How the predictor works
Three simple, published models do the work. Nothing is hidden: you can check every number.
Running: Riegel’s formula
Pete Riegel’s formula predicts a time over a new distance from a recent result: T2 = T1 × (D2 / D1)^k. The classic exponent is 1.06. We use a slightly higher exponent when you train fewer hours, because endurance fades faster over longer distances when the base is smaller.
Cycling: the physics of riding
On the bike, speed comes from balancing your power against gravity, rolling resistance and air drag. We split your route into climbing, descending and flatter riding using your elevation gain, set a sustainable share of your FTP for the expected duration, and solve the speed for each part. Riding position changes your air drag.
Triathlon: three sports and two transitions
- Swim: your steady pool pace, adjusted for open water and a wetsuit.
- Bike: the same physics as above, at an intensity that leaves something for the run.
- Run: Riegel from your recent run, plus the cost of running off the bike.
- Transitions: typical times for the distance.
Using your prediction
Use the bike power as a pacing ceiling, not a target to chase early. In longer races most people lose more time by starting too hard than by starting a little easy. Then plan your fueling with the fueling calculator.
