$6 entry fee for White Tanks Regional Park
This track often has races here so be sure to check the schedule to make sure there is not an event going on that day.
This is a good one-way loop with several options to make it shorter as there are several connections that cut across other parts of the loop to make for a shorter ride (ride this trail clockwise).
The trail starts as doubletrack, but don't get discouraged. You'll take a left where there are signs for the technical loop (don't worry it's not that hard.) The rest of the trail will take you across several washes, over some small obstacles, and uphill with a few switchbacks. At this point get ready for a fun little downhill full of loose rocks and some small drops. Continue riding back out onto the flats and get back to the parking lot.
Probably the best cross county trail at White Tanks Mountain Park.