The Rae Lakes Loops is one of the most popular hikes in the southern Sierra. It is about 41.4 miles, if starting at the more usual Roads End TH in Kings Canyon. A longer (50 mile) option approaches from the east via Kearsarge Pass from the Onion Valley TH.
Marcia Rasmussen adds:
Rae Lakes Loop is a fabulous run! I have done it in both directions, and my thought is that the clockwise loop is easier for running. The uphill grade through Paradise Valley is entirely runnable, and the footing is very good. If you are conditioned for the run and for the altitude, you can run most of the first half continuously. After Glen Pass (clockwise), the downhill is steep and more rugged, but if you take a kamikaze attitude, you can run it pretty fast. So, in my experience, the clockwise direction is very runnable.
the counter-clockwise direction seem more difficult to me. Maybe you hardcore trail runners are more sadistic than I, but I cannot manage to run the approach to Glen Pass from the south. At all. It becomes a Death March. Then, after the Pass, I'm too spent to do much more than jog that beautiful downgrade through Paradise Valley.
That said, either direction is incredibly easy on the eyes. This is truly some of the very best of the Sequoia High Country, if not the entire Sierra Nevada. It pains me a little to think of racing through this loop to set a record, when there is such fine scenery to enjoy. End of summer, pre-snowfall is the ideal time to do Rae Lakes. Mosquito populations are INSANE until the first frosty nights. There are a few groves of aspens, and I like to aim for early autumn when they have turned to gold. You very well may see me out there. Please take time to stop and say hello. ~Marcia
I'll be heading in tomorrow (10/15/19) to do the Rae Lakes Loop from the Eastern Sierra at the Onion Valley Trailhead since it's a shorter drive for me from Tahoe. Looks like 48ish miles and 11k feet from this side. Planning on a 10-11 hour day.
Can track at share.garmin.com/raelakesloop