Soho to Dalston PB

who's good at maths?

here's a question:

Hauska brings his bike to the Herne Hill track and copies his ride (21mph for 11k), 11k is about 24 laps of the track, if the resting bunch are going around on the blue line at 24mph, how many laps before they overtake him?
#

1 miles = 1.609344 KM

Hauska goes at 34 KMph OR 0.57 Km per minute
Rob goes at 38.6 KMph OR 0.64 Km per minute

Hauska
1km takes 105 seconds
1 lap takes 47.6 seconds

Rob
1km takes 93 seconds
1 lap takes 42 seconds

Rob gains 5.6 seconds no each lap so will over take halfway through the 9th lap (8.5)