Cycling Speed Calculator
Enter your watts and setup to get your speed. Then switch to the Aero-Weight ROI tab to see exactly how many minutes an aero helmet, aero wheels, or losing 2 kg saves over your race distance, ranked by time saved and cost per minute.
Uses the validated Martin (1998) road-cycling power model. We call the upgrade comparison the Aero-Weight Time-Cost Model.
Enter your watts and setup above to see your speed.
Full CdA model?
Cycling Aero Calculator
Model your exact position, wheels, helmet, and skinsuit with a per-component breakdown and yaw sweep.
Biomechanics?
Crank Length Calculator
Get the saddle-height offset and aero gains from switching crank length on your road or TT bike.
Cycling speed calculator FAQ
How fast can I cycle at 200 watts?
At 200 watts, a 75 kg rider on a road bike (CdA 0.32, Crr 0.004) on flat ground in still air covers approximately 29 to 31 km/h (18 to 19 mph). The exact figure depends heavily on aerodynamics and rolling resistance. Add 10% headwind or switch to a gravel position and you can lose 2 to 3 km/h at the same power. This calculator uses the validated Martin et al. road-cycling power balance model to give you a precise answer for your exact setup.
Is losing weight or buying aero wheels faster?
At typical road-cycling speeds of 30 to 40 km/h, aerodynamic upgrades beat weight savings almost every time on flat or rolling terrain. Deep-section aero wheels (roughly -0.015 CdA) typically save 2 to 4 minutes over 100 km compared to 1 to 2 minutes for losing 2 kg. On steep climbs (6% or more), weight matters much more and the equation shifts. The Aero-Weight ROI table in this calculator ranks every upgrade by minutes saved so you can see exactly which investment pays off for your race.
What is a good CdA for a road cyclist?
A typical recreational road cyclist in a standard drop-bar position has a CdA of around 0.32 to 0.36. A strong club racer in a good road position sits around 0.28 to 0.32. A dedicated time trialist or triathlete in full aero position with aero bars, aero helmet, and skinsuit can reach 0.20 to 0.24. Each 0.01 reduction in CdA saves roughly 10 to 15 watts at 40 km/h, which translates to meaningful time savings over race distances.
How much faster are aero wheels on a 100-mile ride?
At 35 km/h (22 mph) average speed on flat terrain, switching from box-section alloy wheels to 60 mm deep-section carbon clinchers (approximately -0.015 CdA) saves around 3 to 5 minutes over 160 km (100 miles). Savings scale with speed: faster riders benefit more from aero gains. In a crosswind, deeper wheels can slow you down relative to a moderate-depth rim, so the net benefit varies by course and conditions.
What is Crr (rolling resistance coefficient)?
Crr is the dimensionless ratio of rolling resistance force to normal load. Road tires on smooth pavement run Crr of 0.003 to 0.005. Gravel tires on mixed surfaces are 0.006 to 0.010. High-quality road racing tires (latex tubes, smooth asphalt) can reach Crr of 0.002 to 0.003. Lower Crr means less power lost to tire deformation and road friction. Unlike aerodynamics, rolling resistance savings are constant regardless of speed, so they matter proportionally more at lower speeds.
See also: how much drafting saves in cycling.
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