In temperatures too cool for running shorts (less than about 50 degrees), I wear hiking pants and underwear. Probably more often, however, I wear pants only to protect my legs from brush, sun, and bugs. In these instances, the additional warmth of pants is actually a liability.
Pants and underwear are Items 5 & 6 of the Core 13, a 13-item collection of backpacking clothing that can be mixed-and-matched to create appropriate clothing systems for every set of 3-season conditions.
The intended application will dictate the optimal pant fabric weight, fiber, and treatments. For cooler temperatures and really intense bushwhacking, a heavier woven nylon fabric is preferred. But if the pants are merely for sun, bugs, and mild brush, a lighter polyester — which will have less durability but better moisture management — would be more comfortable. A permethrin treatment is a must for lighter, loosely woven fabrics during peak bug seasons.
Pant fabrics with a small spandex content (5-10 percent) will offer better stretch and fit, but they will be heavier, absorb more water, and dry more slowly. Pants treated with DWR (durable water repellant) will shed some precipitation when new, but the treatment will quickly degrade due to abrasion, dirt, and body oils. In fact, after a few weeks of use there is no difference between pants with or without a DWR treatment.
For underwear, I prefer boxer briefs made of lightweight polyester or nylon with a small spandex component (5-10 percent) for improved fit and stretch. Merino wool boxer briefs are available too, but I prefer the superior moisture management of synthetics for this application. Indeed, this is an area prone to odors, and polyester only makes it worse, but I rarely notice: my underwear is 3 feet from my nose and trapped beneath my pants.
By replacing Item 4: Running Shorts with tight shorts or compression shorts, which could also double as underwear, the Core 13 could be reduced by one. However, I would discourage it since the optimal fabric weights for these items are different:
- The best underwear fabric is too thin and revealing for standalone shorts. Example: Nike Pro Combat 2.0
- The best compression short material is thicker and more modest, which makes it too warm for underwear. Example: R-Gear SpeedPro Compression Short
RailRiders Eco-Mesh Pant. If I had to settle on a single pair today, these would be it. The specs are very attractive: permethrin-treated, lightweight nylon without any spandex, and wide mesh vents for enhanced airflow in warmer and more humid conditions. They are baggy, which makes them sloppy-looking but which further improves air exchange.
RailRiders only sells direct. If you want to visit a local outdoor retail store to try on various pairs, look for pants such as the Marmot Torrey Pant (stretch) and Mountain Hardware Mesa Pant (no stretch).
Sierra Designs DriCanvas Pant. I take these on all trips in warm or hot temperatures when little or no precipitation is expected, e.g. the Desert Southwest, or California or the Rockies during an inactive monsoon. These pants are tough and very breathable, and they fit me well. But if you only want one pair of pants in your collection and you sometimes backpack in wet parts of the world, go with a pure synthetic pant instead.
Suitable underwear is widely available:
- ExOfficio Give-N-Go Boxer Briefs (polyester/spandex) get phenomenal reviews, as do the
- SmartWool Microweight Boxer Briefs (wool/spandex)