Calculate cycling speed from distance and time, or estimate speed based on power, weight, terrain, and wind. Convert between mph and km/h.
Knowing your cycling speed helps you plan routes, track fitness progress, and set realistic goals for events. Average cycling speed varies enormously depending on fitness level, bike type, terrain, wind conditions, and riding position. A recreational cyclist might average 15-20 km/h, while a competitive amateur holds 28-33 km/h, and professional riders sustain 40+ km/h in time trials.
This calculator offers two modes. The simple mode computes speed from distance and time — perfect for analyzing completed rides. The advanced mode estimates your potential speed based on power output, rider weight, bike weight, aerodynamic position, gradient, and wind speed. This physics-based approach uses the fundamental cycling power equation to predict speed under any conditions.
Understanding what affects your speed helps you make smarter equipment and training decisions. Aerodynamic drag accounts for about 80% of resistance on flat ground above 25 km/h, which is why time trial positions and deep-section wheels make such a large difference. Below 15 km/h, rolling resistance dominates, making tire choice and pressure more important.
This calculator helps you predict finishing times, plan pacing strategies, understand the physics of cycling speed, and make informed equipment choices by quantifying the impact of aerodynamics, weight, and terrain. Keep these notes focused on your operational context. Tie the context to the calculator’s intended domain. Use this clarification to avoid ambiguous interpretation. Align this note with review checkpoints.
Simple: Speed = Distance / Time. Advanced: Power = Gravity Force + Rolling Resistance + Aero Drag. Where Gravity = Mass × g × sin(gradient), Rolling = Crr × Mass × g × cos(gradient), Aero Drag = 0.5 × CdA × air_density × velocity². Speed is solved iteratively from the power equation.
Result: 33.2 km/h (20.6 mph)
A 75 kg rider producing 200 watts on a flat road with no wind and a standard road bike position (CdA = 0.35) will travel at approximately 33.2 km/h. At this speed, aerodynamic drag consumes about 160W (80%) of the total power.
Cycling speed is determined by the balance between propulsive power and resistive forces. On flat ground, three forces resist motion: aerodynamic drag (proportional to velocity cubed), rolling resistance (roughly constant), and drivetrain friction (typically 2-4% of power). Because aero drag dominates at higher speeds, doubling your speed requires roughly eight times the power — this is why 40 km/h feels dramatically harder than 30 km/h.
On climbs, the power equation shifts dramatically. At 8% gradient and 15 km/h, gravity accounts for about 85% of total resistance, making rider weight the dominant factor. A 5 kg difference between two riders translates to roughly 1 km/h on steep climbs — significant in a race. This is why professional climbers obsess over weight, while time trialists focus purely on aerodynamics.
Wind, temperature, altitude, and road surface all affect actual speed. Altitude reduces air density (good for aerodynamics) but also reduces the power output of most riders (bad for everything). A ride at 2,000m elevation has about 20% less air resistance but also typically 5-10% less rider power. temperature changes of 20°C shift air density by about 7%, which translates to roughly 0.5 km/h at race speeds.
For recreational cyclists, 16-20 km/h is typical. Fit club riders average 25-30 km/h. Competitive amateurs sustain 30-35 km/h. These are solo speeds on mixed terrain with some stops.
A 15 km/h headwind can reduce your speed by 5-8 km/h at the same power output. Wind has a cubic relationship with speed, so the faster you go, the more devastating a headwind becomes.
Weight matters very little on flat, smooth roads. It primarily affects climbing and acceleration. A 1 kg weight savings on flat ground at 30 km/h saves less than 0.1 km/h. Focus on aerodynamics instead.
Moving from an upright position (CdA ~0.55) to drops (CdA ~0.35) can increase speed by 3-4 km/h at the same power. Full time trial position (CdA ~0.22) adds another 3-5 km/h.
GPS speeds include stops, coasting, and GPS error. Average moving speed is usually 5-15% higher than overall average. Strava shows both metrics for comparison.
Rough roads can increase rolling resistance by 20-50% compared to smooth tarmac. This means 1-3 km/h speed difference at the same power on rough chip-seal versus smooth pavement.