Fat bikes, or ‘Fat Tire Bikes’ are working their way onto the radar screens for many serious riders. They started out life, so the story goes, in Alaska - a ‘DIY’ project resulting from a desire to ride in the snow. Obviously there are those who choose to commute by bike, for whatever reasons, and there are those for whom biking is an important recreational activity. But what happens to your ability to ride when the snow falls?
A couple decades ago a few creative folks set about trying to resolve the issue of being able to ride a conventional bike in the snow. The main issue back then was finding a tire that would offer sufficient ‘floatation’ on soft snow, or on sand and mud. Even the widest mountain bike tires would sink deep into softer snow making riding very difficult. The initial approach to the problem was to widen the forks and change the frame geometry to allow two wheels to be fitted side by side. Obviously this wasn’t ideal but it was the only practical way to deal with the lack of an available wide profile tire.
Some years later, niche bike builder ‘Surly’ became involved and built up a dedicated fat-tire frame. They invested in the tire technology and out came the first ‘fat tire’ bike. The Surly Pugsley became the first commercial fat bike to sell in numbers. The bike is still built to this day having undergone only a handful of small refinements.
As the fat bike market has evolved, pretty much all of the big players have come along with some type of offering. Surly have retained an important lead role in the ongoing development of fat frame geometry, fat wheels and fat tires. In fact, Surly supply the bulk of wheels and tires to other key players in the industry.
It’s now possible to select from tires in the range of 3.8″ up to 5″, in both 26″ and 29″ diameters, and there’s already talk of even wider tires becoming available. This will likely continue to evolve as the market expands and finds its natural boundaries and borders.
Tires on a Fat Bike are what provide the unique ability to move across terrain that would otherwise be difficult to traverse with a traditional tire. Snow, ice, slush, sand, mud even conventional dirt surfaces, and of course tarmac, are all fair game for a fat-tire equipped bicycle.
One of the more popular brands/types of tire on the market is the Surly Nate, shown in the image to the left. The Nate is a 3.8″ wide tire designed to fit a rim from 50mm to 100mm in width.
The key to tractability is running the tire at the correct pressure for the riding surface. Fat tires can be run down as low as 6 or 7 psi and upwards of 25psi. At the lower pressure the contact area flattens out to increase the surface contact area and provide more traction and more floatation. In this context, the word ‘floatation’ is used to indicate that the tire/bike rides on top of whatever surface it is traversing, rather than cutting down into it. So if you think about riding a traditional mountain bike tire through soft snow, you’re going to cut into the snow and sink down to a level/depth where the snow is firmer. This could render the bike difficult or impossible to pedal. With the floatation offered by a fat tire, you’re going to remain mostly on top of the snow surface hence more able to maintain forward motion.
How do these bikes ride?
I’ve only ridden the Trek Farley and it was only a brief road ride. I intent to rectify this soon by investing in my own fat bike for the coming winter season. But you can tell a lot about a bike with a short ride and my impressions of the Trek Farley were extremely positive. The riding position feels like an aggressive single-tracker mountain bike design. It has a short wheelbase, short top tube and wide bars. So the stance is upright and the bike feels nimble. It also accelerates very well. I was expecting to need a lot of force to overcome the static inertia and set the thing in motion, but that wasn’t the case.
I understand that Trek have approached the Farley design by pitching it more towards speed and agility than some of the other builders. It feels like a good approach.
Fat bikes share much of their equipment with conventional mountain bikes. They generally have disc brakes, some mechanical some hydraulic, depending on price. They use standard MTB running gear, many with SRAM group sets, others with Shimano. Levers are usually thumb operated easy shift, designed for use with heavier winter gloves.
Wheels/rims are obviously custom, designed to take the wider tires. Many of the more expensive wheel/rims are drilled-out to reduce weight. BB’s are generally sealed cartridge designs to help keep mud and dirt out of the bearing assembly.
Bars, seats etc are common to MTB’s.
Surly and some of the other builders recognize that the more serious outdoor adventurer types may want to tour via bicycle during the winter months, so they equip certain models in their range with eyelets for fenders and pannier racks, in some cases with front fork mounts too.
Fat bikes are inherently heavier than MTB’s primarily due to the weight of the wheel and tire combo. Many tip the scales well north of 30lbs, with some of the less expensive brands such as Mongoose, pushing towards 50lbs. Already there are full carbon frames with high-end lightweight running gear to reduce the weight and some of the newer carbon bikes are now coming in well under 30#. As tires and tubes evolve the weights are bound to come down even more.
The approach to geometry is all over the map. Fat Bikes came into the market pitched primarily at the ‘fun’ and casual / recreational rider who wanted to extend the riding season and have some fun in the snow, or perhaps on the beach. But what’s happening is that people are finding these Fat tire bikes to be quite competent year-round off-roaders. Most do not have suspension (though this is starting to change) and rely on the compliance of the wide/tall tires to soak up the bumps. And soak up the bumps is what they do well. They roll and bounce over the most difficult terrain, not just snow and clumped ice but also rocks, tree roots and stumps and pretty much whatever else you throw at them. So design approaches are starting to evolve to give them more of an edge as year-round trail bikes.
Terrain and riding conditions
As said already a Fat Bike will handle snow, sand, mud and rocky/rough technical trails with ease. Owners who ride in snow however report varied results. When the snow is packed and compressed they’ll bounce over it with ease, but so will a conventional mountain bike equipped with studded tires. When there’s fresh, soft snow, perhaps up to 4″ or so, they’ll use their inherent ‘floatation’ to ride over the snow without getting bogged down. But in deeper fresh snow they’re going to get stuck quite quickly and it can become difficult to maintain any forward momentum. The emphasis is on floatation and when the conditions do not lend themselves to floating on the surface they become unrideable quite quickly.
Black ice and sheet ice is going to be problematic with any tire.
Sand and mud conditions come with the same limitations. Riding a conventional tire on sand is difficult, as anyone who has tried it will know. The bike wants to slide from under you and go straight when you want it to turn. A Fat tire helps keep you pointed in the right direction and helps stop the bike from slipping out. But when the sand or mud becomes soft, wet and deep, the wide tires can become bogged down.
So use care and common sense in choosing your equipment to match the conditions.
Some of the leading Fat Bike options –
Motobecane Boris X9 Fat Bike
Available from www.bikesdirect.com
The Boris X9 sells at $799 (as of 10/19/2014)
It sells direct with free shipping to your location in the USA. There’s some assembly to do with the fat bike when it arrives, but nothing too technical. You can expect to pay a bike shop around $80 to put the bike together for you.
The Bikes Direct website claim this bike competes with brand name bikes in the $2500 range, which is a fairly extravagant claim. Forum chatter suggests the Motobecane bikes are good value for money but that you pretty much get what you pay for. I’d love to test ride one of these and write a full report, if anyone has one available.
Charge Cooker Maxi Fat Bike
A great entry level option from UK bike designer ‘Charge’. They have two versions of their Cooker bike, the Maxi (shown) retails around $1600 in the USA and a lower-spec version retailing under $1000.
These appear to be great options for starting out on the Fat Bike bandwagon, well built, good equipment for the money and all of the fun of a fat tire bike.
Salsa MukLuk Fat Bike
Salsa have a great reputation for endurance bikes - touring, cross and now this attractive looking Fattie, the MukLuk 3
Surly Pugsley Fat Bike
The grandaddy of Fat Bikes - the Surly Pugsley can be had for around $1800. He’s looking a little bit dated, but then Surly seem to have a bit of a retro look/image going on. This guy is on my personal radar and I may snag one of these puppies before the month is out.
Trek Farley Fat Bike.
I love the Farley. It’s the only Fat Bike I’ve ridden and it’s a bag load of good fun. Prices for the Farley range from around $1800 to $2500 depending on specs and dealer incentives etc.
I’m not a big Trek fan as I think there’s too much of a premium for the name. When you look at Trek’s roadies and some of their Cyclocross bikes and compare them component for component with their leading competitors, they generally come out at least 15% to 20% higher in price.