MTB Thursday - Fatbikes are Funbikes

We’ve posted stories about fatbikes in the past, but it’s different this winter. Different brands and builds of fatbikes have now filled bike shops across the country. Shops that had denied their popularity in the past have jumped on board, giving cyclists more opportunities to kick the 3.7+ inch tires. Stop in any shop this winter and you’ll feel the fatbike buzz.

While I’m certain many of you have seen fatbikes either at your local shop, on the trail, or through social media, there is a percentage of you that are saying to yourself, “fat tires, fat…what?” I’m also certain that 90% of you reading this haven’t actually ridden one, let along gotten one out on the trail, beach, or in the snow. For that reason, let’s step back and learn a little about these monster truck bikes first.

What is a “fatbike” and why are they so damn fun?

The origins of the fatbike are fairly recent. Even the name, “fatbike,” has been a recent development. Check out our story from last year discussing some of the history, Colorado connections, and other basic fatbike information:

While they were originally designed for snow, riders have found that the versatility of the wide tires has carried over to other terrain in all seasons. Areas that were previously unridable, such as sand and rocks, are transformed into fun alternatives. They have become an option for a wide variety of riders – from intense ultra endurance winter racers to bikepacking/touring riders, to commuters and recreational cyclists.

The fatbike frames are built specifically to accommodate tires that are double the width of normal mountain bike tires. This means a different bottom bracket shell width, different rear hub widths, wheel configurations, forks, and rims.

The bottom bracket width is stretched from the normal 68 or 73mm to 100mm wide. This keeps the chain from rubbing the extra wide tire while maintaining the proper chainline.

Normal mountain bike hubs are 100mm wide in the front and 135mm rear. On a fatbike, the widths are stretched out to 135mm in the front and either 135 or 170mm rear (and one manufacturer is now prototyping a 186mm wide rear hub). While we could get into a whole separate discussion on the hub widths, wheelbuilding, and the specifics of fatbike wheels, it’s important to know that the wider hubs allow the use of wider rim configurations, while maintaining tire/frame clearance, and providing adequate wheel strength.

courtesy of

What a difference a year makes.

Fatbikes have taken a large leap to becoming a regular, accepted slice of the cycling population, both from the consumer and dealer perspective. Several factors have driven the demand over the last few years.

First is that they’re just plain fun. After years of focusing on building the lightest, fastest, carbon race mountain bike to ride the same trails over and over, cyclists are open to trying something different. You saw it with singlespeed mountain bikes. Weight is initially a concern with all the extra tire rubber, but people quickly realize that the weight doesn’t take away from the ride.

The choices of bikes, components, and accessories have grown, which allows cyclists some quality, lower priced options.

Bikes and Tires.
Frames are available in aluminum, steel, titanium, and even carbon. A year ago, the list of companies making fatbike frames as a standard offering was only at about 15. That list has doubled and many small, custom builders are making their own versions. Carbon even hit the scene this year with Denver’s 38 Frameworks .

Fatbike riders have quickly pushed to upgrade and make their bikes into performance machines capable of handling any riding style and still hold up to daily riding and manufacturers have met a lot of that demand. Salsa Cycles recently released a performance/race focused stock model called the Beargrease. It’s a 28 pound fatbike, built with a lightweight aluminum frame and fork and equipped with lighter weight components.

The main two tire manufacturers, Minnesota-based Surly Bikes and 45NRTH, have eight and three tire models currently available, respectively. Widths of the currently available models range from the 3.8 inch wide “Larry” to 4.8 inches. 45NRTH even produces a studded, 4 inch wide tire called the “Dillinger.” Two winters ago, Surly offered up only two options and 45NRTH didn’t exist. Chatter among the fatbike community indicates that many more options will be available in the coming years.

Cyclists have always cobbled together their warmest winter clothes to allow them to get outside in the winter. Until last year, most winter gear seemed to be the last thing on manufacturers’ lists. 45NRTH out of Minnesota has stepped up and started to produce winter-specific cycling products. Rather than just offering a regular cycling shoe that’s just a little thicker and warmer, their newest release, the Wolvhammer winter boot, is designed specifically for some of the coldest conditions normal cyclists would ever encounter. 45NRTH also produces winter-specific tires, headgear, pedals, and chains. Expect to see them releasing other softgoods in the future.

Fatbike specific websites such as,, and, offer up everything you’d want to know about fatbikes, including technical information, new products, reviews, and photos.

Last winter there was a decent selection of races. Ultra endurance races such as the Susitna 100 in Alaska and the Arrowhead 100 in Northern Minnesota are established. There were also shorter, local races to choose from, mostly throughout the Upper Midwest. The race scene exploded the 2012-2013 winter. Two large series, the Great Lakes Fat Bike Series and series formed and have 15 races between them ranging in length from 50k down to 10-20 miles. Since the start of the winter, other smaller series and races have formed throughout the rest of the country.

Locally, the Cloud City Wheelers in Leadville have been putting on a winter racing series for several years.

Leadville Winter Bike Series

The Cloud City Wheelers have been putting on a series of winter races in Leadville. To get an idea of what the races are like, we posted a race report in March from the third race of the series, the Mineral Belt Mayhem:

The 2013 series schedule has been posted and it promises to be another fun-filled, toe freezing, and lung-busting year. Racers show up to the races on fatbikes and regular mountain bikes looking for a hard, fun, and low-key atmosphere. Regular mountain bikes are invited to race alongside fatbikes, but if the conditions are soft, they are hard to navigate and walking would be necessary.

The series kicks off on January 19 at Copper Mountain. The Copper en Fuego was a new race last year that was extremely popular. They increased the flair a bit from the usual Leadville races and added features, including fireworks and more. For more details about the race, be sure to check out the race page here:

The second race of the series is the Tennessee Pass Night Jam on February 19. This is another evening race, so bring your lights to Tennessee Pass Nordic Center.  Come out for a great race on superbly groomed cross country ski trails followed by food and Oskar Blues Beer. Also, dress really warm, because race time temps generally dip into the single digits up there. 5pm Register/Check In. Go to the race site for more information

The Mineral Belt Mayhem is on March 2. The race is an 11-mile loop on Leadville’s Mineral Belt Trail at Night!  The start and finish is on Harrison Ave. during Leadville’s Crystal Carnival Weekend. It’s a unique opportunity to race your bike down the main drag of Leadville. You can take the family up to check out the Skijoring prior to the evening race. For more details of the race, go to the site:

On April 13 the series wraps up with the East Side Epic. It’s a day race that takes a route just east of Leadville’s downtown. Get the registration information here:

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Non-Fat fat bike

Hey guys/gals, the budget (and spouse) won't allow me to add a FAT bike to the quiver, but I want to do those snow races this year. If I get some snow tires for my 29er, will I be ok? Or is it pointless to show up unless you have a FATTY. Those races seem like a blast, but don't want to be hiking the whole time if a 29er can't handle the courses. Any feedback appreciated. HAPPY HOLIDAYS


Hey Gangnam,

If you do your gangham dance across the snow, it doesn't matter what you ride. The answer is that it really depends. The Tennessee Pass race is usually fine on a 29er as it's really cold up there at night and they keep the ski trails groomed, so it's pretty hard packed. You'll still be at a disadvantage because you're missing out on some grip and fun, but you'll be good.I have no idea with the Copper race because I think they didn't have much grooming and it was a hike a bike for most people last year. I expect that they'll be a little more prepared than last year. The East Side Epic and Mineral Belt Mayhem are a toss up. Last year the Mineral Belt race was with new snow. It was really soft and there were a range of finishing times - from 1hr to 3hrs. So, my advice is watch the forecast for those two. If there is more than a couple inches a day or two before, rent a fatbike and try it out. Pedal of Littleton ( knows everything fatbike and rents them. Hope that helps!

Yeah, you would be ok at most

Yeah, you would be ok at most of the leadville races on a "regular" mountain bike. I would try to run the biggest volume tires you have though at a fairly low pressure. Copper race last year was a fairly ungroomed course but had some pavement/super fast packed sections. I did that one on a Fatback with 4.7" tires. At the Tennessee Pass night jam I raced the same bike and was beat out on the last climb by a guy on a 29er.... Those trails are very well packed, but would still be scary on the DHs on a traditional MTB. Hope this helps!