Harley-Davidson Fat Boy vs Honda CB125F

The Harley-Davidson Fat Boy (2025) and the Honda CB125F (2025) are compared with the same Moto Kıyas physics model under identical conditions: flat dry asphalt, no wind, a 75 kg rider and no passenger. The Harley-Davidson Fat Boy is a cruiser with 1,923 cc, 103.3 hp and 315 kg; the Honda CB125F is a naked bike with 124 cc, 10.7 hp and 117 kg. Power-to-weight with the rider: 264.8 hp/ton versus 55.9 hp/ton. On this measure the Harley-Davidson Fat Boy is 374% ahead.

In the simulation the Harley-Davidson Fat Boy covers 0-100 km/h (speedometer) in 3.54 s and the Honda CB125F in 21.61 s; the Harley-Davidson Fat Boy is quicker by 18.06 s. In the 60-0 km/h brake test, braking distance without the 0.3 s reaction time is 17.7 m for the Harley-Davidson Fat Boy (ABS unknown, class assumption: no ABS) and 17.3 m for the Honda CB125F (ABS unknown, class assumption: no ABS). The Honda CB125F stops 0.4 m shorter. The standard 60-0 test is used because one calculated top speed is below 110 km/h. Calculated top speed: 201 km/h (estimated from power and drag) versus 100 km/h (manufacturer claim).

All values are an estimated simulation, not road-test measurements. Technical data comes from the sources listed below; the model uses class-average calibration (no accepted model-specific road test) for the Harley-Davidson Fat Boy and model-specific parameters calibrated against published road tests for the Honda CB125F. Open the interactive app (currently in Turkish) to watch the run side by side and change the load.