REI Co-op Merino 185 Base Layer Bottoms Review

Overview

The Merino 185 Base Layer Bottoms are REI’s entry in the 185 gsm merino long-john category: 100% ultrafine wool, soft enough to sleep in, and priced well below Icebreaker and Smartwool equivalents once REI’s frequent sales kick in. They suit cold-weather campers, shoulder-season backpackers and anyone who wants one pair of leggings to hike and sleep in. The trade-off is durability, which is the subject of most of the complaints in the product’s 173 customer reviews.

Key Specs

Spec	Detail
Weight	210 g
Fabric	100% merino wool
Fabric weight	185 gsm (lightweight category)
Fit	Close-fitting, elastic waist, tagless
Care	Machine washable; cold water, hang dry recommended
Made in	Vietnam
List price	Roughly $80–85; frequently discounted
REI customer rating	4.2 / 5 (173 reviews)

Performance

Comfort and warmth. At 185 gsm, this fabric sits at the thicker end of what the industry calls lightweight merino. One Slickdeals commenter put it as a touch heavier than the polyester base layers most hikers know. That extra mass shows up as warmth. Reviewers describe these as comfortable right out of the bag, including wearers who usually itch in wool. One tester wore them under shorts in mid-50s wind and reported that legs stayed comfortable, with better wind-chill protection than expected. The same reviewer preferred the REI bottoms to Smartwool’s equivalent for comfort.

Sleep system duty. Many owners buy these as camp and sleeping pants rather than hiking layers, and that is where they get the most consistent praise. Merino’s odor resistance is the draw on multiday trips. Pants that have spent four nights in a quilt don’t smell like it.

Fit. Sizing runs true to REI’s chart, and one reviewer found it slightly generous for a base layer. Taller wearers report the legs end a bit short at the shin and calf; REI sells a separate Tall version for that. The elastic at the ankle doesn’t stretch much, and one owner found the cuffs hard to pull over their heels. That reviewer also flagged the cuff as a likely tear point for people with larger feet. A second buyer said the waistband elastic is weak and slides down over time.

Durability. This is the weak point. The most-upvoted critical review on the men’s page, with 43 people marking it helpful, describes a hole near the ankle in under a week of wear. Within three months of twice-weekly wear, the crotch seam area had multiple holes. A PCT hiker reported the pants fell apart in about two months, with failures in the crotch as well as the abrasion-prone knees, and discarded them in Northern California. Women’s-version reviewers describe the same pattern of holes at the crotch and knees, including a pair that tore at the knee while squatting at camp. Thin 185 gsm knit and a close fit put stress on the seams. Hikers who rub their thighs together on long days, or who wear them as a daily hiking layer, should expect a short lifespan.

Care. Merino requires cold water and air drying. One owner reported no shrinkage with that routine, and another noted the fabric stiffened slightly after a wash with regular detergent rather than wool wash.

Pros & Cons

Pros

• Soft ultrafine merino that most wool-sensitive owners tolerate right away
• Warmer and more wind-resistant than typical polyester base layers
• Strong odor resistance for multiday trips
• 210 g is reasonable for a 185 gsm full-length layer
• Often discounted deeply at REI, sometimes to the $30–40 range

Cons

• Recurring reports of holes in the crotch, knees and ankles within weeks to months
• Ankle cuffs are tight and don’t stretch much
• Waistband elastic slips for some wearers
• Short in the leg for tall hikers on regular sizing
• Full list price is steep for the durability reported

Who Should Buy This

Cold-weather campers, winter day hikers and backpackers who want a soft, warm sleep layer or occasional under-shorts leg warmer will get good value, especially at sale prices. Buy them when they’re marked down, and treat them as a camp layer. Thru-hikers and anyone who plans to wear the same pair daily for weeks should look elsewhere, since the PCT report is a direct warning. A blend with nylon, or a heavier-knit option, will tolerate abrasion better.

Verdict

These are comfortable, warm and odor-resistant, and they are a bargain at clearance prices. At full price, the reliability record makes them hard to recommend for hard use. Buy them as sleep and camp pants on sale, and skip them for a long-trail daily layer.