How does the e-bike range calculator work?
Most online calculators multiply a few coefficients and pull a number out of thin air. Ours computes the real mechanical work the system (rider + motor) must do to cover the route:
- Rolling resistance:
W = C_rr × m × g × d— where C_rr depends on surface (tarmac 0.005, MTB trail 0.035, mud 0.075), m is system mass, d is distance in meters. - Climbing:
W = m × g × h— pure physics, potential energy. In mountains it's usually the biggest chunk of usage. - Drivetrain efficiency: motors are 78-88% efficient (model-dependent), the controller + cabling + voltage add another ~5% losses. Plus temperature and battery age.
- Rider input:the more you pedal, the less the motor draws. Assist mode sets the motor's share of total work.
Note: air drag is included (CdA = 0.55 standard MTB attack position, ρ = 1.225 kg/m³). At 18-25 km/h MTB usually has only ~3-8% share of total work (less than climbing and rolling). At 40+ km/h on a road e-bike it dominates. You can override CdA in the Details section.