body core and create lateral force with both his front and rear feet through powerful S-Curves. This, too, requires substantial power, and requires skill & fitness.
Hunter is mostly steering with his front foot and powerfully driving his rear foot. Even though he's able to generate a much larger force vector by only moving his front foot, Hunter's pushing harder with his back foot, resulting in nearly equal thrust (front pull) and (rear push). Here's an amazing full conversation with Hunter Joslin teaching us all about balance and flow.
Pumping is a special case of longboarding, in which a rider uses a rear axle longboard, standing mostly over the front of the deck and making rapid sequential S-turns. The front axle travels a wide path and the rear axle travels a very narrow path allowing the rider to maximize forward force vector. It is often called Long Distance Pumping or LDP.
Here's world class Long Distance Pumping athlete Landy Cook Longboard Pumping on a prototype 60in carbon fiber reinforced, foam core board with HST 55/ZR0 trucks and efficiently accelerating on a flat. Notice both his feet are 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 is creating only front thrust (pull) and zero rear thrust (push). It's powerful, highly efficient and can be mastered with good rhythm.
Landy is only feeling front pull and it's very efficient. Pumping has become a quintessential skill for endurance distance skating.
Creating forward thrust comes in pulses, forcing the board forward at just the right place during sequential S-curves with synchronization and rhythm.
For surfskating, (diagram above) the rider is advised to push much harder on their rear foot, because they have less "angle" to work with. This is why surfskating coaches encourage riders to push much harder with their rear foot, but most new riders tend to wiggle the front truck.
The reader can easily find YouTube videos of swivel surf skaters. (Most "surf skate trucks" swivel in the front, the HST truck system does not. The HST leans and turns, but it does not swivel.) You might notice some novices keeping their legs mostly straight while windmilling their arms, flailing around or even riding with their hips pointed forward or holding a hot drink in one hand (true). Front swivel truck surfskates allow upper body twisting to result in forward thrust, but HST Trucks are not on a swivel and they don't. You have to get your entire body synchronized while riding longboards with HST Trucks. Riders just can't "cheat" them. The rider needs to be in balance, have rhythm and synchronize their center of gravity with the board to achieve flow, whether Carving, Surfskating (properly) or Pumping. (Don Sandusky)
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 benefiting the rider when they surf, snowboard, slalom ski etc... (Hunter Joslin) Watch Here.
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.
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, provided it has a high degree of turning. It all 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 set-up.
Centered Longboards can be pumped to maximize forward thrust, pulling from the front and pushing from the rear, and it takes a lot of energy and skill from the rider. Most traditional Hamboards are Centered Longboards.
Back Foot Longboards can have a comfortable combination of carving and pumping, provided the rider has proper technique. Most surfskates are some variety of back foot longboards and are generally easy 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 by pumping. Optimizing front turning angle, and a longer deck yield the best forward thrust vectors, but the turning diameter can be quite long. All Hamboards decks can be converted to Rear Axle Longboards.
Hamboards HST Trucks are interchangeable and modular. HST Trucks can be set-up for Centered, Back Foot and Rear Axle longboards with minimal effort, allowing the rider to adapt their board to their preferred riding style, Carving, Surfskating and Pumping. It all works.
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
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 Sout - 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 ...