Tour de France

Tour Tech: DeFeet’s UnDXstream Tuff-n-Lite shirt

DeFeet isn't just about the feet. The company's made light, strong base layers for years, and its latest is a marvel.

What do socks and base-layer shirts have in common? They’re both underwear. While cyclists, especially in warm weather, may not always wear an undershirt, they almost always have socks on under their shoes. So it makes sense that people who know how to make socks that keep a cyclist’s feet comfortable in all kinds of weather would also understand how to make base layers to keep a cyclist’s body comfortable as well.

2010 Tour, stage 17, UnDXStream base layer
The UnDXstream base layer is super lightweight, super tough and abrasion-resistant to boot. It will be available to the rest of us in 2011.

That’s why it should not come as a surprise that a sock company — one whose very name only focuses attention below the ankles — would have the most extensive line of cycling base layers in the world. And that line just became more extensive with the addition of the toughest, coolest undershirt in the world, one that Mark Cavendish, Michael Rogers and the rest of the Columbia-HTC team depend upon for protection from the heat as well as from the road.

DeFeet’s Shane Cooper launched the modern cycling-sock business when he came up with his Air-E-Ator CoolMax socks. For the first time, riders could get socks that lasted and lasted while being comfortable, super breathable, non-bunching and capable of being decorated with any graphics one desired.

DeFeet socks have been so widely copied that the once-wide gulf in quality and features between a DeFeet cycling sock and the competition has narrowed dramatically. And when Cooper’s factory was wiped out in a fire seven years ago, stopping delivery of its socks for a year to a market it had largely created, others filled the void.

The company has finally become profitable again, but during all the years spent getting back on its feet — which included not spending any money on marketing — DeFeet lost its head start over its imitators and ceded a tremendous amount of market share to them.

But socks have never been the whole story for DeFeet. The company has always been committed to producing everything it makes in the United States (North Carolina) and reducing the environmental impact of those products. DeFeet makes its CoolMax socks from recycled pop bottles and places them in recyclable, minimal-impact packaging. Plus the socks can be worn for years before they develop holes, reducing need for replacement.

And then there’s the DeFeet base-layer story.

Pro riders have depended on DeFeet base layers for many years, even when their sponsorships didn’t permit display of the logo. I’m sure you’ve seen top riders in the Tour de France wearing undershirts with holes cut out right over their breastbones. Now you know why — they wanted to wear DeFeet shirts but had to lose the logo to keep their sponsors happy.

Cooper brought fabrics from the shoe business into base layers. The UnDLite shirt is made of the super-lightweight DriLex fabric found in athletic shoe liners. It’s incredibly light, thin, stretchy, breathable, moisture-wicking and form-fitting. I keep an UnDLite sleeveless shirt in its reusable plastic bag and carry it along on mountain rides; it’s so light and packs so small that there’s almost always room for it, and it makes the difference between being able to control the bike and shaking uncontrollably with cold when descending from a 12,000-foot pass with soaking-wet bib shorts and jersey.

The UnDShurt, made with MicroSupreme acrylic nanofibers, feels as soft as silk, draws moisture away from the skin (thanks to the polarity of the acrylic) and moves it to the surface to evaporate quickly. It is light, yet thick enough to be warm, and it’s found in almost every pro’s closet, whether it’s sleeveless or short- or long-sleeved.

DeFeet UnDWool shirts, made of New Zealand wool, are a more recent addition. They serve as well and look as good for everyday use as they do as cycling base layers. The soft, washable wool is comfortable against the skin without being scratchy and provides warmth across a wide spectrum of temperatures, weather conditions and exertion levels.

But DeFeet’s particularly unique new offering is the UnDXstream shirt made of Tuff-n-Lite fabric — it’s the toughest shirt around, yet amazingly light and super cool in hot weather.

The Tuff-n-Lite fabric is woven out of ultra high molecular weight polyethylene (UHMWC), also known as P-Tex, the same material used in sintered ski and snowboard bases.

You can ski hard for years and years on super-abrasive snow and you won’t wear down your ski bases. Even when you hit rocks at high speed, the amount of damage the base sustains is always surprisingly small.

But because UHMWC is so resistant to cuts and scrapes, it is extremely challenging to make into yarn and knit into fabric. However, the company that makes Tuff-n-Lite is near to DeFeet and has the ability to knit fabrics out of super-tough items like stainless steel wire.

Tuff-n-Lite is made into sweaters, gloves and arm protectors for workers in the glass industry. It’s also made into hockey socks and ice-skating tights, to prevent potentially life-threatening cuts from razor-sharp skate blades, and used for motorcycle glove liners for its coolness and its toughness.

It’s hard to imagine that a fabric used for making cut-resistant lightweight work gloves would also be about the coolest fabric you’ve ever felt, but it’s true. Close your fist in a Tuff-n-Lite glove, and the minute you open it again, the palm and finger areas warmed by closing the fist immediately feel cool, even cold.

This is why Rogers likes his UnDXstream shirt so much. The skin feels far cooler with it than without anything at all, and the shirt is super lightweight, super tough and abrasion-resistant to boot. No rider likes to think about falling down, but a shirt that not only is lighter and cooler than any other choice yet still protects the body from road rash is a no-brainer.

Had Cavendish been wearing it when he stuffed his front wheel under Heinrich Haussler’s in stage 4 of the Tour de Suisse in mid-June, bringing down both of them in a pile with some other top sprinters, his back might have not been so torn up. On the other hand, if he’d come up unscathed, the other riders would have been angrier at him than they already were.

DeFeet may not be unscathed, but the company has gotten up off the deck and back in the game. And it’s time it was recognized for having spent years making underwear for Tour riders’ torsos as well as their feet. The UnDXstream shirt will be available for sale in 2011.
Readers can send brief technical questions directly to Zinn.

Got some mountain bike tech questions? Check out Lennard’s FAQ on

Follow Lennard on Twitter at

Technical writer Lennard Zinn is a frame builder (, a former U.S. national team rider and author of numerous books on bikes and bike maintenance including the pair of successful maintenance guides “Zinn and the Art of Mountain Bike Maintenance” – now available also on DVD, and “Zinn and the Art of Road Bike Maintenance,” as well as “Zinn and the Art of Triathlon Bikes” and “Zinn’s Cycling Primer: Maintenance Tips and Skill Building for Cyclists.”Zinn’s regular column is devoted to addressing readers’ technical questions about bikes, their care and feeding and how we as riders can use them as comfortably and efficiently as possible. Zinn’s column appears here each Tuesday.