It's doing 4km/h with 14 cm legs. If that scales linearly to human size legs, say 100 cm, it'll be doing 28 km/h. For comparison, Usain Bolt can sprint at ~45

It's doing 4km/h with 14 cm legs. If that scales linearly to human size legs, say 100 cm, it'll be doing 28 km/h. For comparison, Usain Bolt can sprint at ~45 km/h for 10 seconds, and pro marathoners struggle to hit 20 km/h sustained.