What’s going on with mountain bike wheel sizes and how does it affect us female riders? Our 29er mountain bike buyer’s guide is here to fill you in…
Mountain biking is currently in the throes of a technical shift as the wheel size we’ve used since the 70s is joined or supplanted – depending on who you believe – by another two sizes.
Mountain bikes have had 26-inch wheels since the original clunkers were constructed from adapted Schwinn beach cruisers. Nobody took a conscious decision to use that size rather than any other, though. Mountain bikes needed really fat tyres for traction and cushioning and tyres over two inches wide only came in 26in.
Because 26-inch wheels are relatively small, mountain bike manufacturers were fairly easily able to accommodate almost all sizes of riders, from tall blokes to diminutive women.
About ten years ago, a few pioneers started experimenting with larger wheels, building mountain bikes with the 700C wheels used on road bikes. With a two-inch tyre these wheels end up about 29 inches from tread to tread and the wheels gave the new bikes their name: 29-inch bikes, 29ers for short.
A ten year argument followed about the advantages and disadvantages of the new size. Evangelists made bold, often excessive claims about the faster and increased traction of the larger wheels, while sceptics rubbished 29-inch bikes for being ponderous and heavy.
Before reading on about the advantages and disadvantages of 29er mountain bikes, check out these options if you’re also looking to buy some new kit for the trials:
Advantages of 29er Mountain Bikes
Faster: Larger wheels roll faster, that’s a matter of the physics of tyres.
Smoother ride: They are also less prone to fall into holes in the trail, so a 29er smooths out the ride.
Improved traction: Because the tyre’s contact patch is longer, there are usually a couple of extra tyre tread blocks in contact with the ground, so traction is slightly improved.
Those advantages make 29er mountain bikes great for most types of riding, and especially for fast, endurance rides. Beginners also benefit, because a 29er’s forgiving ride on rough surfaces makes it easier to learn to ride off road.
Disadvantages of 29er Mountain Bikes
The disadvantages come from the sheer size of the wheels.
Taller: A wheel that’s three inches bigger inevitably raises the front end of the bike. This presents challenges getting the handlebars low enough for smaller riders and certain types of mountain biking.
Heavier: Big wheels are unavoidably heavier, and any technological tweak that helps makes them lighter can also be applied to 26-inch wheels.
Slower acceleration: The extra weight makes them slightly slower to accelerate than a 26er, in theory at least. In practice, on rough surfaces, it feels like the ride-smoothing effect swamps this.
Poor handling: The ponderous handling of early 29ers was down to poor steering geometry. With your eyes closed, it’s now hard to tell a 29er from a 26er because bike designers have dusted off their textbooks and rediscovered the equations that determine good bike handling.
What about us girls?
When 29er mountain bikes first appeared, some said they were best for riders over 5ft 8in, which eliminated about 90 percent of women.
Smaller riders, the thinking went, would not be able to get 29ers that fit them well because the extra height of the wheel pushes the handlebars up.
Ultra-short head tubes and zero-rise or even dropped stems have helped, and there are now plenty of small-framed 29er mountain bikes. Specialized’s new Rumor, for example is offered in a size S with a 15-inch seat tube.
Compared to the bike shapes we’re used to, small mountain bikes with 29-inch wheels do look a bit odd. In fact, let’s be honest some of them are downright ugly. But they ride brilliantly, providing all the confidence and easy-rolling benefits of 29ers in a female-friendly package.
The Inbetweener: 27.5-inch
Larger wheels also give suspension designers headaches as they try and design 29er mountain bikes with more than about five inches of rear wheel travel.
To get round both the bar height and suspension travel problems, an intermediate size has emerged.
Dubbed 27.5-inch, it’s based on a rim that’s in between the classic mountain bike 26-inch size and the 700C/29-inch size.
(If you want to delve deeply into the mess of systems and terminology that describes bike tyre sizes, Sheldon Brown’s website is a good place to start.)
27.5-inch mountain bikes give smaller riders and long-travel suspension bikes some of the faster-rolling advantages of 29ers, and look set to carve a niche for some applications.
Unless you’re into one of those niches, which generally involve riding down technical trails as fast as possible, a 29er mountain bike is almost certainly the way to go if you’re buying a new bike.
For general mountain biking and especially for cross-country and endurance racing, they’ve proven themselves superior in both speed and user-friendliness.
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