Gaming a bike sharing algorithm

 Jacob Leshno points out this NYT story. He writes "The gist of it is that Citi bike pays to deliver bikes to stations with shortages, and someone figured they could make money by creating artificial shortages."

The Hustlers Who Make $6,000 a Month by Gaming Citi Bikes. The bike-sharing program rewards users who help redistribute bikes around New York City. A few riders have figured out how to turn that into profit.  By Christopher Maag (Christopher Maag spent several days in Midtown Manhattan running behind Bike Angels.)

"By monitoring a map of stations on Lyft’s app, they noticed that the algorithm awards points on a sliding scale based on need. Removing a bike from a completely full station: up to four points. Docking at an empty station? That’s worth up to another four. People who move at least four bikes in a 24-hour period get all their points multiplied by a factor of three.

"Lyft pays 20 cents per point. Each ride generates a maximum of 24 points. In perfect conditions, a person on a 3X streak who relocates a bike from a full dock to a completely empty one can earn as much as $4.80 for a single ride.

...

"At 10 a.m. on a Tuesday last month, seven Bike Angels descended on the docking station at Broadway and 53rd Street, across from the Ed Sullivan Theater. Each rider used his own special blue key — a reward from Citi Bike — to unlock a bike. He rode it one block east, to Seventh Avenue. He docked, ran back to Broadway, unlocked another bike and made the trip again.

"By 10:14, the crew had created an algorithmically perfect situation: One station 100 percent full, a short block from another station 100 percent empty. The timing was crucial, because every 15 minutes, Lyft’s algorithm resets, assigning new point values to every bike move.

"The clock struck 10:15. The algorithm, mistaking this manufactured setup for a true emergency, offered the maximum incentive: $4.80 for every bike returned to the Ed Sullivan Theater. The men switched direction, running east and pedaling west."