About Spokiva

Spokiva was founded to give cyclists, coaches, and enthusiasts a free, high-precision toolkit for analyzing the physics of riding. We believe that understanding the science behind cycling performance should be accessible to everyone, without barriers or paywalls.

The Physics of Speed and Power

Our calculators use the standard mathematical equations of cycling physics. When you ride, you overcome several resisting forces:

• Aerodynamic Drag: The force required to push through the air. This scales with the square of your speed, and the power required to overcome it scales with the cube. This is why small speed increases require significantly more effort.
• Rolling Resistance: The friction between your tyres and the road surface, determined by tyre design, pressure, and total system weight.
• Gravity: The gravitational pull you fight when climbing. On gradients steeper than 4%, gravity quickly becomes the dominant force.
• Drivetrain Loss: The mechanical energy lost through your chain, sprockets, and bearings, typically modeled as a small constant percentage (around 3-5%).

By modeling these forces together, our calculators can predict speed from power (or power from speed) with high accuracy, matching real-world results when input variables are set honestly.

VO₂ Max Estimation

VO₂ max is the maximum rate at which your body can consume oxygen during intense exercise. While a metabolic cart test in a sports laboratory is the gold standard, Spokiva offers two reliable field estimates:

1. FTP / Power Method: Converts your Functional Threshold Power (FTP) to Maximal Aerobic Power (MAP) and applies the ACSM cycling equation.
2. Heart Rate Ratio Method (Uth Formula): Estimates VO₂ max based on the ratio between your maximum heart rate and resting heart rate.

Our Guiding Principles

100% Free

There are no premium tiers, no locked features, and no ads. Spokiva is free to use for everyone, forever.

Privacy First

We do not collect, upload, or store the numbers you enter. Your weight, threshold power, heart rate, and gearing setups remain entirely in your browser. All computations are run locally on your device.

Accuracy & Simplicity

We focus on providing clean, fast, and responsive user interfaces powered by standard physical models. We keep the site lightweight so you can quickly model a ride or check a gear ratio on your phone mid-ride or at home.