The 29-inch tires on the columnist’s new mountain bike improve her technical riding skills.

Last year I heard that 26-inch wheels on mountain bikes were going the way of the dinosaur. This year it’s 29ers that appear doomed according to some. Or maybe it’s 2.5-inch-wide mountain bike tires that will fall by the wayside as fat-bike aficionados insist their 4-inch-plus tires aren’t made just for riding over snow.

I bought an expensive (for me) 29er mountain bike two years ago. The bike rocked my world. I love it. I also saved up lots of pennies to buy it, and so I cringe when I hear that 27.5-inch-wheeled bikes are the world’s best or that in a few years people will hang up their mountain bikes in favor of a fat bike they can ride year round.

It reminds me of when my parents bought a Betamax video player a year before it became obsolete, having lost the technology war to VHS. Is the beautiful, shiny, expensive bike I was so proud of a year ago already a relic?

The 26-inch, 27.5-inch (or 650b), 29-inch debate can be broken down into some specific selling points for the various sizes. In a nutshell, 26ers, the original mountain bike size, are known to be nimble and quick. Experienced riders can hop over obstacles, corner at high speeds, accelerate quickly and pump the terrain to gain momentum. But there are some disadvantages, the most important being their ability to roll over rough terrain. Here’s where the 29er gained its enthusiastic adherents.

You can understand the superior rolling power of the 29er by considering the bottom of the tire as a flat plane. When that plane encounters a bump it forms an angle between the top of the bump and where the tire intersects the ground. The steeper that angle, the more difficult it is to go up and over the bump.

Turns out the angle is only 5 percent less for a 29er than a 26er, but over the course of thousands of bumps, that difference adds up. Furthermore, 29ers “flatten out” the bumps by maintaining speed through technical sections, while the smaller wheels tend to lose momentum, so the rider has to use more force to go up and over rock after rock after rock.

That said, it’s easier to hop your tire up and over those rocks when it’s smaller. But that requires a more skilled rider, so the 29er vastly improved the technical riding abilities of people like me.

Twenty-niners also travel farther for each pedal stroke, so presumably you use less energy to cover the same ground. And the geometry of the bike is such that the bottom bracket is 2 inches below the wheel axles, creating a stabilizing effect.

Twenty-niners are the bike world’s Cadillac, 26ers its Ferrari.

In comes the new kid on the block: the 27.5 or 650b. These bikes have actually been around for a while, but when I was buying my bike they weren’t common, so they weren’t on my radar.

I went for the 29er for its rolling capacity, its smoothness and its stability, and I liked what I found. Turns out the 27.5s come pretty darn close to matching these attributes without the downside of feeling big and a little clunky on tight corners.

Bike testers are pretty sold on the way the 27.5s seem to capture the best of both worlds. They say 27.5s feel smaller and nimbler than a 29er but don’t require riders to work as hard to get up and over obstacles as they do on a 26-inch wheeled bike. The 27.5s don’t roll over rough spots quite as well as a 29er but the same testers said that difference wasn’t enough to keep a 27.5 rider off the wheel of someone on a 29er.

Giant, for one, is placing its bets on the 27.5 size. The bike company offers a range of models with 27.5 wheels and only one or two in the other sizes. Giant’s designers have decided that the midsize wheels have all the benefits of their larger and smaller cousins with no real drawbacks.

Maybe if you are racing you are better off on a 29er. And for trick riding the smaller size has distinct advantages. But for the average-size human the 27.5 appears to be the best option, and I’m an average-size human.

But I love my bike with its big tires. I figure as long as I don’t know any better I’m perfectly happy on a 29er even if everybody else is moving toward the smaller size. I’d made peace with this decision until I bumped into Scott Fitzgerald out riding his full-suspension fat-tire bike on the mountain bike trails at Grand Targhee Resort.

Scott said he rarely rides his regular mountain bike anymore. He claims that fat bikes are like fat skis. Everyone scoffed at them when they first came out, and now we all have 100-centimeters underfoot. Sure there are times skinny skis are advantageous — hard, packed, icy groomers, for one — but we ski in the West to avoid those conditions, right? Fat skis are more fun.

And that’s what Scott said. His fat bike is more fun. Ugh. Another reason my fancy bike is obsolete?

I did a little research into the use of fat bikes on mountain bike trails. They have gained some outspoken fans who claim that everything — rocks, roots and sand patches — looks more rideable from the saddle of a fat bike. They are a bit slower and heavier, and don’t corner quite as well as their skinnier-tired cousins, but that doesn’t seem to deter their proponents.

It’s crazy how quickly technology changes, and how the hottest item one year is surpassed by a new innovation the next. It’s true not only of our recreational equipment but also of our computers, cars, clothes. You name it. Your investment loses its glitter the minute you take it out of the package. But you can’t let yourself fall to the hype. New doesn’t always mean better.

Most Americans use only 10 percent of the capacity of their gadgets. I know that is true for me, whether you are talking about my phone, my car or my bicycle. My bike is way better than I am. My riding ability is limited not by my wheel size, but by my lungs, legs and brain. Nothing is going to change that — well, nothing except maybe an electric bike.

Contact Molly Absolon via

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