From the Glacier Gorge trailhead follow the directions for Mills Lake. Once past Mills and Jewel Lakes, watch out for trees felled by an avalanche. Head West towards Glacier Creek and locate large flat rocks that make the fording of the creek easy. On the West bank locate the beginning of the trail that climbs toward Shelf Lake. The trail is faint at times, but it is worth looking for because the ascent is very steep and the vegetation very thick. Occasionally one has to scramble, but not much. True bushwhacking up that slope would be dreadful.
The trail is reasonably well marked, but it is not too difficult to lose it. Keep in mind that it only crosses to the South of Shelf Creek at the very end.
The trail terminates near the outlet of Shelf Lake at about 11200 ft. A bit of krummholz navigation is required to reach Solitude Lake at about 11400 ft. From there continue into the valley heading West until a small pond surrounded by very large boulders. This is where the route starts and is about half way between the head of the valley and Solitude Lake.
The route attacks the Northwest face where the Arrowhead "mellows" considerably. Locate a ramp/gully that ascends diagonally towards the lowest point of the ridge. (That means that if you look at the NW face, the ramp/gully goes up and to the right.) Proceed diagonally until you reach a little platform overlooking a steep gully coming up straight from the valley floor. Climb this gully for about ten feet and then resume the diagonal ascent. You are soon on talus, and in due time you reach the ridge. Depending on your angle, you may reach the ridge at its lowest point (where runners mark a rappelling station that one could use to descend on the South side) or further up to the East. Once on the ridge, climb East on talus to a false summit first and the true summit shortly after. From the lowest point of the ridge the summit is about one fourth of a mile away and 200 ft up.
The crux of the route, at least as we executed it, is where it crosses the steep gully. There was snow on the rock when we climbed it, which didn't help in estimating the difficulties under normal conditions. Overall, Roach's rating of Class 4 felt about right. However, the main thing to watch out for is unstable talus. It is not pervasive, but rather common on both slopes and ridge.
Standard hiking equipment. A helmet would add to safety. As with most other ascents in the park, early in the season crampons and ice axe may be necessary.
If you have information about this route that doesn't pertain to any of the other sections, please add it here.
For those of you who have Lisa Foster's excellent guide Rocky Mountain National Park - The Complete Hiking Guide, note the following error on page 55. The map shows the trail to Shelf Lake on the south side of Shelf Creek. The trail is actually on the north side of the creek.
Foster's description on page 54 is correct, as is brenta's here on SP.
Yes, I was at Shelf Lake on Saturday with Aaron and Ellen. The rest of their hiking group bailed out on the Pagoda climb. They must have heard "that Nelson guy" was tagging along.
Shelf was one of the most spectactular places I have ever been in RMNP. It requires many return visits. The weather was not cooperating so we didn't get past the lake itself, but the Arrowhead and Thatchtop now await ascents from there. I also wouldn't mind being there are crack of dawn for photography.