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When buying a bike, one of the main considerations is wheel size and tire choice. It can be confusing! So let us guide you through some of the terminology and the pros and cons of different wheel and tire sizes and options.

When you go to buy a bike you are confronted with 3 choices when it comes to wheel size and it can be confusing as to which one is better for you. The wheel size refers to the diameter of the wheel. 

26-inch wheels used to be the industry standard but nowadays are less commonly found. You will find most bike brands and models offer a choice of either 27.5 or 29.

27.5 is sometimes known as 650B.

29 or what most industry people refer to as a 29er or just simply a “9ER”.

Plus Size – you will find this term pop up often and it refers to the tire width. A standard bike in either 27.5 or 29 will often have a tire width of 1.9 inches to 2.4 inches, depending on the purpose of the bike. Nowadays you can also get bikes with Plus size, which means the frame and fork width, as well as the rim of the wheel, are designed to accommodate Plus Sizes tires which are from 2.8 to 3 inches. This gives the rider more traction and stability and allows for a lower tire PSI (Tire Pressure). These tires are good in snow, sandy, or muddy conditions. Not recommended for racing or XC Type bikes.

Generally speaking the lower PSI you can run the more traction you will have, as the lower PSI means the tread(Grip) contact to the ground is wider.

Can wheels be interchanged? Generally on older model bikes no. Some bikes nowadays, for example, Giant’s Fathom are built to take either a 29er wheel or a Plus-sized 27.5 giving you some flexibility. But normally the bike frame and forks are built around the wheel size. You will often find models of bikes like Trance, Talon, or Anthem with model options for the different wheel sizes, where the bike components will be the same but the wheel size will vary.

The Mullet is a new development where people ride with a 29er on the front and 27.5 on the back. You mostly will not find this style on factory-produced common market bikes. You would need to custom order or customize yourself.

Here are some of the Pros and Cons of the different wheel sizes

26″ Wheels –

26″ Advantages

• Tend to weigh less than 27.5″ & 29er bikes, as their smaller wheels and forks save weight

• Smaller wheels are often better for technical terrain that requires fast reaction time, such as quick twitchy trails

• Fits all size riders very well; whereas larger bikes such as 29ers are often difficult for smaller riders to fit onto

• Quick off the line acceleration

• Increased lateral strength for riders who require high travel DH / FR bikes

26″ Disadvantages

• Less forgiving while going over bumps, roots, rocks, etc….

• Slower top-end speed than bikes with larger wheels

• Small wheels require added suspension to soak up terrain.  This can lead to decreased efficiency in the suspension by adding pedal bob to the bike

• Smaller tire footprint than bikes with larger wheels often means less traction

• Requires a higher tire pressure than larger wheels

27.5 Inch Wheels (650B)

27.5″ Advantages

• Provides a higher top speed than 26″ bikes while having faster quick reaction times than 29er bikes.  This is the main advantage of a 27.5″ bike, as its goal is to utilize the advantages of both 26″ & 29er bikes

• More forgiving than 26″ bikes

• Larger wheels mean less suspension needed, which increases overall bike efficiency

• Higher top speed when compared to 26″ bikes

• Good off the line acceleration than 29ers

• Better traction than a 26″ bike

• Good alternative for small riders who want a larger wheel bike, but don’t fit comfortably onto a 29er

27.5″ Disadvantages

• While more forgiving than 26″ bikes, these bikes are still less forgiving than 29er’s

• Slower top speed when compared to 29ers, even though they’re faster than 26″ bikes.

• Slower off the line acceleration when compared to 26″ bikes

• While having better traction than a 26″ bike, 29er’s still have better overall traction because of their large wheel size

29 Inch Wheels (29er)

29″ Advantages

• Provides better momentum and attack angle

• Extra grip, traction, and added balance

• A more comfortable ride and added Pinch Flat (Snake Bite) resistance

• Less tire wear

• More climbing stability

• Good for taller riders

• Offers more ground to crank clearance giving less chance of a pedal strike

29″ Disadvantages

•Heavier and weaker Wheels

• Slower Acceleration

• Requires more braking effort

• Can be cumbersome to turn tight corners

TIRES

Tire size is normally written on the sidewall of the tire and is written like this 27.5 x 2.35 as an example. The size always refers to inches and the first measurement given refers to the wheel diameter. Ie 2.75 will go to a 27.5 wheel only. The second measurement refers to the tire width…which means the width of the tread on the tire.

Some common tire widths are as follows:-

1.9 – City and cycle path riding

2.0, 2.1, 2,25 – XC riding and Racing

2.35 to 2.4 – All-mountain and trail (Enduro) riding.

2.6 – Normally used for full Downhill riding

The width and the tread pattern of the tire you best suited to you depends on riding conditions and terrain.

Tubeless or Tube?

The last thing you need to consider when it comes to wheels is whether to run tubeless or a tube.

Tubes you can carry and repair anytime, anywhere, just make sure you have the right size tube that matches your tire, a set of tire levers, and a pump.

But tubes are considered heavy and cumbersome, not only time-consuming to repair so the solution to that is Tubeless.

Tubeless is an advancement in mountain biking. It consists of a liquid placed inside the tire. You need to make sure the rim is secured with rim tape and both the rim and tire are tubeless-ready. The liquid acts as a sealant when the tire is punctured, hence keeping the tire inflated.

Nowadays a lot of mid to high-end bikes come “tubeless ready”, meaning they have the right tire and rim set up to run tubeless, you just need to add the liquid.

You can also buy tubeless repair kits/tire patch kits for this setup. When running tubeless you need to understand that you will have to top up your liquid inside the tire from time to time as it evaporates and becomes less effective.

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