World Supercross at Altitude: Why Stark Were So Quick in Calgary

When World Supercross teams arrived in Calgary fresh with expectations for the first race of the 2026 season, there was one a clear objective from the Stark team – to improve their starts. Last year, the Spanish-based team did not utalise the instant torque delivered from the bike’s electric motors that would give them a competitive advantage.

But few inside the McMahon Stadium would have expected them to be so quick, as rookie Brian Hsu and Hicks in SX2 and Vince Friese and Jorge Zaragoza in SX1 powered their way to successive holeshots before ultimately being reeled in by the rest of the field.

Altitude is significant for oxygen levels

Calgary sits 1,045 metres above sea level where the air is thinner than it is at many lower-elevation race venues. That difference is significant to a high-performance supercross motorcycle. Engines need oxygen to burn fuel efficiently, and less available oxygen changes power delivery, throttle response, tuning requirements, and even how riders approach a lap.

A four-stroke supercross engine produces power by drawing air into the combustion chamber, mixing it with fuel, compressing that mixture, and igniting it. At higher altitude, atmospheric pressure falls and every intake stroke brings in fewer oxygen molecules.

If the engine received the same amount of fuel that it used near sea level, the mixture would become too rich: there would be more fuel relative to the available oxygen. A rich mixture can make an engine feel dull, soft off the bottom, hesitant under acceleration, and less crisp when a rider opens the throttle out of a corner.

How does that impact a gas-powered motor?

The first consequence is a reduction in horsepower. A naturally aspirated engine cannot fully replace the oxygen that altitude removes, so peak output declines. The exact loss depends on weather, engine specification, and calibration, but Calgary’s elevation is significant enough that World Supercross teams needed to plan for it rather than treating it lightly.

On a supercross track, where riders repeatedly accelerate from tight turns toward steep jump faces, a modest power reduction can influence rhythm sections, jump timing, and line choice. For once, the engine power and delivery was as significant as suspension set-up.

Modern fuel-injected motorcycles make altitude adjustment easier than older carbureted machines. Electronic control units use sensors and programmed fuel maps to alter fueling as air density changes. Teams may refine maps, ignition timing, throttle response, and engine-braking settings to suit Calgary’s conditions.

The goal is not maximum dyno power. Riders need a predictable, connected feel from the rear wheel, especially on slippery starts, rutted turn exits, and short run-ups to jumps.

Carbureted engines require more hands-on changes. Mechanics traditionally adjust jetting to lean the fuel mixture for thinner air, often alongside needle, pilot-circuit, and air-screw adjustments. While World Supercross machinery is predominantly modern and electronically managed, the underlying principle remains identical: fuel delivery must match the oxygen the engine can actually use.

How the altitude can impact engine temperature

Calgary’s conditions were incredibly mixed. The race day was warm before a storm came midway into the Main Event and that humidity can also contribute to a performance drop because water vapour displaces some oxygen in the intake charge.

Cooling is another consideration, though altitude does not automatically mean an engine will run hotter. Reduced power can lower heat generation as aggressive tuning, sustained high revs, deep dirt, and reduced airflow in stadium sections can still strain cooling systems.

For riders, too Calgary’s thin air was another obstacle to overcome. Exertion at altitude meant recovery time in between races was longer as their bodies sought more oxygen, making it physically tougher than a race at sea level.

Ultimately, the speed of the Stark’s caught the attention, but it was not so much about their power advantage, which is limited to the same as a 450cc or 250cc gas-powered bike – depending on the class they are competing, but it was about how the altitude had impacted the performance of the engines of their rivals.