Some of the disparities are cultural in the making—and don’t make a ton of sense. On the streets, men disproportionately ride, meaning cycling is masculine, right? Not really. Packs of cyclists are derisively referred to as “MAMILS,” as in Middle-Aged Men in Lycra. Meanwhile, step into a spin class, and you may likely see only women clipping in. Context, it turns out, is everything.

More broadly, exercise has become a luxury good. It was the Yuppies who made marathoning and high-end road bicycles so popular. Today, people are just as likely to commute by bicycle in households that have more than $200,000 in income as they are in households…

Read the full article at TIME.COM