Hi. Sorry I can't help you out with a ride guide. I'm new to North Andover, and still trying to get an idea of all the best places to ride. A previous post of mine on here fell on deaf ears. I won't let that happen to you, though. Here's where I ride:
Boxford State Forest's main entrance is just within a corner of North Andover. It's my favorite riding area here, that I've found so far. Caveat: I'm not sure the numbered intersections are perfectly aligned with what's on the state map. But, otherwise, there's some really nice riding here. Challenges, without being crazy technical. There's also other preserved land around BSF, and my last ride there I found a dream-like strip of singletrack, fern-lined, pine-needle-covered, swoopy and smooth. It was somewhere in the central northern section, and I couldn't find it on the BSF map. May have been a Boxford Trails Assoc. trail. Marked on the road with a white diamond, green arrow blaze.
Also, just in West Boxford is a small place with good terrain called Wildcat Forest. All singletrack, technically similar to the terrain of BSF (my favored level of difficulty). Small, quiet area, without many folks. Easy to make a couple loops. Find a PDF map by searching for the Boxford Trails Assoc. Site.
Harold Parker is well-known, and I've ridden there many times. For me, much of the singletrack is too rocky/technical to maintain enough speed to be as enjoyable as these other places. Others love the challenge.
The previous commenter is right about Ward Hill. I've never been there, but it's on my to-do list. My take on the place (anyone please correct me) is that it's not super technical, but very pretty. The highlight is an overlook on which you can see to Boston, and there's some sort of stone structure. Can someone chime in on how the place is from a riding perspective?
So my big question is… I've seen posts on here about Russell Mill, but never figured out where that is… is it near North Andover?
Also, hey, North Andover folks! Say hello! I'd love to meet a few of you! (If you see someone on a black Cannondale RZ with white decals and a Lefty, it might be me)
Thanks. Let me know if I can answer anything else about riding in the area.