Use the Crystal Lakes Trailhead
From Hoosier Pass, south of Breckenridge on Colorado 9, go 7.6 miles north to the well-marked Spruce Creek Road. Turn onto the Spruce Creek Road, and follow it for approximately 2 miles to an obvious parking area.
4 wheel drive vehicles with high clearance can proceed much further. Go past the obvious parking area, and come to a Y in the road. Take the right of the Y. Soon you will come to another Y, and again, you should veer right. When you make this right turn, you will be passing through an open forest service gate. Go past the turn for Francie's Cabin, one of the 10th Mountain Association Huts, and continue up the road past treeline. After 2.3 miles, you will arrive at the Lower Crystal Lake. This is as far as you can drive.
There are several pullouts along this 4x4 road if you decide to bail out and walk the rest of the way. The worst section is near the middle where a number of large rocks line the roadway. A standard 4x4 should be fine for the road, but I wouldn't try it without skid plates.
Begin at the end of the 4x4 road to Lower Crystal Lake (see above). From Lower Crystal Lake, skirt the lake on its north side on the obvious trail. Follow this trail as it does a large switchback on the lower slopes of Peak 10 to the north. You can see this entire section from Lower Crystal Lake.
Follow the trail to Upper Crystal Lake. The Crystal Lake trail does a loop around the lake - do not follow this trail until its end. When you arrive at the trail above the lake, begin to directly ascend the slope above you to the saddle between Peak 10 and Crystal Peak. There is no trail in this section. It is an easy off trail hike over pretty solid talus.
From the saddle between Peak 10 and Crystal Peak, ascend the ridge to Crystal directly. This is a fun ridge run over easy Class 2 talus. Follow the ridge to Crystal's summit.
Round Trip Mileage: 4.72 miles
Elevation Gain: 1,859 feet
Most of the upper route to Crystal Peak
Without snow, this is a very straightforward route. Standard hiking and backcountry gear.
In winter or spring, this route follows a classic avalanche slope for most of the route. Avalanche avoidance skills and routefinding would be a must, along with ice tools, crampons, and snowshoes.