Here is a great way to give back to the sport of mountain biking: Support the AZ trail building efforts by giving a small donation.
The Arizona Trail is an 800+ mile multi-use recreation trail from Mexico to Utah.
If you are in southern AZ, make a $30 donation by visiting the link above, near the bottom of this page is a button that says PayPal Donate Now. It will take you to PayPal's website where you can enter the amount ($30), be sure to input the following on item description: AZTJAMBOREEthen attend the AZ Trail Jamboree Charity Ride. Info here