where to take a kid in around concord to practice?

so a little backstory first. my son was super excited to try dirt biking when he got his bike about a year ago. rode it for 10 mins and was done with it, wanted nothing to do with it at all. so the bike sat in the shed for almost a year and this morning after watching x games (of course) he decides to try out the bike again. wow what a year makes, he can reach the ground now and wants to ride like crazy.

now here's the problem, he rode in the back yard this morning but it's just to small to teach him how to properly ride in. Id like to find a nice open space pretty close to concord where i can take him out to practice, and possibly jump on my mini as well to just cruise around with him. I like going to carnagie and hollister but currently with my body the way it is it kills me to go out there and not be able to ride the yz250 and since he's only good for about 20 mins at a time it owuld be a big waste of gas and time to go out to either place, I have thought of possibly going out and camping at hollister but im not sure if my wife and other son would enjoy it.

anyone know of a large field or place near concord where a kid can go and practice? if you do go ahead and pm me so your spot doesnt get blown up

other ideas are good too

thanks dirty guys and gals

I've seen little kids riding out here before...definitely of questionable legality, but probably not a big deal to go for a bit to practice...

http://maps.google.com/maps?f=q&hl=...437,-122.066989&spn=0.003685,0.00442&t=h&z=18