Lime is piloting a new program that allows customers of the dockless bikeshare service to donate small sums to local charities in three cities.

Starting this week, select Lime riders in Seattle, Austin, and Washington, D.C. will be notified that the “Be A Lime Hero” feature has been turned on for them in the app.

During the pilot, Lime is A/B testing two different donation models. Some riders who opt-in to the program will donate 15 cents per ride on top of the regular fare. For others, the cost of rides will be rounded up to the nearest dollar, with the difference donated to the nonprofit partner.

In Seattle, donations will go to Cascade Bicycle Club, the nation’s largest cycling nonprofit. Austin riders will have the option to donate to Austin Music Foundation and in Washington, D.C., the partner is Building Bridges Across the River.

Over time, Lime plans to add additional nonprofit organizations to the donation program. Riders will be able to choose where their donations go. Lime is hoping to learn from the three initial cities and then expand the donation program across the U.S. and Europe.