Mountain bike wheels used to have only one standard size – 26 inches. That all changed when 29 inch wheels started to become popular in the last 10 to 15 years. While 26 inch wheels are increasingly becoming a thing of the past, 27.5 and 29 inch wheels are the most popular options in mountain biking today.
Mountain bikes with 27.5 inch wheels generally handle better, are more maneuverable and accelerate faster from a standstill, while 29ers roll more smoothly over obstacles, have better traction, and roll faster once at speed.
26 inch wheels – the classic mountain biking wheels
26-inch wheels were long the industry standard for mountain bikes until about a decade or so ago. They have become less and less common in mountain biking over the past 10 to 15 years since the widespread use of 29 inch wheels, and shortly after 27.5 inch wheels, began.
Advantages of 26 inch wheels
- Faster acceleration compared to larger wheels
- Very maneuverable and playful
Because of their smaller size, mountain bikes with 26 inch wheels allow you to accelerate faster and are very playful, provide share handling and are easy to maneuver. This makes them well suited to dirt jumping and for hitting smooth trails with lots of tight turns.
Because of their acceleration and maneuverability, some riders have stuck with 26 inch wheels over more modern, larger wheel sizes to this day.
Disadvantages of 26 inch wheels
- Feel much harsher when rolling over rocks, roots and other obstacles
- Spare 26 inch wheels are getting harder to find
The most obvious disadvantage to 26 inch wheels compared to larger wheel sizes is the fact that they feel much harsher when rolling over rocks, roots and other obstacles, even compared to 27.5 inch wheels.
Another major disadvantage there is to using 26 inch wheels today is the fact that many bikes are no longer made for this wheel size. Most mountain bikes today are offered in either 27.5 inch or 29 inch sizes. This makes it a challenge to find a spare if you’re riding with 26 inch wheels.
27.5 inch wheels
27.5 inch wheels, also known as 650b wheels, became popular after the establishment of 29 inch wheels. Riders were looking for a middle ground in between 26 and 29 inches, that provided a balance between a smooth ride and maneuverability.
Advantages of 27.5 inch wheels
- Smoother roll over obstacles compared to 26 inch wheels
- More maneuverable than 29 inch wheels
- More natural feeling than 29 inch wheels
- Good acceleration
- Playful feel
A major benefit of 27.5 inch wheels on a mountain bike compared to the classic 26 inch wheels is their ability to roll more smoothly over obstacles and rough terrain than 26 inch wheels. This allows you as a rider to pick more aggressive lines and start to thinking about riding over obstacles instead of around them.
They also provide a better rollover capability than 26 inch wheels while maintaining a superior level of maneuverability compared to 29 inch wheels.
The smaller wheels are lighter weight and is easier to execute tight turns on and ride things like switchbacks compared to 29ers.
Some riders also find bikes with 27.5 inch wheels easier to control when hitting dirt jumps, drops, and other technical features, because they are lighter, smaller and more maneuverable.
The 27.5 inch wheels also feel more natural to many riders, especially those mountain bikers who’ve ridden 26 inch wheels in the past.
Disadvantages of 27.5 inch wheels
- Less smooth over obstacles compared to 29 inch wheels
- Require more precise lines compared to 29 inch wheels
A key downside to 27.5 inch wheels compared to their 29-inch counterparts is that they roll less smoothly over obstacles like rocks and roots. While they are a step up from the classic 26 inch wheels in this way, you will still feel significantly more impact from things like rocks and roots than you would on a 29er.
Because of this, you’ll need to choose more precise lines while riding a mountain bike with 27.5 inch wheels. Your cut off for what is “too large” to roll over will be smaller on these wheels compared to 29-inch ones.
Best uses for 27.5 inch wheels
Dirt jumps – 27.5 inch wheels are preferred by many for hitting dirt jumps because they are lighter, smaller, and easier to maneuver in the air.
Downhill – Bikes with a 27.5 inch wheel size work well for downhill because they are snappy and maneuverable for tight turns while still being able to roll over obstacles and rough terrain with relative ease.
Cross country – MTBs sporting 27.5 inch wheels work well for cross country thanks to their balance. They work well on a wide variety of trails, and balance providing decent rollover ability with snappy handling for tight turns.
Smooth trails – These bikes eat up smooth trails and do not face a rollover disadvantage compared to 29ers on these trails.
Winding trails – The improved handling on bikes with 27.5 inch wheels compared to 29ers make them fast and fun on trails that wind through a lot of twists and turns.
29 inch wheels
Advantages of 29 inch wheels
- Roll over obstacles smoothly
- Ability to pick more aggressive lines
- Beginner friendly
- Better traction
- Fast roll speed
- Less flat tires
29 inch wheels are relatively new to the sport of mountain biking, becoming more and more popular since the early 2010s.
Compared to smaller wheel sizes, mountain bikes with 29 inch wheels roll over things like rocks, roots, and other obstacles more smoothly.
They allow riders the freedom to pick more aggressive lines and go over things rather than around them.
This makes 29ers a terrific option for beginner mountain bikers. 29 inch wheels are definitely more forgiving if you hit an obstacle, and allow newer riders to easily roll over many different things they would have to avoid with smaller wheels.
Bikes with 29 inch wheels tend to get less flats than those with smaller wheels, thanks to the shallower angle of the impacts they have when hitting obstacles.
The larger wheels also give them a larger contact patch with the ground, which improves traction of 29ers compared to bikes with 27.5 inch wheels. This makes them a bit more sure footed and better for riding in wet or otherwise slippery conditions, like on snow.
Compared to smaller wheel sizes, 29ers allow for faster roll speeds as well. While they may not be quite as agile as smaller wheel sizes at getting up to speed, they roll faster once they are already at speed. This makes them more efficient at carrying speed through various sections of trail.
Disadvantages of 29 inch wheels
- Less maneuverable compared to smaller wheels
- Tight turns such as switchbacks are more difficult
- Not everybody likes how 29ers feel
29ers do come with some downsides. They are less maneuverable than smaller wheeled bikes. They can be less snappy-feeling around tight turns, and you will likely not be able to rip through smooth yet twisty trails quite as fast as you could on 27.5 or 26 inch wheels.
Also, some people find 29 inch wheels to feel sloppy and clunky compared to smaller wheels. This is a complaint that is more common from seasoned MTBers who were used to the old guard of 26 inch wheels being the standard.
However, bike makers have gotten better and better at fine tuning the geometry on their bikes to allow 29ers to ride well, and many people find them to feel plenty agile out on the trails.
Best uses for 29 inch wheels
Cross country – The larger wheels make 29ers well suited for cross country thanks to their roll speed and ability to smoothly ride over obstacles.
Downhill – 29ers are strong performers in downhill because of how smooth they feel, even at speed, thanks to the larger wheel size. They also provide solid traction because of their larger contact patch.
Beginner riders – The ability to roll over rocks and roots and be less precise with your line makes 29ers well suited to be used by beginner mountain bikers.
MTB racing – Thanks to their roll speed and ability to pick more direct lines, more and more MTB racers, whether that be downhill, enduro or cross country, are choosing bikes with 29 inch wheels.
Rugged terrain – The larger wheels are well suited to roll over rugged terrain more smoothly allowing for improved rider control.
Frequently asked questions
There is no “standard” mountain bike wheel size. There are several mountain bike wheel sizes available to suit a variety of riding styles and rider preferences. Standard wheel sizes available vary between 29 inch, 27.5 inch and 26 inch diameters.
Larger sized wheels are better for riders looking for smoother rides that can roll over obstacles more easily. Smaller wheels are usually handle better on tight turns and are more maneuverable.
Whether an MTB with 27.5 or 29 inch wheels is better for you will come down to rider preference and riding style. You will want to make sure your wheel size feels comfortable for you, and choose a wheel that fits your riding style and the types of trails you ride. If you do a lot of riding on tight, winding trails, you may be better off riding a bike with 27.5 inch wheels.
Alternatively, if you ride a lot of rugged terrain that requires you to roll over rocks and roots often, a 29er likely suits you better.
The size of a mountain biker is not the most important thing in deciding what wheel size they need. Some smaller riders prefer 29ers while other larger riders use bikes with 27.5 inch wheels.
Mountain bike wheel sizes are measured by the diameter of the wheel.
Bigger wheels can be better for mountain biking, especially for their rollover capability, roll speed, and increased traction. This is why 29ers have become more and more popular over the past 10 to 15 years.
Conclusion
As you can see, which mountain bike wheel size you should be riding is more about your riding style and trail preferences than your physical stature. Decide based on the trails you ride, your riding style, and what feels good to you. Do you like to roll over obstacles instead of going around them? A 29er is probably best for you. But if you love riding trails with lots of tight turns, you’re likely better off with a 27.5 inch wheel size.