The Old Trench Road isn't really a road. It's a relatively steep and rough singletrack that descends from Ridge 157 near Rock Springs. The recommended loop ride is 17 miles, starting at 6500 feet elevation at Tibble Fork and rising to 9400 feet. Total climbing will be about 3100 feet.
Shuttle option: If you have someone drive you to the top of Pole Line Pass, you've got a 9-mile ride with 3000-vertical of downhill. Good luck finding someone who wants to drive this bumpy road while you rock and roll on your bike.
The first mile is relatively pleasant with great views, as the trail traverses the hillside. Then it turns downhill and becomes more technical. The most difficult spots are lower down on Trail 172, where rocks lie in the bottom of a steep trench. Did I mention you need good bike-handling and braking skills?
After reaching the Mill Canyon Trail, the rest of the downhill (at 500 feet per mile) seems absolutely tame.
0.0 Tibble Fork, straight onto gravel road
as pavement turns left uphill
4.7 Keep R uphill at road fork
8.0 Pole Line Pass. Find ST on right.
(If you go immediately uphill: wrong way!)
N 40° 31.901 W 111° 34.243
8.6 Fork R
N 40° 31.404 W 111° 34.249
10.3 Straight (L) at Forest Lake fork
N40 30.347 W111 34.861
Begin tough steep climb
11.0 R downhill onto Trail 181, OR
11.1 Hard R downhill onto Trail 181
N40 30.029 W111 35.182 (Continued...)
12.8 Fork L downhill
N40 29.618 W111 36.705
13.2 Holman in from L (go R downhill)
N40 29.344 W111 36.559
13.6 Fork L onto 172
N40 29.150 W111 36.740
15.0 R downhill at Mill Canyon Trail
N40 28.577 W111 36.699
16.0 Straight (R) downhill
N40 28.655 W111 37.666
17.0 Arrive reservoir, cross creek
N40 29.031 W111 38.378
(Caution! Very difficult climbs!)
Only very strong riders who love pain
should consider this route...
0.0 Tibble Fork, straight onto gravel road,
watch for trail dropping to river,
cross river to Mill Canyon Trail
N40 29.031 W111 38.378
1.0 Fork R on Mud Springs Trail
N40 28.655 W111 37.666
1.7 Left uphill on Tibble Fork Trail
N40 28.158 W111 37.592
3.0 L on Ridge 157 northbound
N40 27.547 W111 36.894
4.6 L on DT
N40 28.061 W111 35.681
5.1 ST just to R across dirt road
N40 28.445 W111 35.277
Begin hard, ugly climb (hike-a-bike)
6.6 East side trail in from R
N40 29.472 W111 34.760
Then pass Rock Springs
6.8 Keep R
N40 29.472 W111 34.938
7.5 L downhill onto Trail 181
N40 30.029 W111 35.182
9.2 Fork L downhill
N40 29.618 W111 36.705
9.6 Holman in from L (go R downhill)
N40 29.344 W111 36.559
10.0 Fork L onto 172
N40 29.150 W111 36.740
11.4 R downhill at Mill Canyon Trail
N40 28.577 W111 36.699
12.4 Straight (R) downhill
N40 28.655 W111 37.666
13.4 Arrive reservoir, cross creek
N40 29.031 W111 38.378
Single-page riding guide
GPS track files and route (right-click and "Save as..."):
Via Pole Line Pass:
Loop up North Fork to Pole Line, South to Old Trench
Via Singletrack from Tibble Fork:
Mill Canyon to Old Trench Lariat Loop
Mill Canyon to Tibble -157- Old Trench Tibble up - 157 - Old Trench
High-res topo (1.2 MB): View
Lodging, camping, shops: Links to north Utah County resources