This is a very fun trail, VERY rocky/technical at times both up and downhill.
If you don't like rocks, avoid this trail!
If you enjoy a technical challenge, do it!
These directions are for the route I took and what the Falcon Guide told me to do(not copied straight from the book), riding this trail backwords from this description should be a good ride too.
From the trailhead on 96:
Continue along South St Vrain creek down trail 909, through some very technical/steep climbing, some of it I'm pretty sure you'll have to walk too.
Eventually you'll hit a road that goes straight and to the left,
Don't go left over the river, go straight up the road.
Theres a short uphill on the kinda rocky road.
The road flatens out and you'll see a gate and just BEFORE that gate
a trail going STEEP up to the right. The trail is marked with an arrow, no trail name.
Carry your bike up this trail, not to worry theres not much hiking here. Everything past this is ridable, shouldn't have to walk your bike anymore for the rest of the ride.
At the next trail juntion, which isn't marked with signs,
continue towards the left down a rocky trail.
At the next junction, you'll see a sign for Sourdough trail 835 going right.
Take Sourdough 835. From here there are a few more trail
junctions, just follow the signs to stay on 835.
After a lot of fun rocky sections of both up and downhill, and
some nice views, after a while you'll hit a wide open area with a big trailhead sign with a map and everything. You can follow the dirt road back downhill to where you started, there's only one intersection you veer right on.
OR instead of going down the dirt road, I think you can keep
going straight across the dirt road for another mile to a
dirt road that will also take you back where you started,
double check the map at this point to be sure.
There are various trails along the way and plenty of areas
to explore, and can be linked up with other tails like Souerdough to
the south, so good luck and enjoy. A detailed map of the area or the Falcon Guides mountain biking book would be good to have with you.