How Much of a Role did Environmental Conditions Play in Hoogland’s World Record?

And what time would’ve he got if the attempt was at sea level?

I was Jeffrey Hoogland’s coach when he attempted and broke the longest standing record in cycling at the time: The 1 km time trial in a time of 55.433 seconds, set at altitude (1,887m, Aguascalientes, Mexico). Air density (which was measured to be 0.98 Kg/m3 the day he broke the WR), which lowered aerodynamic drag was the most significant factor which influenced this. The same effort at sea level, where air density is higher (typically between 1.13 - 1.22 Kg/m3), would have resulted in a slower time due to increased aerodynamic resistance. People have often asked me what would his time have been if it was at a standard sea-level attitude? Let’s find out…

In track cycling, aerodynamic drag is the dominant force opposing motion at high speeds. As velocity increases, so does the resistance from the air, which is proportional to the square of velocity. This means that at speeds exceeding 75 km/h, even small changes in air density have a significant impact on performance. The kilometre time trial is particularly sensitive to air resistance because the event is short enough that aerodynamic drag is the primary limiting factor, but long enough that fatigue and power decline also play a role in the latter phases.

This analysis breaks down how air density affected each phase of the race and estimates what Hoogland’s time would have been had he attempted the record at sea level.

Aerodynamic Influence at Different Phases of the 1km Time Trial

The aerodynamic influence of the kilometer time trial is not uniform due to the aggressive acceleration (and decelerations) in such a short period of time. Here are the key stages and the influence of aerodynamics which concludes with what he may have got should the attempt be done at sea-level.

0 - 62.5m: Minimal Aerodynamic Effect

At the start, air resistance is negligible because speed is relatively low. The primary limiting factor is inertia, meaning the rider’s ability to apply torque to the cranks is the dominant factor in this area of the event.

At this stage, the reduction in air density at altitude provides no meaningful advantage, as the forces acting against the rider are entirely mechanical, including the bike’s mass and inertia. The time required to complete this phase is dictated primarily by force application and initial acceleration.

Mechanical torque output and inertia are the main considerations, with aerodynamic resistance only becoming relevant as velocity increases.

This section of the event is one of Jeffrey’s strengths. His ability to pump out high levels of torque on such a big gear (70x15) is unmatched and he really takes advantage of lack of aerodynamic penalty to get up to speed quickly.

Verdict: The difference between a sea-level race is negligible.

62.5m - 250m: Increasing Influence of Air Density

As velocity increases beyond 45 km/h, aerodynamic drag becomes a more significant resistive force. At sea level, drag would rise exponentially with velocity due to the squared relationship in the aerodynamic drag equation. However, at altitude, with air density approximately 20 percent lower, the increase in drag is proportionally reduced.

This results in a longer period of acceleration and a higher peak velocity. Since power output is still relatively high at this stage, a reduced drag coefficient allows the rider to reach their maximum speed more efficiently. This means that at altitude, less energy is lost to aerodynamic resistance, and more of the generated power contributes to forward motion.

The key performance factors in this phase are the balance of power-to-drag and the ability to sustain acceleration for longer before reaching peak velocity.

Verdict: The time penalty is between +0.1-0.2s if done at sea-level.

250m - 750m: Maximum Aerodynamic Influence

Once the rider reaches maximum velocity, aerodynamic drag becomes the dominant resistive force. At speeds exceeding 75 km/h, rolling resistance and drivetrain losses become negligible in comparison to air resistance.

At this point, the primary benefit of altitude is realised. The reduction in air density directly reduces the power required to sustain a given velocity, meaning the rider can hold a higher average speed for the same power output.

Had this attempt been performed at sea level, the higher air density would have increased aerodynamic drag, requiring more power to sustain the same velocity. Given that a rider’s power output is limited by peak power output and/or anaerobic capacity, the higher demand at sea level would have led to earlier fatigue and a greater speed drop-off later in the effort.

The ability to sustain peak velocity for longer is one of the defining benefits of competing at altitude in events such as the one-kilometre time trial.

At altitude, Hoogland maintained a higher peak speed for longer. At sea level, a ~4% reduction in velocity would have led to a slower segment time.

Estimated time difference: +0.8s to +1.0s.

750m - 1000m: Aerodynamic Influence Decreases, Fatigue Becomes Dominant

In the final segment of the race, fatigue becomes the primary limiting factor, leading to a gradual decline in power output. Although aerodynamic drag is still present, the rider’s declining power has a greater influence on speed loss.

At sea level, the higher aerodynamic resistance would have compounded the speed loss, accelerating deceleration due to the inability to overcome drag forces. At altitude, the lower air resistance slightly delays the drop in velocity, but ultimately, the main performance determinant in this phase is fatigue resistance.

While lower aerodynamic drag slightly mitigates deceleration, it does not eliminate the fundamental limitation imposed by the rider’s energy reserves. The decrease in speed at this point is dictated more by the depletion of anaerobic energy stores than by air resistance.

At altitude, Jeffrey slowed down less due to reduced drag. At sea level, with 20 - 29% more drag, the velocity drop would be greater.

Estimated time difference: +0.6s to +0.8s for the final lap alone.

So, what would have Jeffrey’s time been if it were at sea-level?

With the estimated explainations above, at sea level, Jeffrey Hoogland’s 1 km time trial time would likely have been:

Best case scenario: 55.433 + 0.1 + 0.8 + 0.6 = 56.933

Worst case scenario: 55.433 + 0.2 + 1.0 +0.8 = 57.433

The most likely? Depends on the conditions - but if he would have done it at a fast Velodrome like Grenchen which has a typical air density of 1.14 Kg/m3 it could have been close to the 56.933 and if performed at a velodrome close to sea-level like Alkmaar where air density would be around 1.22 kg/m3, probably closer to the worst case scenario.

Either way, it would still have been pretty fast and most likely have been the sea-level world record

A comparison of cumulative time difference per half lap (125m) of Hoogland’s sea level WR vs. the previous WR by Francois Pervis in 2013 at which was performed at altitude (blue)

Then a time differential between Hoogland’s WR time vs. Pervis 2013 WR time per half lap (125m; red).