These are the principles and sources governing the equations used to predict the resistive forces that impact a longboarder. These values, and curves, are used to estimate these forces on https://www.theblueridgeproject.com/science-of-longboards/longboard-calculator for our force estimate calculator. (Below is the data from my winning Broadway Bomb in 2024 broken down into components).
Aerodynamic drag is a major factor influencing energy expenditure in endurance longboarding, particularly as speed increases from 10 to 20 mph. Most drag forces rise with the square of velocity, while the power required to overcome aero-losses scales cubically, making it disproportionately costly at higher speeds. For endurance athletes operating near their aerobic threshold (~70–100 W), posture adjustments can shift aerodynamic drag from a manageable burden to a performance-limiting factor, while downhillers already know, aero is everything.
Clothing plays a nontrivial role in aerodynamic efficiency. Tight, streamlined apparel can reduce the drag coefficient (Cd) by minimizing turbulence around the rider’s body. In contrast, baggy or flapping garments increase frontal area and create flow separation, raising CdA significantly. For example, a short and lean rider in tight clothing may have a CdA of 0.35 m², while wearing baggy gear increases that 30%, which can translate to 10–30 more watts of drag power at 13–18 mph. Over the course of a multi-hour or 24-hour endurance race, this additional energy cost accumulates significantly and can influence pacing, fueling needs, or the ability to respond to attacks and climbs. Therefore, optimizing both posture and apparel is essential not just for maximizing speed, but for minimizing fatigue and preserving metabolic efficiency across long distances.
Unfortunately, especially at LDP pushing speeds, board and wheel aerodynamics make very litte difference compared to the person on the board. (The same can be said about weight.) It is worth noting, though, once all gains become marginal, especially in cases such as high speed downhills, aerodynamic drag is a cubed force, meaning small details such as board aerodynamics exponentially matter more than rolling resistance or weight.
At 12 mph, CFD analysis indicate the total drag on a distance skating setup, including friction from the spinning wheel's surface is about 0.7 watts.
At 35 mph, it could be approximately 5% of your total losses. That math becomes complicated as turbulance occurs.
Engineering and Industrial Aerodynamics, 104–106, 515–524. As described in figure a and b in Beaumont, the aerodynamic impact of wind as a resistive force.
Frontal areas (Ca)
o Likely in the range of 0.40–0.60 m², depending on your shoulder width, arm posture, and whether you’re carrying hydration gear
o Runners in Beaumont et al. (2021): 0.383–0.596 m²
o Casual cyclist upright: ~0.40–0.55 m²
o Would expect 0.35-0.4 to be an endurance longboarder, given the lower position and reduced turbulence.
o 0.2-0.3 m^2 for a time trial cyclist.
o Tucking riders seen in the range from 0.2-0.3 m^2.
Drag Coefficient (Cd)
o Upright runners: 0.92–0.97
o Upright recreational cyclists: 0.90–1.10
o Tucked downhill longboarders: 0.60–0.80
o CD usually sees less than 1 values when using technical fabric.
● CDA = Cd*Ca, of course.
At moderate longboarding speeds—such as 13 mph (5.81 m/s), typical of upright endurance racing—both aerodynamic drag and rolling resistance contribute significantly to total resistive power, with rolling resistance typically remaining dominant. For a rider in a relatively upright position wearing tight clothing, the estimated drag area (CdA) is approximately 0.35 m². This yields an aerodynamic power loss of about 35–42 W, depending on drafting and rider height. Meanwhile, rolling resistance—primarily influenced by urethane deflection and surface texture—can account for approximately 10-40 W, varying with wheel type and pavement quality. At 13 mph on average surfaces, rolling resistance comprises roughly 10-15% of total resistive power, with aerodynamic drag contributing 80+%.
Scholarly estimates of the coefficient of rolling resistance (Crr) for street skateboard wheels, ranges from 0.02 on rougher surfaces (Halsey, 2005). These are not translatable to longboard wheels. These tests were conducted on rough pavement with high durometer, low diameter wheels, which roll extremely inefficiently. Testing by us at BRProject indicated high-quality soft wheels such as Boa Constrictors or Caguamas can reduce rolling losses by a factor of 5x-10x over a street wheel, with CRR values ranging from 0.0025 to 0.005, which are in-line with road bike tire efficiency.
In the endurance contexts, where sustainable power outputs may be as low as 70–90 W, the importance of minimizing rolling resistance often pales in that to the importance of aerodynamic gains, but may be the easiest space to see immediate gains.
While commonly overlooked, bearing drag can contribute to overall resistance in endurance longboarding, especially during long-duration efforts. Standard 608 bearings, when spinning at around 1280 RPM (which corresponds to ~15 mph on 100 mm wheels), experience drag due to internal friction and lubrication resistance. The drag torque t converts to power using the formula:
P = t * o
Where:
● P is power in watts
● t is torque in newton-meters
● o is angular velocity in radians per second
For example, a clean and oiled bearing with a drag torque of t = 0.002 nm results in a power loss of 0.27 W per bearing, or 2.15 W total for a full set of eight (STLE, 2022). If the bearings are sealed and moderately greased, drag torque may increase to 0.005 Nm, raising losses to 0.67 W per bearing and 5.36 W total. In poor maintenance conditions—such as over-greasing, dirt intrusion, or preload misalignment—drag torque may rise to 0.010 Nm, resulting in a total loss of 10.72 W (SKF Group, 2019). Misaligned dirty bearings are potentially comparable to riding in baggy clothes versus aerodynamic clothing.
Even in suboptimal conditions, bearing drag typically represents <5% of total resistance—far lower than the 70–100 W from rolling resistance or 40–120 W from aerodynamic drag at endurance speeds (STLE, 2022). For example, an upright endurance longboarder with a drag area (CdA) of 0.52 m² may experience ~48 W of aerodynamic drag at 12 mph, increasing to ~79 W at 15 mph, and ~119 W at 18 mph—highlighting the cubic rise in aero power with speed (Beaumont & Polidori, 2025; Witte et al., 2023). However, saving even 5–10 watts by simply keeping bearings clean and lightly oiled is one of the lowest-cost, highest-return optimizations available for ultra-distance athletes, especially when combined with aero gains from posture or clothing.
For our calculations we assume a linear behavior of bearing torque losses, however at extreme speeds this becomes non-linear.
A novel aspect of my work, and a more difficult to quantify aspect of longboarding, is our losses during the “push” phase of exertion. Most people think of this in terms of how heavy a wheel feels to push, or to get up a hill. Intuitively, we think of this as the cost to accelerate a heavy wheel. Realistically, especially on a flat surface, there are not many tangible differences than a constant push where we aren't working to accelerate a wheel. As it turns out, the energy to accelerate a heavy wheel on flat, is returned in terms of angular momentum preserving our forward motion later.
To calculate acceleration, we can use the known variable of deceleration. As soon as pushing is not occurring, the system is decelerating. The energy required to push the board back up to speed results in losses due to angular momentum of the wheel, as well as linear acceleration of the body, board, and wheel. We may quantify the energy in the push phase, only attributable to the wheel, as the rider perceived “weight” of the wheel while pushing.
Using accelerometers on the board and body, as well as video footage, the proportion of push to coast phase on flat ground at a range of 10-17 mph was determined for an average longboarder. Approximate ratios of push to coast, while actively pushing without breaks at 13 mph, for example, were 0.18-0.22 seconds exerting ground force, to ~1.5 seconds swinging the leg and coasting. Efficient pushing at all speed similarly appeared to follow a 2:15, 4:15 ground contact to leg swing time and different time scales depending on gradient and speed, with extreme gradients seeing a 1:1 ratio. A driver of this consistent ratio appears to be the speed of the leg, which functions like a pendulum, where the speed (of a leg) has a relation to the frequency (of pushing), and compensation for deceleration rate, which is most impacted by gradient.
It is difficult to extrapolate this sort of data to other rides, given both gradient and speed impact the length and ratio of push coast cycle, as well as minor variations between athletes, which all impact normalized power... Meaning you need a multivariable regression, or similar mapping strategy, to estimate the push coast lengths at different scenarios, or slow motion video to quantify how things change.
During the push phase, the total system acceleration, and therefore kinetic drain, is determined as the acceleration forces required to get back up to speed in the specified time, from the speed the rider coasts to during the deceleration phase, based on the resistive losses occurring in that specified coast phase.
Wheel Inertia and Equivalent Mass
Wheel rotational inertia increases effective mass. For hollow‑cylinder approximation:
I = 0.5 · m_wheel · (r_o^2 + r_i^2) (Eq. 9)
Equivalent mass contribution per wheel is I / r_o^2. The total effective mass is:
m_eq = m_sys + Σ(I / r_o^2) (Eq. 10)
During coasting, velocity decays according to:
dv/dt = −P_total(v) / (m_eq · v) (Eq. 11)
This ODE is integrated numerically. Push energy equals change in kinetic energy plus resistive work.
References (sorry for the mess)
www.theblueridgeproject.com. (our own field wheel tests and drum tests)
PSI Urethanes. Calculating the compression/deflection of polyurethane. https://psiurethanes.com/calculating-compression-deflection
Maull, Thomas & Eichaker, Lauren & Buczek, Sean & Graham, Troy. (2020). Rolling Resistance of a Skateboard. 10.1115/IMECE2020-23910.
Pugh, L.G.C.E. (1971). The influence of wind resistance in running and walking and the mechanical efficiency of work against horizontal and vertical forces. Journal of Physiology, 213(2), 255–276.
Davies, C.T.M. (1980). Effects of wind assistance and resistance on the forward motionof a runner. Journal of Applied Physiology, 48(4), 702–709.
Bassett, D.R., et al. (1999). Determinants of distance running performance. Sports Medicine, 37, 345–359.
di Prampero, P.E., et al. (1986). Energetics of running: air resistance and running economy. Journal of Applied Physiology, 61(3), 873–878.
Witte, K., et al. (2023). Aerodynamic drag in downhill skateboarding: Measurement and simulation. Journal of Sports Engineering xxand Technology, 237(2), 85–94.
Beaumont, F., & Polidori, G. (2025). Aerodynamic challenges in running: Understanding headwind and tailwind effects. International Journal of Sports Science & Coaching, 20(3), 1259–1267. https://doi.org/10.1177/17479541251333944
SKF Group. (2019). Rolling bearing friction – Engineering reference guide.
STLE. (2022). Measuring bearing torque performance. Tribology & Lubrication Technology.
Witte, K., König, A., & Braumann, K. M. (2023). Aerodynamic drag in downhill skateboarding: Measurement and simulation. Proceedings of the Institution of Mechanical Engineers, Part P: Journal of Sports Engineering and Technology, 237(2), 85–94. https://doi.org/10.1177/17543371231153246
Beaumont, F., & Polidori, G. (2025). Aerodynamic challenges in running: Understanding headwind and tailwind effects. International Journal of Sports Science & Coaching, 20(3), 1259-1267. https://doi.org/10.1177/17479541251333944 (Original work published 2025)
