This is a counter clockwise loop leaving from the main parking lot for Point Pinole Regional Park. This loop consists of mostly fire road, but has a bit of singletrack on the west side of the park during the first mile or so.
Following along the west coast side (some nice views of the bay) you continue on towards the pier. Ride out to the end and take a break while you enjoy views of the north bay. There are usually people fishing out near the end of the pier. Come back down the pier and follow along the east side of the loop that spits you out at a small beach at the end of mile four.
You'll ride through some tall trees (lots of eucalyptus around) on your way out. Head back out from the way you came into the beach and follow left back to the main parking lot. You'll pass by picnic sites and playgrounds as you get closer to the lot. You'll also get to ride an overpass bridge where freight trains and Amtrak sometimes travel through. Very easy ride without much ascent/descent. It's a little narrow on the singletrack by the western side, but it's not anything tough (unless you're bringing small children along). This loop is derived from several park trail options available. Trails within the park are much more laid back and family friendly. This loop will give you pretty much everything the park has to offer in terms of terrain and scenery.