You'll likely be walking at the start of this trail as you finish climbing over the pass between Willow Creek and the Ross Fork on the Willow Creek Trail
. That trail is the best access point leading to the South Fork of Ross Creek Trail.
Once at the pass, you'll have quick drop on some switchback to the Ross Lakes. There are some good fishing in these two lakes. Go by the lakes and drop some more switchbacks as you leave the alpine behind. There will be lots of loose rocks on the trail so keep your speed in check. Once you have left the switchbacks, the trail will mellow out and you'll have a nice cruise down along the creek. It will be fast and flowy so have a blast. This trail is part of a number of larger loops using Willow Creek Trail
or Skeleton Creek
This trail can also be ridden as an out and back from the bottom, where you can access the trail from Boise River Road. You'll have a significant amount of climbing and you basically turn around when the trail gets steep or push your bike to the lakes.