Bike Pacing Calculator — how fast will you ride your course?
On the bike you don't control speed — you control power. How fast you end up is decided by physics: your weight, your aerodynamic drag, rolling resistance and above all the course's elevation profile. Upload your route as a GPX and see how you'd ride it at a target power.
The calculator solves, for every kilometre of your course, the resulting speed from your target power — using the same physical basis professional tools rely on. You get an estimated total time, the speed for each segment, and a feel for how strongly position and weight move your time. Everything runs in your browser; your GPX file is never uploaded anywhere.
| km | Gradient | Speed | Time |
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Model estimate, not a prediction: the distribution across the course (where fast, where slow) is robust. The absolute time depends heavily on aerodynamic drag (CdA) and is usually higher in real races because of corners, turnarounds, wind and fluctuating power. Use the number for planning, not as a guarantee.
Why target power decides almost everything
Running, you steer directly through pace. On the bike it's different: you pedal at a certain power, and how fast that makes you follows from the balance of forces. Working against you are three resistances — gravity on the climb, the tyres' rolling resistance and aerodynamic drag. The calculator solves this balance for each segment: given power, given gradient, find the speed.
The single most important factor at pace is aerodynamic drag, expressed as CdA. Because it grows with the square of speed, it consumes most of your power on flat, fast courses. That's why riding position often matters more than a few extra watts — a point the calculator shows you directly if you pick an upright position.
How to use the calculator
Upload a GPX of your race course or a training loop — most bike computers and platforms export it. Enter your target power (if you know your FTP, 70–85 % is a good starting point for a longer ride), your system weight and your riding position. The calculator then shows the estimated time, the elevation profile and the speed kilometre by kilometre.
Play with the values. Add 20 watts and see how little time it saves on a windy, flat course. Then switch from upright to aero — often the time gain is larger. That feel for the levers is the real value of the calculator.
From constant power to a real pacing plan
This calculator uses a constant target power — it shows how that one power translates into speed across the course. The real pacing optimum looks different: on the climb it pays to push a little harder (that's where you lose the most time), on the descent a little less (gravity works there anyway). This variable power distribution — together with wind and weather correction for race day — is part of the advanced pacing plan in the Yama app. This calculator gives you the solid foundation; the app turns it into a race-day plan.
The full pacing plan in Yama
Variable power distribution, wind and weather correction, and a race-day plan for your events — built on the same model as this calculator.
Try Yama for freeFrequently asked questions
How accurate is the estimated bike time?
The relative distribution — where you're fast and where you're slow — is robust. The absolute total time depends heavily on your aerodynamic drag; treat it as a model estimate. Real races are usually a bit slower because of corners, turnarounds, wind and fluctuating power.
What is CdA and why does it matter so much?
CdA is your effective aerodynamic drag. It dominates bike time above roughly 30 km/h. Reference values: time-trial position around 0.24, drops around 0.30, upright around 0.32.
Do I need a power meter?
No. Enter any target power — if you know your FTP, 70–85 % is a good guide. Without a power meter, try values and watch how time and speed respond.
Why would power differ uphill versus downhill?
In this calculator you ride at constant power. The pacing gain from variable distribution (harder uphill, easier downhill) is part of the advanced plan in the Yama app.