Definition
Xert Relative Power (XRP) estimates how much power a 75 kg reference rider (on a 9 kg bike) would need to produce to match another rider's performance at the same moment — assuming the same conditions, equipment, and aerodynamics.
XRP "weight-normalizes" power so you can compare efforts between riders — or between your own rides at different weights — more fairly.
How it’s Calculated
Xert calculates Relative Power as:
Relative Power = Power × ( 84 / mass ) ^ KGE
- Power — the rider's actual power (watts)
- 84 — the reference rider (75 kg) plus reference bike (9 kg)
- mass — the actual rider's weight (kg)
- KGE (Kilogram Exponent) — a value that changes with gradient. Higher gradients use a higher KGE.
Example: a 65 kg rider doing 300 W at KGE 0.7 → XRP ≈ 358 W. In other words, they have a ~58W advantage over a 75kg rider at that gradient.
What it Means
XRP helps you understand performance when weight matters — especially on climbs — by translating a rider's effort into an equivalent 75 kg effort.
Also note: improving “relative performance” isn’t only about weight — things like aero, rolling resistance, bike weight, and position can matter too!
XRP vs. XEP
XRP (Relative Power) and XEP (Xert Equivalent Power) sound similar but measure different things:
- XRP normalizes power across riders of different weights and gradients — useful for comparing performances between riders.
- XEP represents the average power an activity felt like across your effort — useful for gauging the intensity of a ride relative to your own capabilities.
Use XRP for cross-rider comparisons. Use XEP for ride-intensity assessment.
Where You’ll See It
- Xert analysis views where relative/normalized performance is helpful (group ride analysis)
- In Strava training summary text
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