The McKenzie River Trail is one of the absolute best mountain bike trails in North America. Nearly 25 miles in length and slightly downhill (when ridden as a shuttle), the trail’s stats are a bit misleading. Most riders will take at least 4 or 5 hours to complete the ride partly because of the technical upper trail and partly because of the number of amazing photo opportunities to stop and regroup.
The trail is heavily used by hikers especially around the area of Tamolitch Pool (often referred to simply as “Blue Pool”), so in 2020 the the trail was rerouted for bikes to bypass the section which has the most hikers.
The first 10 or so miles are a “black-diamond” technical trail, with lots of “exfoliating” pumice and lava (knee pads and platform pedals are a good idea on the MRT). After that, the trail becomes an intermediate route with lot of flowy twists and turns to the bottom. Riders who want to experience this epic ride but are not comfortable with rock gardens can start the ride at any number of mid-way points — the Trail Bridge Reservoir at Tamolitch Pool trailhead being the most popular.
Another option for those that are not into the rocky terrain is to stay on the West side of Clear Lake. This is all singletrack along Clear Lake Trail is fairly smooth and actually a little more scenic. Old growth forest vs lava landscape.