The trail from Foresthill to the Rucky Chucky River Crossing is known as Cal St or the Cal Loop.
A 16 mile section of the WSER100 with a lot of descending and some shortish steep climbs.
Part I
Run downhill on Main St and turn left on California street you will take a right then curve left and next cross a road to get on the single track trail. When the single track ends, take a left on the fire road then the next right down a dusty fire road. Shortly the single track veers right. The first part of Cal Loop (about 5 KM) is a little rocky, technical and mostly downhill. After that, the next 4-5 miles is up and down with some rocky sections. At mile 6-7 you will hit a straight down semi-technical rutted out downhill section. This is the famous Elevator Shaft. At around mile 8 you’ll hit an open space in a pine grove (Peachstone/Cal-2). Do not take the hard right up the fire road. Instead take the wide trailhead on the left side. which is a fun 2 mile or so descent with some switch backs.
Part II
At this point you are more than half-way down to Rucky Chucky running down a fun non-technical descent. After about 2 miles the single track ends and you will take a right onto a fire road and start a steep climb. When you get to the first intersection on the climb go right and continue climbing. The climb curves to the left and when you get to the top go left (downhill). After the short steep down hill you will hit Cal 3 (Fords Bar-Fleet Feet Sacramento runs this aid station in WSER100). Take the single track to the right (slight up hill) to continue the route. Do not take the fire-road to the left that goes downhill from the aid station site.
Part III
After leaving Cal 3. You will find yourself on beautiful single-track that takes you down along the river. Did I say there is the potential for some awesome running here? This is one of the sections that Robb Krar put down some ridiculously fast splits (among numerous others). About 2-3 miles from RC you will hit sandy sections and if it's hot you will be tortured by the sound of the river but you never get close enough for a cool down. The last 2 miles have a section of exposed fire road with a couple of kickers. You will need to veer left if the road splits in front of you on the fire road. This last section can feel much longer than your strava entry will record. When you see a concrete picnic table under a tree on your left and a set of stone stairs going down to the river, congratulations, you have just run one of the most iconic sections of the Western States 100 Endurance Run!
Optional Part IV (not optional if your car is up at the drivers flat parking area)
After playing in the river and regrouping you now have a fun 3.5 mile climb out from the river to Forest Hill Road. The first 80-85% is a grinder up a fire road that is completely exposed. Then you take a right get on the single track going up and finish the last section to Forest Hill Road. Your car should be up to the right and across forest hill road.