About a year ago, our city joined the ranks of places like London and New York and Chattanooga and got a bike share—you know, those docking stations downtown that are filled with bikes you can rent for short periods of time.

Monthly passes typically cost $20, BUT because it is (apparently?) “Bike Month,” Metro is offering them for free. Here’s how to get one: Sign up online and use the promo code BIKEMONTH17 at checkout. You can choose to have a new bike share TAP card mailed to you, or you can add it to a Metro TAP card you already have.

RELATED: Everything You Need to Know About L.A.’s New Bike Share

Now, here’s the important part. Just because the pass is free doesn’t mean you get unlimited access to the bikes. All trips for 30 minutes or less (between when you check out a bike and when you dock it at another station) won’t cost you anything, but trips longer than that will cost $1.75 per half hour.

Also, note that after your first free month, you’ll be charged $20 for every month thereafter unless you switch off auto-renewing. To do that, login to your account on the Metro Bike website, and uncheck the auto-renewing button in the bottom right corner of the page.

Thomas Harlander is a staff writer at Los Angeles magazine. You can follow him on Twitter and Instagram. He recently wrote: This Might Be the Best Argument for More Bike Lanes