I once went to an exhibition focused on Mexico City at P.S. 1 in Queens. The cityscape photos were revealing. You know Mexico City is built on a dry lake bed, it is completely flat and huge. HUGE! 10 million people and the sprawl goes forever, the city is like L.A. on steroids.
Back to topic, a few thousand city officials commuting by bike 12 times per year will make no significant difference at all. This gesture is purely symbolic. And given the local conditions, I'd say its downright hazardous.