Riders will need to wear both shoes, rather than carrying them in a bag or giving one to a friend, to use the ticket. The collaboration between a transport company and sportswear company is unusual, but the BVG saw it as a way of encouraging ridership.

For BVG, the Adidas coup also helps modernize its 90-year-old image. The company recently unrolled a camouflage rebranding, which it's spun out into other merchandise that includes bibs, swimming trunks and teapots.