For 24 hours on Monday, April 22, riders who don't have an annual Capital BikeShare membership can use one of the company's bikes for up to 30 minutes. Find out how to do it.

Capital BikeShare is marking Earth Day with free rides around the D.C. metro area.

For 24 hours on April 22, riders who don’t have an annual Capital BikeShare membership can use one of the company’s bikes for up to 30 minutes.

To get the free bike for a half an hour, riders can download the Capital BikeShare app and enter the promo code EARTHDAY19. Trips over 30 minutes will start racking up usage fees.

Despite the proliferation of scooters and dockless bikes around here, Capital BikeShare is holding its own.

Capital BikeShare said so far this year, riders have completed nearly 700,000 trips. Capital BikeShare has more than 530 docking stations throughout the metro area with 4,3000 bikes.

For more than the occasional user, Capital BikeShare offers an $85 annual membership, which includes 365 days of unlimited 30-minute rides. One-day and three-day passes, popular with tourists and visitors, are $8 and $17, respectively.

Lyft bought Motivate, the company that operates Capital BikeShare, New York City’s Citi Bike and bike-sharing programs in several other cities last summer.