Time Trial Prediction Calculator

Work out time trial prediction instantly with clear inputs, formula shown and shareable results.

About Time Trial Prediction Calculator

Time trials scale like endurance events but with a smaller fade, so a Riegel-style exponent of about 1.04 fits cycling better than the 1.06 used for running. The lower exponent reflects that a cyclist's aerodynamic position and steady effort make the drop-off with distance gentler than in running.

Formulas

Prediction

t2 = t1 x (d2 / d1) ^ 1.04

Speed

speed = target distance / predicted time in hours

Worked example

With the default values below, Time Trial Prediction Calculator returns Predicted time of 65.80. Change any input above and every figure here is recalculated in your browser.

Inputs used

Distance already time trialledminimum 0.1 km: 20 km
Time for that distanceminimum 0.1 min: 32 min
Target time trial distanceminimum 0.1 km: 40 km

Results

Predicted time: 65.80 min
Predicted time in hours, minutes and seconds: 1:05:48
Predicted average speed: 36.475 km/h
Speed lost versus the shorter effort: 2.73%

Step by step

1Values used
2Prediction
3Speed
4Predicted time= 65.80 min
5Predicted time in hours, minutes and seconds= 1:05:48
6Predicted average speed= 36.475 km/h
7Speed lost versus the shorter effort= 2.73

Assumptions and limits

The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is the Time Trial Prediction figure worked out?

t2 = t1 x (d2 / d1) ^ 1.04. Time trials scale like endurance events but with a smaller fade, so a Riegel-style exponent of about 1.04 fits cycling better than the 1.06 used for running.

Why does this matter?

The lower exponent reflects that a cyclist's aerodynamic position and steady effort make the drop-off with distance gentler than in running.

What do I need to enter?

Enter distance already time trialled, time for that distance, target time trial distance. The defaults shown are a realistic worked example — swap in your own figures to get a result you can use.