Richardson Lake is at the edge of Desolation Wilderness and just about as far as bikes can legally go. It is a pretty, lightly-visited alpine lake.
The PCT/TRT also drop into Richardson Lake from Barker Pass to the north, and Echo Summit to the south.
There are some old hunting cabins along the way, so keep your eyes peeled. These can be worth a side trip. Also of note is the Sierra Club Ludlow Hut just past the lake. It's always unlocked and can be a fun destination to explore.