Mountain bikes have come a long way over the last decade. The technology, components and geometry have evolved exponentially. Part of this evolution includes the various wheel sizes available now and the ability to choose a bike and wheel size to fit the individual's needs.

There used to be one choice, 26-inch wheels, nowadays most adult mountain bikes offer either 27.5-inch (sometimes referred to as 650b) or 29-inch, and recently a combination of the two referred to as ‘mullet’.

The best wheel size largely depends on individual preference, including how you want the bike to feel, the type of terrain you like to ride and your height. Different wheel sizes give different advantages and disadvantages. There is no right or wrong, just individual preference. Read on to learn more about the differences between 27.5- and 29-inch wheels for mountain biking.

I am 170cm (5’6”) and have ridden and raced both 27.5- and 29-inch in enduro and downhill successfully. I still switch between the two depending on the race. Lately I have been spending a bit more time on the Intrigue Advanced Pro 29 which I have absolutely loved for most of my enduro riding, but I go back to the smaller wheels for downhill and dual slalom.

This size suits riders who prefer a more playful ride, with nimble handling, easy maneuverability and fast acceleration. This size suits smaller riders who ride XS and Small frame sizes and many gravity riders (downhill, enduro, park riders).  

• More maneuverable (tight corners): If you favour tight and twisty trails, then you might prefer the 27.5-inch wheels. The smaller-sized wheel is easier to maneuver and handle over technical terrain and tight corners. You have a smaller turning radius for those tight switchbacks compared to a larger wheel, and down steep terrain you won’t be hitting your backside on the rear wheel constantly.

• Lighter weight: A smaller wheel is a lighter wheel. Less material is needed for the rim and tire which can amount to a significant weight difference between 27.5- and 29-inch wheels.

• Faster acceleration: A smaller and lighter wheel will accelerate faster to give the bike a more responsive, snappy, and playful feel. Again, this is great with technical and twisty terrain where there is a lot of slowing down and speeding up, jumping and cornering.

• Better for smaller riders: Smaller wheels will generally suit smaller frames and riders better. There is more space for the seat to drop down, more space for the rider to maneuver around the bike, and less backside contact with the rear tire (very common on a 29er). Also, the wheels are lighter so it is easier for a smaller, lighter rider to pick up and handle.

This size favours riders who want a fast and smooth ride. The larger wheel offers stability with being able to roll over obstacles easily, more traction with an increased contact patch of tire on the ground, and it holds momentum more efficiently once up to speed. This size suits most trail riders, cross-country and enduro racing, and taller riders.  

• Better traction and stability: Larger wheels and tires means that there is more rubber on the ground at one time. A larger contact patch is great for increased traction which will increase grip on roots, rocks and off-camber sections of trail.

• Smoother: 29-inch wheels roll over obstacles more easily including roots, rocks, curbs, bumps, and logs. The larger wheel has an easier time getting up and over things. Therefore many riders experience a smoother ride and feel more confident on larger wheels.

• Holds momentum: Once up to speed, larger wheels are more efficient at holding that speed. Therefore, 29-inch wheels are usually the preferred wheel choice for cross country and longer rides as they require less effort to keep the momentum going.

• Better for taller riders: Taller riders usually prefer the feel of the 29-inch wheel, especially those over 6ft.