He saw off Team Sunweb pair Wilco Kelderman and Jai Hindley for a win which also thrusts him into contention in the general classification.
The scheme, which is sponsored by Santander, had never previously surpassed 50,000 hires on a normal workday.
His predecessor, Boris Johnson was an enthusiastic cyclist during his eight years as mayor, frequently using his bike to travel to official events.