I've ridden this trail countless times in different seasons, but like all trails in Upper Bidwell Park it is the best in the spring. Middle trail is a great mixture of climbing, descending, technical features, and it takes you almost to the end of upper park. The flatland area at the entrace to Upper Park has some very nice flat and smooth singletrack, after Horseshoe Lake it starts to point up and you get into some moderate technical sections, but still do-able for beginners. After passing Bear Hole to the right, the workout really begins and you get into some harder technical sections, a couple slippery climbs, and some nice dips. This trail dumps out onto B-Trail right above the park road.
You can turn around for some good fast downhill, or head up the park road, cross the creek and go up Ten Mile House to hook onto South Rim or Guardian's Trail. Great way to see a variety of trail surfaces in Bidwell and "session" some technical features.