Best Wool Base Layers - Icebreaker, Ibex, DuoFold & Louis Garneau

I give myself the right to be particularly picky about products as close and intimate as base layer clothing. Long johns, skivvies, union suits, long underwear — whatever you want to call them — must be well-fitting and comfortable. For outdoor athletes, they must also strike a perfect balance of breathability and insulation.

For two months, I’ve tested a dozen base layer models running, biking, climbing and skiing like a madman in temps ranging from negative-20 to 45 degrees. Here are my results:

Quebec-based Louis Garneau (www.louisgarneau.com) produced my favorite all-around base layer top in the test. The company’s Zip Turtleneck ($50) employs a light, fleecy fabric on front and a thin polyester on the sleeves and back. This simple design keeps your front core area warm while letting your often hot-and-sweaty back breathe. A 9-inch zip on front opens the chest up for ventilation when needed.

While pricey, the Mondo Zip ($70) and Strider legging ($75) from the New Zealand company Icebreaker (www.icebreaker.com) are quite nice. Both pieces are made of 100 percent merino wool. They breathe wonderfully and are good fitting and comfortable. The wool does not itch a bit, and in fact is so finely spun the fabric could be mistaken for polypropylene. Icebreaker promotes wool as a biodegradable, annually-renewable resource, and the company buys its wool from small local farms in New Zealand.

In the budget category, Duofold’s (www.duofold.com) Varitherm top and bottom go for around $35 and $40 apiece and provide admirable performance. The top is a little thick for aerobic activities in weather above 10 degrees, and the bottoms did not fit me as precise as I like in the waist. But overall the polyester-based layers are a good deal for athletes who don’t feel right putting down a C-note for a long johns set.

Mountain Hardware’s (www.mountainhardwear.com) line of Hyperdry base layers can also be put in the bargain bin. The Zip T ($30) and Tights ($25) are made of a thin, 100-percent polyester stock that provides enough insulation for highly-aerobic wintertime activities. Their breathability is only average, however.

Finally, in the why-not category, wetsuit maker American Wave (www.americanwave.com) has jumped in with a winter line of base layers. A derivative of the company’s rash guard and wetsuit designs, the Compression Snowsuit is a one-piece, ivory-white suit with a full-length zipper. The polypropylene fabric is thick and warm, but not tremendously breathable, making the suit appropriate for sports like downhill skiing and ice fishing but not running or mountaineering. An added bonus: American Wave touts the suit’s tight-fit design as advantageous for muscle compression, which can increase endurance and lessen the chance of injury.