Mile for mile, the SHR is the most demanding 3-season hiking experience I have had. But Buzz and I were physically and mentally prepared for that challenge; we had also adjusted our expectations accordingly beforehand. The challenges of the SHR probably also, mile for mile, make it the most rewarding backcountry experience I have had -- it put our backcountry talent to the test. The list of challenges on the SHR is long: high elevation/thin air, relentless sun, aggressive mosquitoes, snow travel on heavily sun-cupped snowfields, Class 3 scrambles, miles of boulder hopping, steep and/or loose headwalls below passes, long cross-country sections, technical navigation, and heavy food loads.
About half of the SHR is on-trail and about half is off-trail -- Roper says 100 miles of off-trail. The quality of on-trail segments varies: usually the trails are superbly maintained and heavily used, but there are some sections that seem to have been forgotten by both hikers and trail crews. The SHR uses about 30 miles of the John Muir Trail. The nature of off-trail segments varies too: alpine meadows and granite "ramps" are really nice, boulder fields and sun-cupped snowfields not so much; most of the scrambling occurs near the passes.
There are two parts to traveling efficiently off trail. First, you need to know where you are going. Second, you need to determine the fastest way to get you there. Knowing where you are going…Ultimately, a SHR thru-hiker is heading towards either Mono Village or Road's End, but shorter-term goals must be established: a pass, lake, trail crossing, etc. Buzz and I often planned our route for the next few hours when we reached the top of the passes -- "Okay, our next pass is that V-shaped notch in the ridge across the basin. The most direct route from here crosses the snowfield just below us, skirts the right shoreline of Blue Lake, which is that one over there, and then ascends along the south bank of Quiet Creek, the headwaters of which are just below the pass." Finding the fastest way there…Your forward progress can be slowed by climbs, steep descents, technical footing, and non-straight lines. Therefore, try to avoid these things: climb and descend only when you have to, detour around technical-looking sections, and always remember that the shortest distance between two points is a straight line. These are often conflicting goals -- e.g. the shortest route may involve the most climbing/descending and the most technical footing -- so you need to react to each landscape differently. With practice you will increasingly chose the most efficient routes.
Roper routed the SHR over countless passes, which was not done on purpose but which was a result of keeping the route in sub-alpine and alpine terrain. Some of these passes are easy -- Muir Pass, for example, is climbed via the John Muir Trail. But others are more technical -- Stanton Pass, for example, involves about 200 vertical feet of Class 3 scrambling on each side; and Frozen Lake Pass features a steep north side that is coated in ball bearing-like pebbles. Unless you get off route, there is no technical rock climbing on the SHR, i.e. Class 4 or 5. Class 3 terrain requires both feet and probably both hands, but the likelihood of and consequences from falling are minimal. If you have rock climbing experience you will probably feel more natural during these scrambles. If scrambling is a foreign activity, you will undoubtedly be more natural by the end than when you began. Buzz and I both had rock climbing experience, but Buzz was definitely the stronger scrambler between us, and I therefore had to avoid the temptation to match Buzz' pace and instead keep within my own comfort zone. It's better to go slow than to hurt yourself, because then you are going reallyslow.
Granite slabs. A notable portion of the cross-country sections are across granite slabs, which sometimes makes it seem like you are on a sidewalk. Of course, it's usually not that easy, but the slabs do offer consistent grades and good traction.
Boulder fields. There are seemingly endless miles of boulder fields on the SHR. They usually begin below the headwalls of the passes -- after all, these boulders at one point were the headwall, but eroded off chunk by chunk -- and end somewhere further down, where grass and soil finally take over. Some of the boulders are as big as F350's while others are beach-ball sized. Thankfully the boulders in the High Sierra are usually very stable -- it's rare that they move when you put pressure on them -- and those that are can usually be easily identified and avoided.
Scree fields. Several scree fields must be crossed, climbed, or descended, but they are rare. Granite is a very erosion-resistant rock and it does not break down into scree like other rock types, e.g. limestone or basalt.
Snowfields. The amount of snow that must be crossed depends primarily on the preceding winter's snowfall and time of year. Regardless of these exact factors, I think it's probably inevitable that a SHR hiker will walk on snow at some point during their trip, especially since some of the snowfields are permanent, i.e. they melt but never fully disappear during the summer months, and then they are given new life again during the winter. Alpine snowfields in the Sierra get heavily pocketed with "sun cups" as the season progresses, and this slows travel greatly. The cups start as small depressions but then enlarge as solar rays bounce around inside the depression, hollowing it out; and the melted snow drips into the bottom, making it deeper.
Because the SHR stays near the headwaters of the Sierra's many rivers, it avoids the difficult river fords that are characteristic of the John Muir Trail. There is just one notable ford, at the outlet of the southern Twin Lakes, but it is easy: the water was high-thigh deep but very sluggish in early-July 2008.
There are black bears in the High Sierra and the likelihood of seeing one is fairly high, especially when the SHR dips below treeline. Black bears are not interested in you, but they are interested in your food. Partly thanks to irresponsible backcountry users, bears have learned that humans equal food (and good food at that -- Snickers, peanut butter, salami, etc.) and for many years they regularly outsmarted the humans who tried to protect their food by hanging it, burying it, and even sleeping next to it. I recommend that you protect your food with a bear canister because otherwise you can be fined if you are caught without one. If a bear approaches your camp or you encounter one on the trail, you can usually chase it away by making noise and throwing objects at it. Black bears are far less aggressive than their northern cousins, the grizzly.
Because the SHR is a more challenging hike than a conventional route, mileage goals need to be adjusted. Depending on your skills, experience, and physical fitness, you should plan to hike about 50 to 70 percent of your normal mileage. For context, I normally hike 35-40 miles per day in good conditions; it takes me about 15 hours. Buzz and I comfortably averaged about 23 miles per day on the SHR, hiking about 14 hours a day. If I had been on my own and exerted my usual effort, I would probably average 27 or 28 miles per day, which is about 70 percent. I'm on the high end of the 50-70 range because the SHR's challenges do not affect me as much as they will affect a person with less experience and a lower skill level, e.g. I'm less likely to make navigation mistakes, I'm more comfortable on technical terrain, I can power up steep climbs, etc.
I would recommend hiking the SHR solo if: (1) you are comfortable hiking solo in general, and (2) the SHR is within your skills and experience level. But I thought having a hiking partner on the SHR had some particular advantages. First, it's safer, since Buzz was there to help if something happened to me. This is especially important on the SHR because it's unlikely that another wandering hiker will find you. (We only saw one group of two hikers while off-trail, and we did see human tracks elsewhere now and then.) And, second, two heads were better than one when it came to navigating -- we picked great lines the entire trip and wasted no time climbing to incorrect passes or meandering excessively. If you do go solo, I recommend carrying a SPOT Satellite Messenger on this trip because the odds of something happening are considerable.