Best mountain bike wheel size – is 29 or 27.5 right for you?

Your guide to the advantages and drawbacks of each wheel size

How To
Choosing the right mountain bike wheel size is one of the more important decisions for setting up your bike.

Wheel size is an important decision that sets up one of the foundations of the bike.

Editor’s Note: This sponsored post was created in collaboration with Santa Cruz Bicycles.

29 or 27.5 – Which mountain bike wheel size is best?

When you first walk into a bike shop or go online to do some research before buying a new mountain bike, you’re quickly faced with a few key decisions. First, what type of category or bike should you get? Hardtail, cross-country, trail, all-mountain/enduro, downhill, e-bike? After choosing the category that’s right for you, your second choice should be wheel size.

Which wheel size is right for you? There are a number of factors that go into selecting the right mountain bike wheel size. We’ll help you navigate the underlying qualities of diameter, evaluate the pros and cons of each, and arm you with the tools to help decide which is right for you.

Here are some of the main factors to consider when determining the proper mountain bike wheel size for you:

  • Riding style
  • X-factors, like rider height
  • “Mullet setups”
  • What to do if you’re upgrading from a 26er

Related: How to Pick the Right Mountain Bike Tire

When it comes to mountain bike wheel size, 27.5 wheels are a good tool for riders who are motivated to go sideways on the ground or in the air.

27.5 wheels are a good tool for riders who are motivated to go sideways on the ground or in the air.

27.5 – The agile and playful one

This is used to be the middle mountain bike wheel size, but with the decline of the 26-inch option, 27.5 is now the smaller wheel. In a nutshell, it’s best characterized as the fun-sized wheel size and its resume will include adjectives like “agile,” “playful,” and “nimble.” It’s a versatile wheel size as well, fitting more riders, especially those shorter in stature. And it can handle a wider array of tires and suspension travel. With lighter wheels and tires, it’s easier to change speeds and accelerate with less effort.

The downside is that 27.5-inch wheels don’t maintain as much momentum as 29-inch wheels. The smaller diameter means they don’t roll over trail obstacles as easily. For these reasons, they can be slower on many courses, and with a smaller tire contact patch, there’s less traction compared to their big-wheeled brethren.

When it comes to mountain bike wheel size, covering lots of ground efficiently is the 29er's domain.

Covering lots of ground efficiently is the 29er’s domain

29 – The fast one that plows over things

The larger mountain bike wheel size, 29-inch wheels, provides the best confidence, especially at speed. Bikes with larger diameter wheels generally feel more stable and cover ground faster, as they hold their line over rough terrain and roll over obstacles with less effort. Once up to speed, 29-inch wheels maintain their momentum better. Making them faster in many, but not all, situations. With a bigger tire contact patch, 29-inch wheels have better climbing, braking, and cornering traction as well.

On the downside, 29-inch wheels take more effort to accelerate, so changes in speed are less efficient than 27.5 counterparts. Since 29ers carry more momentum and generally have longer wheelbases to accommodate the larger wheels, they are not as nimble as mountain bikes with 27.5-inch wheels.

There is one genetic human attribute that affects the mountain bike wheel size choice and that is rider height.

X-Factors – rider height, style bike/e-bike weight, component availability

There is one genetic human attribute that affects the mountain bike wheel size choice and that is rider height. Since we were toddlers learning to ride we’ve increased wheel size to fit our proportions. A 27.5-inch bike is more proportioned for shorter riders and 29-inch wheels for taller riders. Luckily, there is a wide crossover in the middle—from about 5’5” to 6’2” is where a rider can comfortably choose either wheel size. Under 5’5″ is generally 27.5 jurisdiction and above 6’2” is fit by 29-inch bikes best. You’ll see this in many manufacturers as their extra small sizes are only available in the 27.5 sizes.

When it comes to riding style, mountain bikers who love to play and pop over rocks, roots, and other trail features will find that 27.5-inch wheels are a better fit. A bike with smaller wheels is generally easier to throw around and requires less effort to change directions. For the riders who like to go fast, maintain speed and plow over things, a bike with 29-inch wheels is a very willing partner.

Mountain bike wheel size is a tool that can be harnessed to make an ebike more nimble.

Wheel size is a tool that can be harnessed to make an ebike more nimble.

As far as e-bikes are concerned, the motor usually takes up some chainstay real estate, resulting in slower handling. And an extra 15+ lbs of motor and battery weight hinder the agility of the bike as well. So a 27.5 wheel, especially in the rear, helps e-bikes regain some of the lost handling and agility.

Keep in mind that these are rough guidelines to help you get started and that there are exceptions to every rule.

Related: How to Service Santa Cruz Suspension Linkages

On one of our ebikes, we experimented with a mullet 27.5 rear and 29er front setup to see which mountain bike wheel size works best.

On one of our ebikes, we experimented with a mullet 27.5 rear and 29er front setup.

29 front and 27.5 rear, aka, “mullet setups”

Some bike brands are experimenting with 29-inch front wheels paired with 27.5-inch rear wheels. These mixed wheel size bikes fill a void and offer a novel solution. If the 29 excels in speed and 27.5 in style, how about a combo platter that provides speed and style?  Front end composure and rollover, good rear end agility, and less rotational weight, as well as some additional butt clearance when the suspension bottoms out, are some of the benefits of mixed wheel size mountain bikes.

Does it really work? Indeed it does, but careful engineering is required to optimize this configuration. Head and seat angles as well as the bottom bracket heights need to be accounted—just swapping in a 27.5-inch rear wheel into a 29er won’t provide the best mix of both. The chainstays need to be made specifically for the 27.5 wheel to take advantage of the agility the smaller wheel offers.

As mentioned above with 27.5 wheels, the mullet configuration can be a solution for e-bikes, which are typically less agile and more difficult to change direction with. The motor and battery add about 15+ lbs of bottom bracket weight. Also, the motor often takes up valuable real estate that results in longer chainstays.

When it comes to mountain bike wheel size, the choice these days is between a 27.5 and a 29 inch wheel.

The choice for a mountain bike these days is between a 27.5 and a 29 inch wheel

What about my 26er?

If you’re upgrading from a bike that is at least 10 years old, you may have a 26-inch bike. That wheel size has mostly been abandoned and is now seeing duty in kids bikes and dirt jump bikes. The latest forks, wheels, and tires are no longer available for the 26er wheel size, so one must upgrade to either 27.5 or 29. But have no fear, the new mountain bike wheel sizes are better in every aspect described above compared to the trusty 26er. But one has to choose which direction to go with.

During the Lenzerheide UCI MTB World Cup stop in Switzerland.

Bottom Line

Hopefully, we’ve armed you with some of the key considerations in making a decision on mountain bike wheel size. The 27.5-inch wheel is ideal for popping over stuff, changing speeds and direction, and playing with the trail. The 29er is best for going fast and winning races. It covers ground well, stays planted, and plows over obstacles.

These baseline attributes serve as a starting point and the rider can make a personal choice and make either wheel fit their style and preference.

What is your current wheel size choice and what is the size for your next bike?


About the author: Francis Cebedo

The founder of mtbr and roadbikereview, Francis Cebedo believes that every cyclist has a lot to teach and a lot to learn. "Our websites are communal hubs for sharing cycling experiences, trading adventure stories, and passing along product information and opinions." Francis' favorite bike is the last bike he rode, whether it's a dirt jumper, singlespeed, trail bike, lugged commuter or ultralight carbon road steed. Indeed, Francis loves cycling in all its forms and is happiest when infecting others with that same passion. Francis also believes that IPA will save America.



Comments:

  • raphael says:

    If I could, my next bike will have 26″ tires. I am short and 26″ set ups are lighter and stronger than bigger sizes

    • Shredman says:

      I agree. I’ve been running 26+, (26 x 2.8 DHRII on 40i LB rims) for a few years and I love it! They are actually 27.5 in diameter and 2.75 wide at the tread edge to edge, but still a light strong wheel.

    • Sophie says:

      I’ve got a pristine, super fun 26″ mojo for sale if you’re interested, Raphael,

  • dan says:

    how is this still a topic of interest???? haven’t all those questions been answered 50 million times by everyone on the planet in the last 5 years when this whole 26 x 27.5 x 29 started?

    • Francis Cebedo says:

      Definitely still of interest as the public shifts from 70% 27.5 to currently about 70% 29er. And there is a massive new influx of new mountain bikers brought about but the Shelter In Place. They don’t know wheelsize, boost, droppers and are hungry to understand them as they buy out all the bikes.

  • Bensonc says:

    How about plus tire?? Specifically, are 27.5+ really same as 29??

  • Vaughan Lowe says:

    yeh,,, 27.5 is good for play time at the park,, but the 29er certainly climbs better. Hence,,, you need both.. my choice is 27.5 hard tail for straight out fun, and a 29er full sus for the longer trail riding… good times and your bikes last twice as long… 👍

  • Andrew says:

    26 inch.
    I’m more interested in a lighter bike and a more agile fun bike than powering over bumps in difficult terrain.

  • West says:

    I live in TX and the local trails are mostly rock where fatter tires tend to fare better in terms of a less jarring ride and better traction; would be interesting to hear your opinion about the fatter tires like 27.5+ and 29+ and of course the 26″ fat tire when it comes to rock-laden trails.

  • Road MTBer says:

    i think 27.5 look better, it’s very “balanced look”.
    29er seems too big

  • Ency says:

    At 6 ft, I prefer 29ers over 26ers for sure. One ride (over ten years ago) and I never ride 26ers again. I am faster but I feel far more stable on fast downhills as well. They are just more fun for me. That was maybe 2008. I never really liked 27.5 but I JUST picked up a 27.5+ to add to my collection of 29ers and it is a blast. I don’t feel as confident in slower tech stuff but it has gobs of traction on loose trails so it is fun! It is maybe 90% as good in slow chance so the 29er still rules and it is 90% as fast but it is more nimble n tight trails too. 26 is effectively dead…no denying that. 27.5+ is dying too but I have a nice stock of tires and it is a great complement to my love for 29ers. I’ll try a nice 27.5 with maybe 2.4 or 2.5 tires this year. Maybe I will not dislike them like I did 26ers after I rode my first 29er. My first 29er was a Moots YBB. Well, I also had a Titus Racer-X 29 at practically the same time. They rekindled my love for mountain biking.

  • Brad says:

    This article is just rehashing fallacies that the bike industry keeps pushing. 29er wheels are purely slower everywhere. Their moment of inertia is concentrated at a bigger radius than the 27.7 or 26er wheel. That means they require more energy to get up to the same speed.Bicycles don’t travel fast enough for the momentum to be a big deal. The contact patch area fallacy is another one. The differences are negligible and often overshadowed by tyre construction and pressure. Really? Please stop selling BS.

    • Francis Cebedo says:

      Will have to absolutely disagree with you there. 29ers are now used for XC racing almost exclusively from Amateur to Pro. The reason is they are faster and the purpose of racing is fundamentally to go faster and win. When there is a lot of start and stop, the advantage decreases.

      As far as the contact patch, the difference is not negligible as it is clearly a percentage difference. Keep tire design and compound the same to stop confusing the subject.

      And no need to pull the ‘bike industry’ bogeyman. It’s just riders buying and riding bikes and forming their own opinion. And there’s science too.

    • Karl says:

      I’d phrase things nicer but you make an important point. All things being equal re: the rim model, tires, hubs etc., the 29er wheel will be heavier. Slower acceleration, it’ll run slower (i.e. lower top end). So you need to shell out for the lighter parts, quite considerably so. You may not be able to make up the difference if you run sturdier tires. You also want wider hub flanges to the get the same level of lateral stiffness. Cannondale I believe counters that somewhat with their proprietary offset at the rear wheel.
      Sum of it, 29er with the lighter parts plays out well in XC, but trail bikes and on I think I prefer 27.5, for stiffness and the sturdier tires having less of a weight penalty

    • Jason says:

      why are races mostly won with 29s?

  • Wilson Barayoga says:

    My MTB is 27.5 and its realy good fit to my height.

    • Francis Cebedo says:

      >> My MTB is 27.5 and its realy good fit to my height.

      What is your height? That is indeed a key consideration for wheel size.

  • Shawn says:

    I’m 6’1″ and I prefer 27.5″ wheels most of the time. To each their own.

    • Francis Cebedo says:

      After all the science, fit, and riding style and purpose are taken into account, personal choice has the veto power.

  • KW says:

    I love my 28.25er. 27.5 FS bike with 2.35 tires on 30mm ID rims. Great handling and great rollover.

    • Francis Cebedo says:

      >> I love my 28.25er. 27.5 FS bike with 2.35 tires on 30mm ID rims. Great handling and great rollover.
      Yup! These 2.6 tires on wide rims are offering new and exciting options now!!! Much flexibility.

  • Iridegravelwithmymountainbike says:

    What’s really missing from this article is to advise the bike buyer to test ride both on the trails they ride. This is what closed the deal for me. When helping my friend select a mountain bike I had her ride both sizes. She immediately said she didn’t like the 29er after taking it about 15 feet, so I got her the 27.5 and she was happy.

    • Francis Cebedo says:

      >> What’s really missing from this article is to advise the bike buyer to test ride…

      For sure this is the ultimate. A couple caveats though:
      – very, very hard to do this on a real trail these days, especially the same trail. The Outerbike model was ideal since one could test many bikes in one day.
      – the rider will feel more comfortable on the bike with wheels closer to what they currently ride. So for most riders coming from a 26, a 27.5 will feel great right away while a 29 bike will ake 3-4 real rides to get used to.

  • Iridegravelwithmymountainbike says:

    This webpage has some good information on wheel size selection
    https://www.giant-bicycles.com/int/technology/detail/94

  • justwan naride says:

    I own an older XC 26″ and a modern trail 27.5″, both hardtails. Apart from the wheelsize their geometry is very different, with the older bike being steep and compact and the newer one being low and slack with a longer travel fork. Without a doubt the 27.5 is faster around a XC course, more stable at speed, keeps momentum over rough terrain better. The same holds for 29″ vs 27.5″. On the other hand, my old 26er, built a bit like a 4X bike is a lot of fun on smooth, flow, pumpy trails. Still not faster, but the quick response and terrain feedback make it very involving and satisfying. On rough natural trails these traits make it harder to ride compared to something with bigger wheels. As for the ultimate in alround speed and capability I’d go with a mullet setup. I’ve used my trail ht as a mullet and confidence went up without any loss in agility. There were important geometry compromises as the bike wasn’t designed for this though, but it was a good experiment. At 5’4″, I’d totally buy a mullet that was designed as such and not a modified 29″ or 27.5″.

  • 🤔😳🤦🏻‍♂️ says:

    I almost stopped reading this article not so much because topic has been so heavily compared and reviewed for 5 plus years, but because once again they don’t fully understand the rolling dynamics that make up the impact. Don’t get me wrong they got a lot of things rite here, but the part about 29s having more tire and wheel weight than 27 and hurts acceleration is flat out wrong! They are essentially dynamically the SAME. Why?? Because the added weight is proportional to the reduced angular velocity needed to be at the same speed because the total wheel height is different and is what is causing the change on weight. For example 27.5 * 3.14=86.35 vs 29 * 3.14= 91.06 inches for one revolution. That means the 29 turns exactly that much less for the same speed, it’s a wash. 5% reduction in turns for a 5% increase in weight. 😄 The dynamic wheel weight on the outer perimeter matters the most. The net weight of the wheel after the wash out is insignificant.

  • Johnny says:

    I mostly rode a 26″ DJ bike since 2001, and sometimes rode a 26″ rocky mountain switch over the past decade. Sold the switch and got a 27.5 meta am and I feel extremely confident in the trails but can’t bunny hop, manual, or do really any fancy dancy stuff on it. More like full throttle and go (it’s fun but hard to be precise).

    Getting a 29″ would be just silly unless you are a complete xc nut or a dh racer. I’m 5’9″ so I’m sort of in that middle ground, always liked smallish/med bikes, feel comfy on a 24″ BMX in my mid thirties.

  • Slohr says:

    Just bought a 27.5″ 150-140 bike as my first full suspension because it felt light (even though it is 30#) on the trail. Been riding exclusively 29″ for 12 years. Only 2 rides on the 27.5 with 2.5″ and 2.4″ tires, but I find the pick up and maneuverability exceeds the benefits of the sustained rolling speed of the 29er (could be new bike syndrome). But it’s really splitting hairs. So far the 27.5 FS climbed a rocky trail faster than my 29er with 2.4s, but both bikes were much slower than my heavier rigid ROS 9+, 29×3″.

  • Jim D says:

    24” tires all the way

  • Sean says:

    I still find this all silly too. I still ride a 26er. I tried a friend’s new 27.5 bike and it felt like the wheel base was overly long, like when Gary Fisher started this trend of long frames and short stems…his company was absorbed. Most of the time I read that 29ers are better i imagine its coming from someone 6′ or taller who likes trails you could complete on a cross bike. In case anyone want to keep going down this silly one size fits all and bigger is better trend, they do make 36ers. I find it BS that we don’t have different wheel sizes for different sized people…you know, like when you buy your kid a bike. 26ers and their parts disappeared because bike suspension hasn’t improved that much and bike weight, with exception to carbon rims havent changed much so the industry forced people to “upgrade” to bikes with slightly different dimensions (don’t get me started on hub widths). The only exciting thing I see on the horizon that will make me “upgrade ” is the new pinion gear drive train or something equivalent that is truly new… this wheel size debate for all is rubbish and shouldn’t be the main thing driving your purchase decision.

  • Jeff says:

    An coordinated effort by the bicycle industry to make everyone who was perfectly happy with 26″ wheels to buy new wheelsets, frames, forks, tires, etc.

  • Goffredo says:

    Hmm. That rider in the red jacket looks like he’s bombing down Zane Grey trail, and the Heckler e-bike looks like it’s sitting on that tree stump at the intersection of Pipe Dream and the top of the northern HW9 drops like Felix / Sweetness. I kind of miss Santa Cruz. Except all the crack heads.

  • DANNA BROWN says:

    ” many manufacturers as their extra small sizes are only available in the 27.5 sizes.” Really? can you tell me who those are? I can’t find a lightweight, short travel bike in a 27.5. I”m 5’2″ and don’t want to move straight from 26 to 29. Thanks!

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