Not Just for Snow: Fat Bikes in the Desert

February 16, 2017 - Nicholas Carman celebrates Fat Bike February with Adventure Cycling.

When someone asks me, “Are those big tires hard to pedal?” I usually think to myself, “Well, it’s easier than walking.”

While fat bikes, with their 4.0in. and 5.0in. wide tires, have been synonymous with winter cycling for years, many riders are expanding their use in desert climates around the world, applying that increased flotation to sandy tracks.

And through many months of riding in Baja California this past year to develop the Baja Divide route — a 1,700-mile off-pavement ride down the Baja peninsula in Mexico — we learned a few things about fat biking in the desert. For riding desert routes like the Baja Divide, we’ve settled on mini-fat tires, known as “plus tires,” and specifically, 3.0in. wide tubeless tires, for their mix of nimbleness and flotation. See more on Building a Bike for the Baja Divide by Nicholas Carman.

Tubeless tires are essential

Tubeless wheel technology has been around for over a decade, but tubeless-ready rims and tires have only become common on quality mountain bikes in the past few years, including plus bikes and fat bikes. Tubeless tires are installed without tubes to a tight-fitting rim, and liquid sealant is used to complete the airtight system. Thus, if and when a tire is punctured, the sealant at the site of the puncture reseals the tire. In most cases, you’ll never even know that something penetrated the tire! Tubeless tires resist flats, roll more efficiently than tires with tubes, and create a lighter wheel system. We love tubeless tires for all these reasons, but the ability to continue riding even with dozens of thorns in your tires — well, that’s just short of magic.

No matter your specific tire width, for desert riding, tubeless tires are essential.

Air down for flotation, air up for rocks

One of the main features of large-volume tires is the ability to run low tire pressures, which widens the profile of the tire at the ground and increases flotation on soft surfaces like sand, snow, and deep gravel. When riding the Baja Divide, however, varied terrain is present and soft sand may be interspersed with sections of hardpacked roads with embedded rocks. For fear of denting a rim or damaging a tire, the ultra-low pressures you might use on sand are not recommended for riding rocky, technical sections. You could change tire pressure every time the terrain changes, but a little compromise might keep you riding rather than pumping your tires every few minutes.

Let some air out to make riding soft sand easier, but don’t forget to add air for that rocky descent.

Learn how to fix a tubeless tire

You can expect fewer flats with tubeless tires than with a conventional tube and tire system. However, the kind of catastrophic tire damage that is possible with a standard tire is also possible on tubeless tires. Three major methods of tire repair are possible.

• Plug kits provide tacky rubberized ropes, called plugs, that are inserted into the site of a large puncture or minor cut to plug the hole. 
• A curved needle — essentially a conventional needle bent into an arc — is used to stitch larger cuts in the tire. The curved shape allows the needle to enter and exit the tire in one stroke.
• Tubeless patch kits are available and function like an inner tube patch, but the patches are tougher and larger in size and the best way to use these patches on a tubeless tire is from the inside, requiring removing the tire from the rim. Because reinstalling a tubeless tire in the field can be challenging — a rapid burst of air is usually required to seat the bead — one should make every effort to keep the tire on the rim, unless you’re confident a good pump or CO2 cartridge can reseat the bead.

The best prevention against tire damage in the desert is to select durable tires with tough, reinforced casings such as Specialized Grid, Maxxis EXO, Terrene Tough, Schwalbe SnakeSkin, and WTB TCS Tough.

In short, for desert fat biking on rides like the Baja Divide, invest in heavy-duty tires, use copious sealant, and learn to repair a tire without removing it from the rim.

Nicholas Carman has been traveling by bike with his partner, Lael Wilcox, since 2008. This past season, they researched and developed the Baja Divide route and spent several weeks riding in Alaska in March. More words, images, and ideas at gypsybytrade.wordpress.com and bajadivide.com.

Photos by Nicholas Carman

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