It is a "Biker Event" - that is: Bicycles, not Motorcycles :-)
Its the "2024 MoCo Epic" which is "An epic bike ride two day event in Montgomery County" at South Germantown Bike Park in Boyds, MD. The event sponsored by MORE (Mid-Atlantic Off-Road Enthusiasts) - funds raised support MORE.
Fans are welcome to stop by; band plays from 4 to 7 outside.