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What Is a 27.5 Bike?

an image of a 27.5 inch mountain bike
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    An Introduction to 27.5 Bikes

    I assume you’ve come here to learn a little more about 27.5 Bikes, and you’ve come to the right place. 

    In recent years mountain bikes have souped up with electric motors and more suspension travel. But what is a 27.5 bike? what do these numbers mean? and which is better 27.5 vs 29er?

    By the end of this short guide, you’ll be a 27.5 mountain bike expert. I’ll also help you understand which bike is more suitable for your riding style; a 27.5 or a 29 mtb.

    Let’s hit the trail!

    What Is a 27.5 Bike?

    A mountain bike with wheels that are approximately 27.5 inches in diameter is typically referred to as a 27.5 bike and sometimes called a “tweener.”

    A 27.5 bike fits in between the traditional 26-inch wheels and the 29ers with even larger wheel sizes. 

    While the size of the wheel affects the handling and control of the bike, it is not the only design characteristic that sets a 27.5 bike apart from the smaller original mountain bike or, the larger 29er bike.

    27.5 bikes come with optimized rear suspension and shorter chainstays and tube stems for easier and smoother manoeuvring on the trail.

    What Is a 27.5 Bike Used For?

    Mountain bikes are used by more adventurous riders that want to get off paved roads and onto trails in wooded areas, along rocky terrain, and other challenging landscapes.

    The 27.5 bike is a specialised mountain bike that straddles the line between the need for speed and manoeuvrability. A 27.5 bike is favoured by many of today’s best and more decorated MTB competitors.

    A 27.5 bike can ride faster than standard 26-inch mountain bikes since the wheels are larger. At the same time, it is smaller than a 29er, therefore easier to accelerate and control.

    The 27.5 bike is an ideal bicycle for both recreational riders and competitive racers, depending on the MTB discipline (I’ll cover these a bit later) and your personal strengths and preferences.

    History of the 27.5 Bike?

    Generally seen as a compromise between the standard 26-inch mountain bike and the 29er, the 27.5 bike was introduced to the public by famed bicycle designer Kirk Pacenti in 2007.

    Pacenti was looking for a way to combine the benefits and features of both available mountain bike sizes into a mid-sized bike to create a mountain bike that split the difference between handling control and speed.

    The new design succeeded in offering mountain bike enthusiasts a third choice when heading to the trails.

    27.5 mountain bike being ridden on a mountain bike trail

    The 27.5 bike started to catch on during the 2010 biking season. Nino Shurter put the 27.5 bike on the competitive bike racing map in 2012 when he won a World Cup in South Africa[2] and won a silver medal in the Olympics in London.

    After Shurter’s successes, manufacturers began to develop more 27.5 bike options, and most major mountain bike brands now offer 27.5 bikes that are used by recreational bikers and professionals alike.

    How Has the 27.5 Bike Progressed Over the Years?

    The design and manufacturing of the 27.5 bike has not changed much since it came on the market over a decade ago. Although, Pacenti and others in the industry continue to look for ways to improve the performance of the 27.5 and other mountain bikes.

    Engineers and designers will continue to work on improving the performance and look of 27.5 mountain bikes. Still, you can expect the 27.5 bike to remain essentially the same design, style, with marginally performance increases for years to come. 

    27.5 vs 29er Mountain Bikes - Which is Better?

    So as you’ve probably picked up on by now, 29er bikes are mountain bikes with even larger wheels. 

    What benefits do 29er bikes provide vs 27.5 MTBs? The table below encompasses a few of the main differences between these two increasingly popular bike choices. 

    27.5 MTBs 29er MTBs
    Faster acceleration Better for enduro & XC races
    Better for bike park riders Larger tyre size provides increased traction
    More suited for flow trails than technical trails Better on technical trails with rock gardens
    Better handling and control Better suited to tall riders
    Less suitable for long intense races Good for downhill riders who want to go fast
    More suited for shorter riders Faster top speed
    Lighter and more manoeuvrable Increased attack angle for crossing large obstacles

    Who Should use a 27.5 Bike?

    Mountain bikes with 27.5-inch wheels are typically used for bikers who are willing to sacrifice their top speed for agility and flexibility on the trail.

    The size and design of 27.5 bikes allow you to change direction and accelerate off the mark easier, making it ideal for a more casual ride or a competitive trail with many twists, turns, and variations in the landscape.

    Whether you are a competitive bike racer or an outdoor enthusiast with a penchant for challenging mountain bike trails, a 27.5 bike is an off-road bicycle that handles well in the rocky terrain.

    However, a 29er might be a better option if you constantly ride courses with big rock gardens as they benefit from a better attack angle. 

    A 27.5 bike can also double as reliable urban transportation that can manoeuvre through traffic smoothly.

    Who Shouldn't use a 27.5 Bike?

    27.5 inch mountain bike riding on rocky trail

    A 29er is typically preferred over a 27.5 bike by those who have the need for speed. The “tweener” has a slower top speed than the 29er and will be hindered more by large objects on the trail.

    While 27.5 bikes can be used for road or street riding, they do not travel well and take up a lot of room in a home or office.

    Riders with limited experience should start off slowly before hopping on a 27.5 and heading onto an advanced mountain trail.

    There are plenty of less-dangerous paths and trails for novice mountain bike riders to learn how to manage rocky terrain without increasing the risk of injury by tackling a path for more experienced riders.

    What Competitions/Events are 27.5 Bikes Used In? 

    The 27.5 mountain bike is used at the highest levels of mountain biking competitions around the world, including the Olympics and the UCI World Champions.

    Some of the most notable wins are Miranda Miller and Loic Bruni who both won with 27.5 bikes at the UCI World Championship[3], and Nino Shurter and Jenny Rissveds who took home the Olympic Gold in 2012 and 2016, respectively.[4] 

    Benefits of 27.5 Bikes

    A 27.5 bike allows you to head deep into thickly wooded or rocky areas to explore challenging trails with stunning backdrops.

    The best way to describe the benefits of the 27.5 mountain bike is by comparing it to the traditional 26-inch and 29-inch bikes.

    All three are suitable for mountain bike activities with slight variations that may appeal to your size, experience, and preferred types of terrain.

    When looking at all three, the advantages a 27.5 bike has over the others include:

    27.5 Mountain Bike Benefits
    Faster than 26-inch bikes
    More flexible and agile than 29er bikes
    More forgiving than 26-inch bikes
    Larger wheels require less suspension
    Higher top speeds than 26-inch bikes
    Quicker acceleration than 29ers
    Better traction than 26-inch bikes
    Offers smaller riders a larger-wheeled bike that is more comfortable than a 29er

    As more professional mountain bike competitors choose 27.5 bikes, the benefits become increasingly pronounced. 

    Risks Associated with a 27.5 Bike

    Mountain bike riding comes with a certain set of inherent risks.

    A 27.5 bike is designed for use on rocky, sometimes treacherous terrain. Collisions and falls can lead to serious injury, especially with novice riders or those not wearing protective safety equipment.

    27.5" mtb rider jumping over a ramp
    27.5" MTBs are versatile, they're capable of riding downhill trails with big air as well as flatter technical trails

    The 27.5 bike is no more or less dangerous to ride than any other mountain bike, though it offers a bit less control when out on a trail than smaller bikes.

    You should always wear protective gear when mountain biking, regardless of the size of the bike. 

    Environmental Impact of Using a 27.5 Bike

    Using a 27.5 bike for your commute will have a positive impact on the environment, by avoiding the emissions that would be created by traveling by car or public transportation.

    The environmental impact of a 27.5 bike typically comes from when people try to mountain bike in areas that do not have maintained trails. This can cause erosion and has an effect on both the local landscape and wildlife in the area. 

    Does the 27.5 Bike Require Anything to Keep Functioning?

    A 27.5 bike requires relatively little regular maintenance to keep it running in top condition.

    Mountain bikes will take a certain amount of abuse, so it is important to make sure the various moving parts remain secure to ensure a smooth and safe ride.

    Pay attention to tyre pressure and wear, chain lubrication, and a regular inspection of bolts and other components should be enough to maintain a 27.5 bike, outside of needed repairs and adjustments from defects or accidents.

    You should take care to clean your bike, including the chain and components, after every ride if dirty or every other ride.

    What to Wear when Riding a 27.5 Bike

    What you wear when mountain biking should be based upon the terrain and weather that you're riding in. Don't forget your helmet!

    Mountain biking can be a rough ride in the great outdoors, so while there are no set rules regarding what to wear when hitting the trails on a 27.5 bike, there are some recommended items that will make your ride safer and more enjoyable.

    Weather can also play a factor when gearing up for a mountain ride. The following are among the various items you could or should wear when riding a 27.5 bike:

    • Full-face MTB helmet 
    • Padded shorts and shorts liners
    • Biking jersey
    • Weather-appropriate layered, insulated clothing
    • Pedal-compatible footwear
    • Spine protector & body armour
    • Gloves
    • Protective eyewear

    Always remember to wear protective gear when you are mountain biking! Helmets save lives.

    What Accessories are Recommended when Using a 27.5 Bike?

    There is no shortage of accessories designed to keep mountain bike riders as safe as possible and looking stylish in the process.

    From headgear to footwear, you can choose from a wide selection of equipment to use while riding a 27.5 bike.

    Among the accessories available for 27.5 bike riders include:

    • Emergency bike repair kit, including pump
    • Frame protection tape
    • GPS, tracking apps
    • Saddle bag, storage compartment
    • Hydration bladder
    • Puncture-proof tyres

    When choosing accessories to improve the performance, safety, and look of your mountain ride, check that your safety gear meets all recommended standards and guidelines.

    27.5 MTB FAQs

    650b is a size of bicycle wheel that is roughly 27.5 inches in diameter.

    650b and 27.5 are interchangeable terms which mean the same thing. 

    The recommended height for riders of a 27.5 bike is 165 – 183cm (5′ 5″ – 6′)

    If you’re shorter than 165cm (5′ 5″) you’ll be better off on a 26″ bike. If you’re taller than 183cm (6′) a 29″ MTB will be more suitable. 

    As always, your best bet is to test ride different bike sizes before deciding which is best. 

    Summary - What Is a 27.5 Bike?

    Hopefully you’ve found this article helpful. I tried to cram in as much detail as possible and you should now understand what a 27.5 MTB is and what they’re suitable for. 

    Of course, the best way for you to learn bout 27.5 MTBs is to go and ride one yourself. If you’re interested, head down to your local bike shop who should have several different options for you to test ride! 

    What is a 27.5" mountain bike?

    If I left any of your questions unanswered, leave me a comment below and ill get back to you asap. 

    As always when you’re heading out on your bike remember to take a good quality bike lock with you. Check out the recommendations down below for some high spec affordable locks.

    Lock it or lose it.

    Ciao for now!






    Author of This Post:
    Picture of James Grear (Lead Editor)
    James Grear (Lead Editor)

    Understanding how devastating it is to have a bike stolen, I've researched & immersed myself in the world of bicycle security since 2013.

    I then built BikeLockWiki in 2019 to share everything I'd learned with the worldwide cycling community so that cyclists can improve their bike security skills and make informed decisions when purchasing new products and services.

    Learn More about Me & BikeLockWiki here.

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