Among Lander's best midsummer technical downhill mountain bike rides. It can be ridden car to car with a long climb on pavement, or riders may be shuttled up switchbacks from one of the lower parking areas to the start of the trail near the Fossil Hill Parking area. A third option is to ride up the Chain Reaction trail and down the lower Catalyst. This is a one-way downhill trail. Riding up the Catalyst is inviting a nasty head-on collision.
From the Fossil Hill parking lot, descend the two track road SE for only 200 yards to a cattle guard and immediately turn left onto the singletrack. This is the beginning of the Catalyst. Traverse around the SE side of Fossil Hill, climbing through sage and Aspen glades on rocky singletrack until you begin to descend North.
Switch to downhill mode for a screaming fast descent through open alpine meadow where you'll test your shocks and tires. The real fun begins as the trail re-enters the trees at bottom of meadow. The trail winds through spruce and pines for several blissful minutes before reaching an easy to miss right turn which jumps over a small berm. (If you continue left, you descend the Chain Reaction trail, which is stellar but much less rowdy.
Around 1/2 mile below the turn off, you'll come upon some optional 6-10 ft cliff drops off the right side of the trail with decent landings. Stay left to avoid mandatory drops. Another 500 yards of berms and shady singletrack brings you to a sharp right hairpin. Use caution here as there is an exposed 3 ft limestone offcamber rollover just after the hairpin. First timers should scout before riding!
After the drop, a long, narrow and fast traverse brings you to a left turn and down a steep and rocky 200 yd skidline gully in the trees. There are optional boulder drops on the left, midway down the gully. With a left turn, leave the gully and traverse left on narrow rocky trail for several hundred yards before passing between two house-size boulders and T-ing into the much more casual Moose Gulch
At the T, turn left for a shorter, steeper ride (pictured on map) or turn right to add .5 miles and a mellower climb back to the car. Both directions bring you to another jeep road option on the left. Stay right and head down to a small often dry creek with a skinny across. 100 yds after the creek, you'll arrive at the walking bridge. Turn right and cross the bridge to the Warming Hut parking lot to meet your shuttle driver.