After turning onto Fourmile Basin, you follow the logging road-turned-singletrack for 1.5 miles. Beyond this point you'll be on the original pre-logging singletrack. At 2.4 miles, riders will arrive at the lake. Beyond this point the trail enters Recommended Wilderness and bikes are not allowed.
The lower parts of both Fourmile Basin and Twin Lakes were converted from logging road to singletrack by the Forest Service earlier this decade.