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For decades, since they first gained popularity in the 1970s and ’80s, mountain bikes have been called fat-tire bikes. Which makes sense, comparing their wider, knobby tires with the thin, high-pressure tires employed by road cyclists.

But today, a new generation of mountain bikes is taking the concept of “fat tires” to an entirely different level. These “fat bikes,” equipped with either 26-inch or 29-inch wheels, feature tires ranging in diameter from 3.5 to 5 inches that work equally well on sandy beaches and snowy trails.

“Any bike that puts a smile on your face is a bike worth riding,” said Brian McInnis, owner of JRA Cycles in Medford. “Fat bikes do that. It’s not always quantifiable as to why, but they do.


“It’s a different experience than riding a regular full-suspension bike,” McInnis added. “The tires can be smashed into anything, and all that happens is you get bounced in a different direction. Once you understand the physics of how this bike rides, you can use it for a unique and exciting ride experience.”

The “physics” results from the cushioning effect of the fat bike’s low tire pressure. Road tires will typically run between 100 and 125 pounds per square inch, or PSI, and mountain bikes range between 25 and 60 PSI (depending on terrain and suspension choice). Fat bike riders, however, typically run their tires with less than 10 PSI, giving them plenty of bounce.

With their ridiculously oversized tires, fat bikes almost look like clown bikes, until you try one on for size. And then you’ll be hooked, say converts.

“They are just so much fun,” said professional cyclist Tim Johnson of Beverly, who has made his living racing mountain, road, and cyclocross bikes. “It’s like a light tank.”

Fat bikes can be made from a variety of materials, including steel, aluminum, titanium, or carbon fiber, and typically have disc brakes. You can find them with or without front and rear suspension, and in single-speed and multi-gear models. Expect to pay anywhere from $800 up to $6,000 for custom models (the average is in the $2,500 range, according to McInnis).


“Fat bikes are now another year-round option for anyone thinking of trail riding,” said Philip Keyes of Acton, executive director of the New England Mountain Bike Association. “They’re amazingly stable, yet nimble. [They] offer incredible traction and control, and are extremely comfortable due to their upright posture and cushy tires. Fat bikes aren’t snow bikes; they’re mountain bikes. And many – including myself – ride them year-round.”

However, winter is when most fat bike enthusiasts add this new rig to the stable.

“The main attraction was to extend the riding season by being able to ride on snow,” said Alexis Arapoff of Stow. “I would always be looking to ride my mountain bike in the winter, but with a regular bike you needed the snow to get really packed and frozen to make it possible. The fat bike gives you the ability to ride more in the winter, but the snow still needs to be packed.”

After his 29-inch mountain bike was stolen, Lee Apgar opted for a fat bike, a full-suspension Salsa Bucksaw 2.

“The wider tires seem to float over or through obstacles much easier than on my old 29er, which in turn rolled more easily over stuff than my old 26 regular tire bike,” said Apgar, a Wenham resident.


“The Salsa was designed to be an all-around bike. Probably not a pure ‘beach bike,’ with the 4-inch instead of 5-inch tires, but I’ve ridden a few times on the beach and it handles hard and soft sand very nicely.”

The bikes, however, aren’t ideal for every situation. For starters, they carry a weight penalty. While a race-ready mountain bike typically tips the scales at just over 20 pounds, a typical fat bike will weigh in the 30-35 pound range. And they can be sluggish.

“You can ride surfaces that bog down smaller tires. On dirt, the traction is unbelievable,” said Dan Streeter of Newbury. “That leads to a different riding style for me than a regular mountain bike, with less momentum riding up stuff, and more of a slow ‘tractor’ uphill.

“They’re heavy, so they’re not great for long rides unless you’re really fit,” Streeter said. “You may have trouble keeping up on a group ride, but this hasn’t been a big problem for me on reasonable terrain.”

The wheels themselves also weigh more, which translates to a more strenuous workout when you account for the physics of rotating mass.

“On flat terrain it’s not an issue, but on hillier terrain the weight of the rims and tires is noticeable,” said Arapoff. “That being said, there are many situations where the fat bike has an advantage; climbs with poor traction — slippery roots or loose surfaces — are often no problem on the fat bike. The tires have a significantly larger contact patch that allows you to roll over the rough terrain.”


Clearly, the benefits of these bikes outweigh any drawbacks.

“The traction is unbelievable,” said Michael Dube, a North Attleborough native now living in Sandwich. “The bike controls itself and gives you great confidence when riding.

Fat bikes are so forgiving that many enthusiasts consider them the perfect family-friendly two-wheeler.

“I will be getting another fat bike for my bride to ride,” Apgar said. “While she may not want to go bashing around on single-track in the woods, she would thoroughly enjoy riding with me on the beach.”

Brion O’Connor can be reached a brionoc@verizon.net.