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Princess Di Trail
Reached by paved Three Mile Canyon Trail,
with return via Rail Trail

The Princess Di trail is a singletrack trail that hugs the hillside east of Promontory. The track is narrow, with some areas of loose volcanic rock that create tricky traction on the many tight switchback turns. This makes the trail "expert" in technical requirement, although intermediates can ride it by dismounting on most of the turns.

View northbound a few miles into the ride. You'll spot a few huge homes on the hills above the trail. Photos by Bruce, August 16, 2010.

Princess Di can be reached directly from the bottom (northern) end by taking the Promontory/Tollgate Canyon I-80 exit. But most riders do the ride as a loop starting with the paved Three Mile Canyon trail, then finishing with 4 miles on the Rail Trail. For this review, we'll assume you're doing the counterclockwise loop starting from the Rail Trail Promontory trailhead off US-40.

Just getting started. The Three Mile Canyon paved trail has a gentle slope, climbing 400 vertical feet in 2.4 miles, then descending 100 feet over 0.6 miles before you hit the singletrack Princess Di trail.

Princess Di itself is 7.5 miles in length, with the total loop ride being 14.5 miles. The 7 miles you'll spend on the paved Three Mile Canyon and cindered Rail Trail are pretty easy. Still, the ride is a moderately strenuous trip due to the climbing on Princess Di.

Trailhead parking is at 6500 feet elevation. Top altitude is 7300 at the ridgeline 10 miles into the ride, bottom 6300 at the Rail Trail. You'll gain, lose, and regain altitude for about 1800 total feet of climbing.

From the Three Mile Canyon Trail, there are views west to Parley's Summit and south to Deer Valley. After cresting the hill, you'll be above a little golf course stuffed into the little canyon.

Start at the Promontory Trailhead for the Rail Trail (see below). Head out of the parking lot to the street, cross the road, and turn left on the paved path. Keep on the paved bike path, ignoring the many side trails and confusing signs. Climb the hill for 2.4 miles. The paved trail follows the road for the first mile, then veers out into the brush of the hillside, but returns to the road at the top.

Heading downhill after crossing the ridge. The Princess Di trail is just a couple of wiggles away.

At the crest of the hill, the paved path will turn away from the roadway and begin descending. You'll drop 100 feet of the 400 you gained since the trailhead. At exactly mile 3.0, the trail makes a hairpin turn to the right (as of 2010, the pavement ended here). The Princess Di trail forks north (left) at the apex of this turn.

Entry into Princess Di. The trail is very well marked with carsonite signposts. If you find yourself confused, look around for a post, or check the dirt for tire tracks.

Princess Di contours around the east side of the Promontory mountain, keeping just below the easternmost homes of the development. The trail will go in and out of several drainages, gently gaining and losing altitude. You'll hit quite a few very tight and loose switchbacks on this side of the mountain. But if you hate switchbacks, you haven't seen anything yet. Just wait.

The trail skirts an outcrop of volcanic rock, a mix of pumice and ash.

On south slopes, the trail base is fairly smooth overall, but with scattered loose sharp volcanic chunks. These make climbing around a sharp uphill switchback more interesting. Southern slopes are usually bitterbrush and sage with occasional stands of gambel oak.

View east toward Rockport Reservoir.

On north-facing slopes, the trail is hardpack dirt, with a few petrified ruts left over from early season. There are occasional sections of teeth-rattling horse-hoof postholes. The north slopes have thicker brush and oak, with groves of aspen, choke cherry, and maple. 

The last long climb on the singletrack gains 400 feet over about 1.5 miles, putting you on top of the ridge at 7300 feet. To the west are views over Park City and Jeremy Ranch. To the east, Rockport Reservoir sits in front of the Uintah Mountain foothills.

Typical trail section on a north-facing slope. Thick low shrubs such as potentilla mix with sage between small stands of aspen, maple, or oak. There's occasional elderberry, serviceberry, or chokecherry.

At the top, head for the end of the roadway in front of you. Look for the trail post on the other side of the road, about 100 feet before the end. Hit the singletrack and begin your descent. You'll be dropping 1000 vertical feet over 4 miles and countless switchbacks. Fun stuff. Great ride if you've got the handling skills to roll the turns quickly.

View west from the top. The light stripe at mid-left is the end of the subdivision road. The continuing singletrack is across on the other side.

The trail grade on the downhill is usually fairly mellow and consistent. But the track is narrow enough that you'll have little temptation to "fly" and your descent will be interrupted regularly by very tight tricky turns.

Near the bottom, there's a long straight downhill as you and the Promontory Road follow a small creek down toward I-80.

One of the few groves of larger trees, as the trail becomes cool and shady under the maples.

The final bit of singletrack is a steep section that clings to a cliff-like washed-out sidehill. Just ride. It's easier to roll down on the bike than to walk it. The trail ends where Promontory Road hits the freeway exit.

Turn right and cross I-80. Notice the little tree-lined pit to your right. Hike down into the creek (dry in August), turn right, and go through the tunnel under the southbound lane. In between freeway lanes, you'll find the Rail Trail. Turn right and ride uphill 4 miles back to the trailhead.

I-80, with the Rail Trail between the lanes.

Princess Di Trail, counterclockwise loop:
0.0   Back to road N40 43.475 W111 28.309
        Cross road, L on paved trail
        Begin Three Mile Canyon paved trail
0.3   Keep straight on paved trail at all crossings
        N40 43.449 W111 28.082
        (R = to South Canyon Trail)
2.4   Top of ridge, begin to descend
3.0   L on singletrack (end of pavement 2010)
        N40 44.537 W111 26.103
        Begin Princess Di singletrack
7.2   Top of ridge, angle L across
road to ST
        N40 46.140 W111 26.772

Clattering through the tunnel under the freeway, with a bridge on the Rail Trail waiting on the other side.

7.6   Cross paved road
9.4   Drop R on ST as you hit clearing with bldg
        N40 46.684 W111 27.391
10.5 Plunge down to road, turn R and go over I-80
        N40 46.512 W111 28.066
        Immediately after freeway, drop R into "hole"
        N40 46.530 W111 28.161
        R into drain tunnel, go under southbound land
        R on Rail Trail in between lanes of freeway
14.5 L into parking area

On the Rail Trail southbound, between the lanes of I-80. Not as obnoxiously noisy as you'd think. 

Getting there:  Take I-80 eastbound out of Salt Lake City and cross Parley's Summit. Pass the Park City exit, then a couple of miles later, take US-40 south at Silver Creek Junction. In 1 miles, exit at Silver Summit. Turn L (east). Follow the road as it veers north. At 0.8 miles after leaving US-40, turn right on Promontory Ranch Road. Continue about 1/2 mile. Just after crossing the Rail Trail, turn left into a paved parking area with a "Promontory" sign. Begin the ride by heading for the paved trail across the road from parking.

Bathroom: Outhouse at trailhead.
Water: None at trailhead. Convenience store 1/2 mile away.
Camping: None in immediate area. Nearby at Rockport, Echo, or Jordanelle Reservoirs.
Bike Services: Multiple shops with rentals and repairs in Park City.

Riding resources for this trail:
Single-page riding guide:  View to print
GPS track files (right-click and "Save as..."):
    GPX course for loop      GPX area trails
Large-format area topo map (900K): View
Lodging, camping, shops:
     Links to area resources

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