Riding a bicycle has a couple clear advantages: It strengthens your heart and muscles and is environmentally friendly, reducing carbon emissions from urban transportation.

And in the United States, that means the number of bikers on the road has doubled between 2001 to 2009, with the number of Americans biking to work spiking by by 60 percent over the past decade.

This biking bonanza, however, doesn’t come without some growing pains. According to a study released Thursday in the journal Injury Prevention, the number of emergency department visits and hospital admissions because of adult bicycle accidents has increased dramatically over the last 17 years. These injuries — both fatal and non-fatal — amount to $237 billion worth of accidents.

“In the past, many bicycle accidents stemmed from non-street incidents,” Thomas Gaither, medical student at the University of California, San Francisco, and co-author of the paper, said in a statement. “But now, street crashes with motor vehicles represent a greater proportion of the total costs. These crashes, which primarily occur with motor vehicles, increase the velocity of the crash impact, and as a result, the severity of the injury.”

Gaither and his team analyzed nearly two decades of non-fatal bicycle accident data from the National Electronic Injury Surveillance System, the Consumer Product Safety Commission’s Injury Cost Model, as well as fatal accident data from the National Vital Statistics System.

Cities with bike friendly lanes could help drop injury rates.

They found that between 1997 and 2013 there were 3.8 million non-fatal adult bicycles injuries and nearly 9,839 deaths. In 2013 alone, the costs from bicycle accidents amounted to approximately $24.4 billion — double the expense of all other “occupational illnesses” combined that year.

Older men in particular suffered the most. In 1998, 26 percent of bike accidents involved men who were 45-years-old and up; that number doubled to 54 percent by 2013.

Why are bike accidents increasingly common? The researchers blame more commuters cycling to work and more dangerous vehicular traffic, arguing that while the benefits of biking outweigh the risks, it’s clear that cities should invest in safer cycling infrastructure. While the United States has 4 million miles or roads, less than 200 of those miles are protected bike lanes. That’s a shame, because other studies have found that when cities have protected bike lanes, the safety rates for cyclists improve by 171 percent.

“Many of these injuries are preventable with safer roads,” said lead author Dr. Benjamin Breyer in a statement. “As our cities become more dense and we look for ways to promote active commuting to benefit health and environment, we need to invest long term into our bicycling infrastructure.”

Photos via Wikipedia Commons, Giphy