But now you can still protect yourself without sacrificing style.
Helmets come in way more styles than you might imagine.
There are sporty looks and then ones that are totally fashion forward.
People might not even know the hat you're wearing is a helmet, and they all meet safety standards.
"Most people find helmets to be uncomfortable and they don't like the way it fits on their head," said Seth McBurney of MetroBikes.
But he says there are plenty of options, and for all heads.
Bontrager is a good start, with a sleek sporty look.
For more visibility, there's Giro, which is well-ventilated and weighs a matter of ounces.
"As helmets increase in price they increase in ventilation, weight savings and aerodynamics," said McBurney.
A Bern model is heavier, but it's also used for winter sports like snowboarding.
There's also a Team Z colorful option by Giro.
"Team Z from the late '80's, early 90's, so you can pretend you're a professional," said McBurney.
You'll hardly look like a professional cyclist wearing one of the helmets sold at Adeline Adeline.
"I call them urban helmets. They're not meant to look sporty," said owner Julie Hirschfeld.
Her most traditional models are by Nutcase, with great colors and prints, especially for kids.
But then there are wide-brimmed options.
"What's cool about these is that you can buy one helmet and then buy extra covers for it. So if you get bored with one you can buy another cover and keep using it," said Hirschfeld.
Handpicked helmets inspired by Taro cards are one of a kind, maybe enhancing luck on a bike.
But for real city cool, there's a faux croc helmet, or an even racier one with leopard spots.
You'll be noticed for sure.
If you already have a helmet you can jazz it up with a reflective bow.
And Julie says the piece de resistance is a helmet that's faux fur.
"We've seen a huge uptick in sales of helmets," said Hirschfeld. "People obviously realize that Citi Bikes are great and it's a good idea to wear a helmet."
If you sign up for a year-long Citi Bike membership, you receive a coupon for $10 off a Bern, Bontrager, or Nutcase helmet, which are some of the ones we featured.
The prices for the helmets we showed range from about $50 to more than $200.