Mount Jasper is a remote and complicated peak in the Indian Peaks Wilderness. It has at least distinct ridges which reach the summit and as many faces between them. The East Ridge route is perhaps the most accessible from a Class-1 hiking trail and travel on the ridge is pleasant and relatively easy. However, getting to the ridge crest is non-trivial requiring an unpleasant talus climb or an early-season snow slope ascent. Combined with some of the other routes, it makes a good circuit tour of Jasper and its many ridges and faces.
Jasper from the East Ridge
From the Fourth of July Trailhead, follow the popular Arapaho Pass Trail one mile to a signed junction for Diamond Lake. Traverse back down to the creek and cross on a good bridge before heading back up 300' to Diamond Lake. From the lake, follow the faint trail on the right hand (NW) shore past campsites and ascend a slope to a broad and scenic tundra bench at 11,400'.
Alternatively, Diamond Lake may be reached from Hessie TH via a hard-to-follow trail from Jasper Lake. This approach is much longer (10 miles) and is not recommended.
From the bench at 11,400', the East Ridge defines the right hand side of the valley. Your task is to get to the top of it by whatever means look best. In the early season, several moderate-angle snowfields provide easy access via a 500' snow climb. Otherwise, scramble up the loose and treacherous talus to the ridge at 12,000'.
Once on the ridge, head west over several humps. The largest is Pt. 12587 where the summit and false-summit of Jasper come into view. Wind comes whipping in over the north east ridge and fills the saddle below the false summit with conciderable snow in the winter. In the spring and early summer, there is a large SW-facing cornice here which should be avoided. The final hundred feet of climb to the false summit is surprisingly steep and exposed. An ice axe may come in handy.
From the false summit, scramble down to a saddle and up to the true summit which is a few feet higher.
East Ridge from below the false summit.
Standard hiking gear. In the early season, an ice axe and crampons may prove useful.