What to Look for in Mountain Bike Wheels

The bottom line: Don't stress out over size

Mar 18, 2016
Outside Magazine
What to Look for in Mountain Bike Wheels

Don't overthink the wheel size debate.    Photo: Stan; Reynolds

Mountain Biking 101

Read our complete guide on buying your first mountain bike.

Bike nerds like to spin out over wheel size debates, but the truth is this: no matter what wheel size you buy, it will work great and you’ll have tons of fun. Don’t stress out over it. 

27.5 vs. 29

Mountain bikes today come built around one of two wheel sizes: 27.5 inch (still also commonly referred to as 650B) and 29 inch. These have largely replaced the 26 inch, which was the standard for years and can still be found, especially on budget bikes. We’d suggest avoiding 26, not out of any dislike for it, but simply because the industry has mostly moved on, making parts and tires for the size becoming difficult to find.

The difference between 27.5 and 29 is subtle. The 29er’s additional circumference means it takes more energy to get up to speed, but it carries momentum better and rolls over obstacles easier. The size also provides a larger contact patch of rubber, which equates to more traction. On the other side, 27.5ers tend to be a bit more nimble because there’s less rotating mass to move around. 

In our experience, new riders benefit more from the additional confidence, ease, and traction afforded by 29ers. But the bottom line is that either size works fine, and the best reason to choose one over the other is fit. If you have the choice, try both options and go for the one that feels better.  

Plus-Size (27.5+ and 29+) 

The other big conversation in wheels right now is plus-size, which refers to using wider tires to get some of the same rollover, traction, and momentum benefits that 29 offers over 27.5. 

On a 27.5+ setup, three-inch-wide tires mounted on 27.5-inch diameter rims give you the same effective size as a 29er with 2.3-inch tires, but you get broader contact with the ground for better grip, as well as the ability to run lower tire pressures. Specialized nailed this design with its Fuse

Even bigger is the 29+, like the Trek Stache, the Surly Krampus, and the Niner ROS9+, with three-inch tires on 29-inch rims for even more bulldozing and traction. 

The downside to the plus-size movement is that the added tire weight can make for heavy rides, especially in the budget models, where wheels tend to be heavy. We do feel that new riders benefit from the increased tire size, and we like the versatility of extra clearance, but it’s also worth realizing that we’re just at the front of this trend and designs are certain to change and evolve in the next few years.


No matter what size wheel you choose, one of the single best improvements you can make to any bike is a wheel upgrade. That’s especially true on budget bikes, where manufacturers save expense by spec’ing heavy hoops. Since rotating weight is some of the most noticeable heft on a bike, lightening up your wheelset can make a dramatic improvement in how a bike rides and feels. 

Carbon wheels, such as the Reynolds Black Label models, are the epitome of performance, but a good set of aluminum rims like the Stan’s Arch EX save nearly as much weight and cost a quarter of the price. 

One last note: No matter what wheels you are running, take the time to set them up tubeless. The lower pressures this allows makes for a much better ride.

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