Time Tested – SmartWool Microweight Base Layer

smartwool microweight base layer
No, ladies, this is not your humble author. It one of SmartWool's models. Sorry!

With the exception of a bit of time spent in California I’ve been riding in cold weather for as long as I’ve been riding bikes. You want to ride year ’round here in the Midwest you ride in the cold. For me, some of my most memorable rides have been in the winter months on snow covered trails or ice pack along the frozen shore of Lake Michigan and I like to stay warm so I can be out as long as possible. Main problem for me is that I generate a lot of heat and sweat when I ride especially if I have a “waterproof” shell. Most don’t breathe anywhere well enough for me so I am wet. The problem then becomes staying warm while wet and for me nothing does that as well as modern, Merino wool. The foundation of all my riding below about 65 degrees is the SmartWool Microweight Crew.

Fat-bikes haven’t always existed but cold sure has! When we were kids cotton long-johns, jeans, flannel and hooded parkas were what we had. We rode got wet and cold, rode some more and Technical wear? What’s that? The closest thing I remember to technical wear at that time was my buddy’s wool Army jacket. Seemed to work well for him. It would be a while before I rediscovered wool, especially modern Marino wool from New Zealand, the type of wool that all my current gear is made from.

Fast forward to the early ’90’s when I was in the midst of my mountain bike heyday and we rode year ’round doing our best on the frozen, snowy trails of the day and my go-to cold weather gear was made of polypropylene. Tights and base layers worked OK for keeping warm but the polypro of the day sure did build up a powerful odor! One of today’s wool traits is a super ability to resist odor. I often wear my SmartWool multiple days without stinking myself out of the room! Because SmartWool apparel doesn’t retain moisture, odor causing bacteria can’t get a foothold.

SmartWool Basel Layers actually come in 3 weights, the Microweight that I favor, Lightweight and Midweight. I have a Midweight Zip top too but it is really too warm for me for all but the very coldest Wisconsin winter days. I do use it as a standalone shirt sometimes in the late fall season though.

As far as care goes, one of the things that made me shy away from wool in the ’90’s was hand washing. Since I couldn’t afford a dozen tops, and was riding daily, the thought of hand washing all the time was a turn off. Not a problem anymore! Today’s high-performance wool is Machine Washable in Warm Water on the Gentle Cycle and while line or flat drying may give the garment its best appearance, Tumble drying on low is perfectly acceptable. Several of my Smartwool Microweights have been through this cycle weekly for over 2 years and remain as soft and good performing as ever.

In cool weather I often wear the long-sleeved Microweight Crew over a short sleeve base layer for a bit more core warmth.

In colder weather I double up with the Microweight rather than using a single heavier weight shirt. This lets me remove one as I heat up and can add it back when the temperature drops, we stop for a rest or swap it out for a damp shirt mid-ride. Speaking of damp, while Merino wool does a great job of wicking away moisture and dries fast, these shirts perform almost as well wet as dry. Flexibility is the key for me.

When the temp really drops I use various shells over my base layer(s). The shell usually is some version of a windproof/waterproof, fleece-lined variety. I keep chasing the holy grail of waterproof while still being breathable enough for me. Nothing’s perfect yet but both my Golite shell and a couple of different weights of Foxwear (Look for a review on these soon!) that Lou made for me are pretty close. The cool thing is that with the SmartWool base layers and a pretty lightweight shell, I am good down to about 0-degrees and have great mobility. Below that an additional mid-layer takes me below 0.

In addition to my arsenal of SmartWool gear I also own wool from Ibex, Swobo and Terramar. They all perform well too. I especially like Ibex’s softness! The main thing that keeps me in SmartWool most of the time is that it just fits me better than the rest. Your milage may vary but you really can’t go wrong with any of the current crop of wool base layers. Make like a Sheep and go out and ride!

About Greg Smith 1127 Articles
Greg Smith, known to many site visitors as Sven Hammer, founded Fat-bike.com in 2011 and the site quickly became the #1 online community for all things Fat. You can currently find Greg outfitting Everyday Cycles; a Milwaukee, WI retailer of gear for fatbikers, adventure cyclists and urban assault riders.


  1. I have a NeoShell jacket coming from Lou at Foxwear!!
    What a pleasure it is to deal with Lou!!!
    He walked through all the different traits of his material, and was very patient with my ignorance towards them!! LOL


  2. I totally agree with Sven. Even our migration to wool was basicly the same exept for for I’m Scottish, so wool sweaters have always been the go to mid layer.

  3. The main problem I have found with any of the smart wool micro and lightweight layers is that if you have any stubble on your neck it shreds the shit out of the collar. Other than that, awesome shirts, I own a few.

    • Good point, Pete. I don’t have that issue (lack of stubble in the appropriate area). I also noticed that the newest versions have a contrasting neck line on the inside. Wondering if that may help the durability of the collar? My newest is a year old so I’ll have to get a newer version and check it out!

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