How segments work and reading the effort table (incl. Running Effectiveness for Stryd).
A segment is a fixed stretch of road/trail/pool you define once from an activity's GPS track. Every activity that traverses it is auto-matched, so you can compare like-for-like efforts over time, terrain held constant.
Each effort shows time, distance, speed/pace, power, W/kg, NP, HR, match quality and the source activity. Click a column to sort. Because the terrain is identical, differences between efforts are real, fitness, fatigue, pacing, or kit.
For Stryd-powered run efforts an RE column shows Running Effectiveness (speed ÷ W/kg). Comparing RE on the same segment is the fairest way to test shoes: the shoe worn shows under each effort. RE is shown only for Stryd efforts; non-Stryd power isn't comparable, so those rows are left blank. See Run power: Stryd vs Garmin.
On bike segments the effort table includes a rough CdA estimate, back-solved from power, speed and grade on that effort. It's a quick, zero-effort way to spot a change in aerodynamics between rides on the same stretch. Treat it as a ballpark: it assumes still air and a fixed rolling resistance, so wind and surface move it around. For a number you can act on, use the CdA calculator; better still, run a dedicated aero CdA field test (an out-and-back, or a Chung "virtual elevation" protocol) in steady, low-wind conditions.
Tick the checkbox on two or more efforts and press Compare selected. A side-by-side matrix opens: one column per effort (newest first, with the shoe worn shown in each column header) and one row per metric. The best value in each row is highlighted, so a kit or fitness difference jumps out. Metrics are grouped:
This is the fairest shoe test on Grepiac: terrain is held constant by the segment, the shoe is labelled per column, and the environment block tells you how much of any difference was the course or the wind rather than the shoe. Vertical oscillation is shown in mm.
Whether other athletes' efforts appear is controlled per team by the segment-effort sharing toggle (separate from segment visibility).
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