How To: Fit a Wheelset to Your Bike

So you’ve settled on a Race Face wheelset and are nearly ready to buy, but you’re not sure how to make the right selection so it will fit your bike. Fear not – we’ve assembled this guide just for you.

What’s Your Wheel Size?

Modern mountain bike tires and wheels come in predominately 2 sizes: 27.5” and 29”.

There are two easy ways to check your wheel size.

1. Look at your old rim – it may have sizing written on it.
2. Look at your tire – it will have something like 29 x 2.40 written on it, or embossed in the rubber. 29 refers to your wheel diameter.
   1. Sometimes this sizing is shown in metric equivalents, so 29 x 2.40 could be displayed at 622 x 60.

• If your rim/tire says 29, or 622, you need a 29” wheel.
• If your rim/tire says 27.5 or 584, you need a 27.5" wheel.
• If your rim/tire says 26" or 559, we no longer offer this wheel size. 26” is an old mountain bike standard that has aged out of XC, Trail and Downhill bikes. If you’re looking for a 26-inch wheel, your best bet would be to go to your local shop for a rim replacement or look at other complete wheel options.

Front and rear wheels are often the same size, but not always. Ensure you check the size of each wheel.

Let’s Talk Axles

Thru Axles

These axles are the modern solution for securing wheels to mountain bike forks and frames. They go through the hub and screw into closed dropouts. Thru Axles are thicker, stiffer and more secure than QRs and have thus become the standard for our wheels and for mountain bikes in general.

Quick Release (QR)

Bike frames and forks used to engage with wheels using a thin 5mm quick release (QR) in slotted dropouts where Front and Rear hub axles rested. The QR would slide though the hub and clamp everything in place. These are not as secure nor as stiff as “thru axles” and are now typically only found on older bikes.

If you have an older bike with QRs and want to upgrade your bike, our wheels have tool-free swappable endcaps to convert a wheel built around a thru axle to a QR axle standard. Find Vault Hub Endcaps here.

Front Wheels

Once you know your front wheel size—27.5” or 29”—you’ll need to know your axle style, and your brake rotor mount type. Let’s focus on axles here.

The most common axle style for Race Face front wheels is 15x110 Boost. Here’s what those numbers mean.

Axle Diameter – the first number in your axle style. This is a measurement of your front axle diameter in millimetres. It’s usually printed on the axle, but you can also measure it using a set of calipers.

Hub Width – the second number relates to the width of your front hub in millimetres. Boost means that the width is larger than the previous hub width standard (100mm). This measurement is often printed on the axle but can alternatively be measured as the space between your drive side and non-drive side fork dropouts.

Exception – the difference between 20x110 and 20x110 Boost is the space between spoke flanges, and the position of the brake rotor interface. Check with your fork manufacturer to clarify whether you are running Boost or not.

Rear Wheels

Once you know your rear wheel size, you’ll need to identify your axle style, cassette body style, and brake mount type. Let’s start with axle style.

The most common axle style for Race Face rear wheels is 12x148 Boost. Rear axle styles are written in a similar fashion to front axle styles. The difference lies in how to best identify your axle’s style.

Axle Diameter – the first number in your axle style, measured in millimeters. It’s usually printed on the axle, but can also be measured using a set of calipers. Alternatively, check your frame manufacturer's website, or measure the diameter of the axle’s hole in your bike’s non-drive side frame dropout.

Hub Width – the second number relates to the width of your rear hub in millimetres. Boost means that the width is larger than the previous hub width standard of 142mm. Super Boost is even wider at 157mm. The best way to find this measurement is by checking your frame manufacturer’s website. It can also be measured as the space between your bike frame’s rear dropouts.

Cassette Bodies

With your wheel style understood, and your front or rear axle style understood, you’ll need to decide which cassette body you need for your rear wheel, and what brake mount type you need for both wheels.

Looking for a front wheel only? Skip straight to Brake Mount Style.

The cassette body is what matches your drivetrain’s cassette or “gears” to your rear wheel. There are three cassette body options in our wheel assortment: Microspline (MS), HG and XD.

Here’s how to select between those three for Shimano, SRAM and TRP cassettes.

Shimano and TRP: count the number of cogs (individual gears) on the rear cassette.

11 or less – select an HG cassette body.

12 – select a Microspline (MS) cassette body.

SRAM: count the number of cogs (individual gears) on the rear cassette.

9 or 10 – select an HG cassette body.

11 – select an XD cassette body (except model PG-1130 NX – HG).

12 – select an XD cassette body (except models PG-1230 NX and PG-1210 SX – HG).

Cassette bodies can be replaced with a different style if needed, allowing the rear wheel to accommodate multiple setups. But it’s best to get the correct complete wheel at the outset.

Brake Mount Style

Finally, you’ll need to know your brake mount style to purchase the best-fitting wheels for your rig.

There are two brake mount styles used on modern mountain bikes: 6-bolt and Center Lock (CL).