What’s The Best Mountain Bike Wheel Size? 

Mountain biking sees constant change, and the evolution and variety of wheel sizes out there is one example of this. The 26” has been the standard size for decades, and it worked well. But the relatively recent introduction of the 27.5”/650B, 29”, and Plus sizes, has effectively challenged the dominance of the 26”.

We’re going to give you a rundown of various wheel sizes, and highlight why we think 27.5″ is a clear winner…

26-inch Wheels

The original size for MTB wheels, the 26” has been around since the 1970s. You’ll still see plenty of riders on 26-inch wheels today. However, they’re now facing a lot more competition from larger sizes, which can have performance benefits over these smaller wheels.

Just a reminder – wheel size is measured from tyre edge to tyre edge. But of course, tyre height can vary, so it’s rare that, for example, a 26” will be precisely 26”. One of the best things going for 26″ MTB wheels is how nimble they are – they’re great for twisty tracks. Another benefit is a faster rate of acceleration on smooth surfaces, coupled with a lighter weight due to the short diameter.

Having been around for so long, there’s no shortage of 26” wheels, components and spares around. If you break a 26”, you’ll probably be able to get a repair or replacement pretty easily. The same with components – you could get relatively cheap upgrades as there are so many 26” components out there.

However, there’s much less rollover ability than you’ll get with the larger sizes. Hitting obstacles at a steeper angle than on a 29er or 650B means it’s harder to roll over them. Because of this, and the fact you’ll be dipping into holes more easily, you’ll lose speed on rough terrain faster.

27.5-inch Wheels / 650B (584 mm)

27.5”/650B appeared around 2012 as an attempt to combine the benefits of both 26” and 29″. At first, they appeared to be a relatively niche choice, but they’ve continued to gain popularity.

As wheel size is measured from edge of tyre to edge of tyre, you could actually get an idea of what riding 27.5” wheels would be like by fitting high profile tyres on a 26” wheel. Indeed, many see the 650B as a natural progression from the smaller size.

The 27.5” wheel has a number of benefits and is a good middle ground between 26″ and a 29er. They have the quick acceleration of 26” wheels that you’ll find lacking on 29ers, but you’ll feel a notably smoother roll – much like you would on 29” wheels. It’s this improved rollover, without sacrificing much in the way of manoeuvrability, that makes 650B wheels so appealing. Additionally, a lot of smaller riders can be put off 29ers by their ‘ungainly’ look, but the 27.5 can look like a better fit.

So, are 650B wheels truly the best of both worlds?

Perhaps. When they first came out, they were understandably on the pricey side, as were components like tyres and frames, as there were few about to meet the new wheel size. This is much less of an issue these days. If you’re considering a change from 26” wheels, moving up to 27.5” is a fairly natural progression. The 27.5” wheel size hasn’t stopped here though – it’s also possible to get 27.5” Plus.

27.5 Inch Plus Wheels

In the constantly evolving world of mountain bike wheels, the introduction of Plus sizes has been one of the most recent developments. Simply put, they’re wheels that have the same internal diameter, but are wider. Although you can get 29+ and even 26+ MTB wheels, they’re most common on 27.5” wheels.

The main benefit of Plus wheels is the increased grip they offer. You could see them as trying to emulate the grip of a fat bike’s tyres on a smaller wheel. With a wider tyre, you’ll get more traction, but you won’t lose much in the way of rolling resistance.

Unsurprisingly, Plus wheels are heavier, so you’ll potentially experience a less nimble ride with slower handling. If you want more stability, it’s worth considering a Plus wheel; this added stability can improve confidence. Or, if you ride on a lot of loose terrain, go for Plus. But if you ride on mostly smooth terrain and are a confident rider, they may not be worth the extra drag.

29-inch Wheels (622 mm)

When they first came about, 29-inch wheels caused quite a stir, but 29ers are getting more and more popular with pros and amateurs alike, and an increasing number of races are won on these big wheelers. They’re still widely used on XC bikes, where they were first used, but are increasingly used on downhill bikes too.

If you’re considering making the switch to a 29er, there’s a number of advantages and disadvantages to consider.

Arguably the main benefit of a 29in is their ability to roll over objects with ease. This is simply due to their size – obstacles hit the wheel at a lower point than on a small wheel, so it’s easier for a 29er to roll over it. As such, these wheels will give you a more comfortable ride on bumpy terrain. They also allow you to ride on ground that may even have been out of bounds on smaller wheels. This is nothing to be sniffed at, as increased comfort and confidence on rough ground could lead to you riding faster.

Once at cruising speed, you’ll find that 29ers are more efficient at maintaining this speed, as they carry momentum better. However, perhaps unsurprisingly, the size of the wheels has some drawbacks in terms of acceleration. Because 29” wheels have greater rotating mass and tend to weigh more than smaller wheels, acceleration is less rapid. So whilst you may find it easier to maintain cruising speed, it can take longer to accelerate to reach this speed in the first place.

If you’re concerned primarily with tight and ultra-responsive handling, 26” wheels are more manoeuvrable than 29ers.

Some riders are also put off for aesthetic reasons – admittedly, these big wheelers can make the bike look ungainly and the rider look small. If you’re a taller rider, the issues of proportion aren’t going to be much of an issue.

Races continue to be won on 29” wheels and developments in technology continue to be promising. They’re increasingly popular with riders these days, and especially if you’re after a soft roll, they could be worth considering.

Fat bikes

Admittedly, these are definitely not one of the ‘standard’ bikes you’ll see out on trails. With 4-5” wide tyres, you’ll know a fat bike when you see one. With such a wide surface area, these tyres have great grip, and run on low pressure. This makes them ideally suited for adventurous terrains like snow and sand. Undeniably good fun, riding on snow or sand is also great for your fitness. For those with a sense of adventure looking to ride where a normal MTB can’t go, look no further!

So, What’s The Best Wheel Size For A Mountain Bike?

Ultimately, it really depends on your requirements.

26” has been the standard for years, and currently, they’re cheaper and easier to repair or replace than larger sizes. The agility of a 26” is slightly compromised by the poor rollover ability.

That’s why the 27.5” wheel is becoming so popular. Combining the nimble handling of the smaller size with the more comfortable ride and better rollover of the 29er, they make an ideal middle ground. The 29” is similarly gaining traction (no pun intended) in the MTB community, as more riders start to appreciate big wheelers’ improved ability to maintain cruising speed and roll over obstacles.

Have a think about the sort of terrain you’re riding most frequently, and ride it on different wheel sizes. You’ll soon find out what you prefer.