Cutthroat Pass trail junctions with the Pacific Crest Trail when it tops out on the ridge. It is prohibited to bike on the Pacific Crest Trail and you’ll certainly run into hikers while you’re up there. If you’re feeling generous, bring some snacks to share with them.
As there will be hikers on the trail, please ride with care, in control, and give right-of-way.
A shorter option is to ride out to Cutthroat lake and back, which is a total of 5 km round trip.