From Gerry Roach's 14ers book [his description in brackets]: [Just after the trail crosses Scott Gomer Creek and starts up Bierstadt's west slopes, leave the trail and hike 0.7 mile east-northeast, staying well south of bogs along Scott Gomer Creek. Cross to Scott Gomer Creek's north side and climb 0.8 mile northeast up the slope north of upper Scott Gomer creek.]
To do Evans by itself (without doing Bierstadt first), you will leave the main trail after the creek crossing, before it cuts back to the right (less than 100 yards after the creek crossing). Make your way through the willows, staying away from the creek proper (to avoid the swamp), at a roughly 50-60 degree heading. There is no trail through this area, so don't expect one. After maybe half a mile, you will make your way back across to the other side of Scott Gomer creek and pick up the trail in the forested area to the northwest (see descent notes below). If you don't find the trail, that is OK. Just keep heading in a generally northeast direction, past a large pond toward the slopes generally following the creek.
[Skirt north of all the cliffs that extend for 1 mile northwest of the Sawtooth and reach the gentle, open slopes on the northwest side of Mount Spalding (13,842 feet).]
Depending on your level of conditioning and acclimitization to alititude, these may not be very gentle slopes. If you're on the trail, it will peter out at the top of a slope. You will be above most of the willows at this point. Make your way east, staying north of the cliffs Roach talks about. Hike up the steeper slope to the ridgeline at the top of the cliffs, at which point the slope eases greatly. The rounded summit straight ahead of you will be Spaulding, and at this point the false summit(s) of Evans will come into view as a rocky block at the top of the ridge.
[Cross to the south side of Spalding's broad west ridge, skirt south of Spalding's summit and reach the west end of Evans' west ridge at 13,900 feet. Scramble east along this ridge for 0.7 mile to Evans' summit (Class 2). Most of this airy, fun traverse is on solid, sculpted rock. The traverse stays above 14,000 feet as it crosses two false summits. The eastern false summit reaches 14,256 feet.]
I walked along the slopes at the top of the cliff band and the "shortcut" gully Roach describes in his book on gentle slopes, south of Spaulding's summit. If you like wildlife, I saw a fairly large heard of mountain goats in this area grazing while I walked on by. By this point at the top of the ridge you will most likely run into climbers who are either doing the Bierstadt-Evans double, hiking from Summit Lake, or performing a recon from the summit after having driven up. The traverse over the false summits is probably best taken on their south side (stay below the top of the ridge to the right). There is somewhat of a path through there, with cairns marking some of the route. As you get around these false summits, you will see the top of the Mt Evans highway and the summit buildings.
I started from the trailhead with three other hikers who wanted to do Evans. Since they hadn't been there before, I led them through the willows all the way to the gentle slopes south of Spaulding and north of the cliff band. By this point, I darted toward the summit and never saw them again. Don't know if it was conditioning or determination to summit, but I went to the top and didn't see them on the descent. I assume they turned around disappointed, as their car was gone by the time I got back to the trailhead.
Descent notes: since I ran into a thunderstorm with lightning strikes about half a mile away on the descent, I decided to leave Spaulding for another day, and just descend the way I came in. I was considering trying the "shortcut" Roach talks about in his book, but perhaps another time. The descent follows the same slopes as the ascent, down the first easy, then steeper slopes back toward Scott Gomer creek. Find the most friendly creek crossing (there are several), then you can pick up the trail again. As a point of reference, look for the large pond you passed earlier ahead on your left, to the right of a forested area as you descend the steeper slopes. The trail goes past this pond into the forest, and will lead you back into the willows not far from the trailhead. That's the good news. The bad news is that the trail is mucky and soupy much of the way through the willows, and fades into oblivion before you get back to the trailhead. Kind of makes you wish the Colorad!
o Fourteeners Initiative would build boardwalks over these willows as was done for Bierstadt. You will find yourself thrashing about trying to get back to your car, and if you get stuck in a storm like I did, you can get soaked from head to toe before you're finished. (Hint: bring a change of clothes and leave them in your car.) As I was preparing to leave the trailhead, I heard several others who had descended the same way that day complaining about having to trudge through a swamp to get back to the car. I guess it's a rite of passage, though the experience makes it the worst 14er I've done so far (I'm up to 8 now). It would be possible to go through this mess at the start of the hike and take the trail up as far as it goes, but you would first have to find the trail somewhere in the willows, and this is easier said than done.
Steve Bonowski adds:
Good report, Jim. There is an easier route from Guanella Pass. There is a trail (hard to find) that leaves from around the lower, north parking lot and winds its way n.e. towards the slope at the north end of the basin. It is wet in places, but doesn't seem to have the bogs & willows of the route described in Roach. This trail dies out at treeline and then one does a tundra walk east to either gain the high ridge described by Jim, or to contour on the slabs on the south side of the Evans summit ridge. The lower route is mostly Class 1+ with some Class 2 mixed in. I don't recall much in way of serious scrambling in the two times I've done this lower route.
On the return, there are/were a couple cairns at treeline to help you in finding the trail back down to the parking area. Should note that this trail is not all on the USGS topo. If it's not an FS system trail, it may be prone to obliteration if & when the FS gets around to it.