Articles

Power pacing, CdA, courses and engine validation. Written for people who take their numbers to the start line.

2026-09-03What is CdA, and why does it decide most of your bike leg time?At 37 km/h on flat road, 86% of the power you put out goes into pushing air aside. CdA is the number for how hard that pushing is, and it is the single largest source of error in a finish time prediction.

2026-09-03Course Rankings: How the Score Is Calculated100 minus four deductions: Terrain, Technical, Heat and Wind. Each one has a defined method and a cap, and the weather comes from five years of measured data for that race's calendar slot. This article lays out the formula and walks through seven courses.

2026-09-01Backtest on 60 Race Files: How Accurate Is the EngineI replayed real race power files from nine athletes through the engine. Median finish-time error is about 2%, and nine out of ten races land within ±5%. This article lays out the method, the sample, the charts, and the list of races used for validation.