This approach to Big Basin is a bit more of a walk than the East Fork road, but will lead you through some breathtaking Pioneer scenery
The approach to this route is the Hyndman peak trailhead. To get here take the East Fork road north of Hailey. Follow this road until above the mining town of Triumph, where the pavement ends. Turn left at the first major fork you reach. The road winds several miles until you reach a gate at the Hyndman trailhead. Park here.
Follow the trail as it climbs gently toward the base of Cobb peak. As you near the peak, start looking for an indistinct split in the trail, which will lead you right of Cobb. Keep a sharp eye, as this trail is quite faint. Once on the correct trail you will ford the creek, which can be swift and deep until late in the season. (In late July, the water still came to mid-thigh). Once across the creek, follow what will become an obvious road. This is an old mining road which is no longer in use. The road makes its way into the mouth of Big Basin.
From here just follow the trail until it disappears. You'll see Big Basin peak appear at the head of the basin. There are several cliff bands to navigate as you make your way up the basin, and it's best to tend toward the left as you climb. There are several obvious gullies which you can utilize.
This is Big Basin peak from big Basin. Aim for the ridge to the left of the peak for easy ascent.
Once you have a view of the ridge at the head of Big Basin, find an ascent gully (to the left of the peak) and pick your way to the ridge. Most of the rock in this area is solid, so route finding is not difficult. Once on the ridge, follow the easy slope to the peak.
Big Basin peak from the ridge connecting it to Old Hyndman
Note: If desired the traverse to Old Hyndman is not difficult.
This is primarily a summer climb. The basin melts out early, so snow/ice should not be an issue. Early the season you may encounter some snow on the northeast ridge.
Keep a sharp eye out. You will be rewarded with views of elk in the basin and mountain goats in the rock. I have seen moose on several occasions while in the Pioneers.