Apply your own off-bike pace slowdown to a fresh run or calculate the measured slowdown from matched fresh and brick-run efforts.
How the Brick-Pace Calculation Works
Expected mode multiplies fresh pace by one plus a slowdown percentage supplied by the athlete. Calibration mode reverses the comparison: it divides a matched brick-run pace by fresh pace and reports the percentage increase in time per kilometer or mile.
| Fresh pace | Brick pace | Pace slowdown | Speed loss |
|---|---|---|---|
| 5:00/km | 5:15/km | 5.000% | 4.762% |
| 5:00/km | 5:24/km | 8.000% | 7.407% |
| 5:00/km | 5:30/km | 10.000% | 9.091% |
Why the Percentages Differ
Pace measures time per distance, while speed measures distance per time. They are reciprocals. An 8% increase in pace time therefore produces about a 7.407% loss of speed, not an 8% loss.
Worked Example
A fresh pace of 5:00 per kilometer with an athlete-entered 8% penalty becomes 5:24 per kilometer. Across 10 kilometers, that is 54:00. Fresh speed is 12 km/h and brick speed is about 11.111 km/h.
Calibrating With a Matched Test
A fresh 8:00 per mile and brick 8:40 per mile differ by 40 seconds. Dividing 520 seconds by 480 seconds gives an 8.333% pace slowdown and a 7.692% speed loss. Repeat the comparison on similar terrain and at similar effort to build a personal range.
Using the Sensitivity Rows
The five sensitivity rows hold fresh pace constant and vary the entered or measured slowdown by two percentage points in one-point steps. They show how a plausible personal range changes pace before a goal is committed. Treat the rows as scenarios rather than probability bands, and choose the range from repeated comparable workouts.
Research Context and Limitations
One original study of nine well-trained triathletes reported roughly 7% to 9% slower 3 km run times after the tested cycling cadence conditions than during an isolated run. That small, protocol-specific observation is not a universal default. Cycling intensity, duration, cadence, fueling, heat, terrain, run distance, and athlete experience can all change the response.
Sources
Bernard et al., Effect of Cycling Cadence on Subsequent 3 km Running Performance in Well Trained Triathletes, 2003.