You can access this by parking across from Nourse Rd on Green Road, or by parking at Bower's Spring on Flanagan Rd, or off Vaughn Hill Rd near the Rt 110 (northern)end.
Trails are a good mix of rocks and roots. Has some very good descents and some rockgardens. Top of Vaughn Hill is a great place for collecting Zen and you can see Boston on a clear day if you climb the Pine tree.
Summary: Firstly, this trail receives an overall rating of 5 from me due to the following reasons:
There is enough climbing to satisfy even the most experienced riders.
There is enough downhill to satisfy anyone in MA who doesn't have the time to drive over 30 minutes in order to ride some solid, fast, flowy trail.
The actual area is beautiful, quiet, and well preserved.
I rarely encounter other people in this trail system (no idea why, it is fantastic and much better than other trail networks in Bolton, Stow, Harvard, and Lancaster)
It is very easy to access the trail network.
There are maps located on the Bolton Conservation Trust website. (go to google and type in bolton conservation trust)
There is a solid number of different routes that can taken depending on what type of ride you're after.
Also, one thing I feel compelled to mention is that you probably won't enjoy this trail system if you're the type of person who hates climbing or being really sweaty and is really just interested in easy excitement. As I mentioned, I rarely see others, especially bikers, but when I do they're almost always pushing their bikes uphill or slowly rolling along as if they're ready to fall over. If you're like me, and absolutely love mashing your way uphill in order to bomb down, then you will be thoroughly satisfied.
I try to ride here every day since I live 2 mins away from one of the entrances. There are multiple routes that can be taken and trust me I have tried all of them (i've been riding this trail and surround trails for 10 years). If you're an aggressive rider in above average shape this area is very solid. I have a very, very, very capable bike (rocky mountain slayer 70) and I still manage to have LOADS of fun on Vaughn Hill. The climbs are not easy, the downhill sections are very fun, and I rarely see anyone else.
To put into perspective just how challenging some of the downhill sections are, I use strava and I just recently set a new record time for my favorite segment on vaughn hill (43 seconds) The person in 2nd got 63 seconds, and then it really plummets. It seems as though the average time is around 100 seconds.
Recommended Route: For the best bang for your buck, park along Woodside Drive in Bolton (it is a culdesac). Assuming you do indeed park on Woodside, you will see the conservation sign at the trailhead. Immediately once you're on the trail there is a solid 7-25 minute climb (assuming you want to go straight to the peak, which I recommend) depending on how fast you ride uphill. Normally takes me about 8 minutes to get the peak from the entrance and I'm ready to puke by the time i'm there. Once you're at the peak, there are several options. You can turn around and tear back to Woodside (I average around 22mph on this segment) or you can go down the back side of Vaughn hill (which is another sweet downhill). If you do choose to go down the backside, there are plenty of options as to where to go from there.
Other recommended trails in the same area: Lime Kiln
Bower Springs (connected to Vaugn Hill)
Pin Hill in Harvard (Don't go here unless you have full suspension or an AM hardtail, VERY STEEP)
Summary: A good bunch of trails. You can make a pretty decent loop once you get the trails down. Kinda small area, one of Vaughn-Bowers-Harvard Conservation probably takes about an hour. Not worth more than a 15-20 minute drive.
Vaughn Hill: This is the section between Vaughn Hill Rd, Green Road, Sawyer/ West Bare Hill, and 110. At it's center is the hill itself, with some good trails going up it. Toward Vaughn Hill Road is the more recently added trails which are pretty neat. If you head towards Bare Hill you can cross into Bower's Spring. The trails leading into Bower's are good, the central trails around the lake (nashoba xc course baby) are kinda boring on da bike. If you keep going east through Bowers you can go a little into Harvard to make a longer loop. Trails off Warner Rd, too, but rather bushwhacky.
Recommended Route: If you park at Nourse Rd, take that trail past the beaver dam and enjoy the everchanging sideslope trail. Take a right after the beaver pond at the junction, pausing to curse the evil people who decided to build a house on top of South peak to your left. When you get to the 4 corner junction, go straight (N) and then bear right to climb the east peak. Near the top, turn left up the hill to get to the summit. Then descend towards the west (left) and up to North Peak. Keep heading straight (north) and enjoy the descent. When you hit the field, go towards the road and cross it. There is a trail directly across from the northeast corner of the field. Take this trail towards Bowers. You'll hit a field, go left, skip the first trail on the left, take the next one into the woods. Nice fun rocks. When you finally descend towards the stream, turn left and then take the the next right across the stream and over the walk. do the climb, take a left, cross harvard road, ride through the orchard, go straight and descend through trees, take a left at the bottom, ascend and loop left to the orchard corner where you entered. retrace your steps back to the stream and bridge----
Other recommended trails in the same area: and turn rightof heading back the way you came. nice technical flowing descent. Once you make your way through the rock/mud garden into the field, go back the way you came back to Vaughn Hill. Once you get to Bar Hill road, turn right (north) then take the trail on the left side of the road (west). Take the right at the fork. When you see the first perpendicular trail on the right, take it and descend towards Vaughn Hill road. Cross the little stream, head left (or head right for dead-end adventure) cross the dam, head south (right), and climb back up to the main Vaughn trails. Take a right at the sign/ map/ junction and then take the right at the larger rocky trail, back the the 4 trail junction. Head South (right) back to Nourse.