The start of the East Ridge is at the top of Thunder Pass, on the Kings-Kern Divide. The pass can be reached from either the north or the south of the divide.
From the south, leave the trail at the upper reaches of the Kern Canyon at an unnamed lake just below 10,800ft. Follow the creek north then west up the canyon between Table and Thunder Mtns. From the last lake at the end of the canyon, it is a class 2 scramble up to Thunder Pass. The approach from the south is much longer than from the north, and so the rest of this description will discuss the north approach.
From the north, start at the Roads End trailhead and take the Bubbs Creek Trail. At Junction Meadow turn south and climb the trail up East Creek to its end at the outlet of Lake Reflection. The south side of the lake is blocked by cliffs, so cross the creek at the lake's outlet to the west side, and contour around the lake's north and west side. At the lake's inlet on the southwest side, follow the creek to the canyon above.
From here you have two choices, though both are tedious cross-country routes over talus and large boulders. You can follow the creek southwest to the large unnamed lake just east of Longley Pass. Before reaching the lake, head south up the steep walls on your left. Pass over a fairly flat-topped knoll then climb down several hundred feet to the lake just north of Thunder Cirque. Your second choice is to leave the main creek shortly after climbing above Lake Reflection, climbing to the left of a cascading creek that tumbles down from the south side of the canyon. This canyon provides some nice views to the north and some interesting climbing until the top of the cascade is reached. From here, follow the creek through a series of unnamed, barren lakes until you reach the last one just south of Thunder Cirque.
Conditions in Thunder Cirque can vary widely depending on time of year and annual snowfall. Axe and crampons are likely needed early in the season, and may be helpful on hard snow conditions in the middle of summer. There is a large rocky spot in the middle of the cirque that is usually free of snow. A flat stone here provides a convenient (though hard) bivy site that may be a bit cramped for more than one. Above the rocky area, the cirque steepens appreciably. In late August, it was just possible to climb to the pass without axe or crampons by taking advantage of flat areas made by the suncups. Near the top of the cirque, head for the obvious chute to right (west) which leads to Thunder Pass and the start of the route.
From the top of Thunder Pass, climb large talus and rock along the ridge until just below the south summit. The peak is composed of three summits, the north one being the high point. Bypass the south summit on the right (north side), being careful on some exposed class 3 slopes. There are wide cracks with good holds that allow you to traverse to the northeast side of the south summit. From the north side of the south summit, there is an incredibly airy step across to the south side of the middle summit. It is easy, less than two feet across, but the exposure is exhilarating and will make you pause before crossing.
Bypass the middle summit on the right (east) side, and follow some easy ledges to the south side of the north summit. The class 4 summit block is about 10 feet high, and can be climbed by either a fist-sized crack on the south side or an open book / jam crack on the west side. Pick whichever looks easiest to you. A partner could easily provide a boost to anyone uncomfortable soloing this block.
Axe and crampons are recommended for climbing Thunder Cirque in early season. Rock shoes are helpful on the summit block for those uncomfortable climbing class 4 in hiking boots (which includes the author who was darn glad he'd brought them along!)