Eagle Trail runs east and west more or less between US36 and N. 55th Street. Eagle can be ridden in either direction and an infinite number of rides can use some or all of Eagle to connect Foothills
Trail, Boulder Valley Ranch, and Boulder Reservoir
. The key is to not be fooled into simply riding the dirt road; a lot of Eagle is paralleled by narrow singletrack that definitely ups the fun factor.
Starting out east at Eagle trailhead on N. 55th Street, head west through the gate. The road is flat and fast here, but again don't be shy about hopping on the singletrack that runs along the south side of the road. In 1/2 mile turn left at the intersection and rip down a hill that twists south. Ride past the pond and begin the mile long climb up the road. Again the road is often paralleled by singletrack through here, though it is probably more fun when riding west to east (as it helps avoid the loose gravel that can be a bit scary when moving super fast).
At the top of the climb Eagle Trail leaves the road to the south and heads up a super steep hill to the top of the mesa. Keep cranking and good luck; it is easy to lose traction here and have to hike the last hundred feet of the hill.
On top of the mesa, Eagle Trail runs mostly northwest through some fun, rocky cross-county stuff. There are a couple of gates and eventually you get spit out on rocky doubletrack and then a dirt road. At its western end, Eagle Trail proper is hikers only, so bikers cruise on the dirt road through here. Turn south on Broadway Street (still dirt here) to connect to the Foothills
trailhead and parking lot or turn around and ride back to Boulder Valley Ranch the same way you came.