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MTB wheel standards and how to choose one without fail.
Posted at: Mar 14, 2023
The following is an overview of MTB wheel standards, their compatibility, and how to choose the right wheel for you.
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Standards to check when buying MTB wheels
There are so many manufacturers, types, and standards of MTB wheels that it is difficult to understand. You may be wondering, “I want to upgrade, but which one should I choose?” and you may be wondering, “I want to upgrade, but which one should I choose?
However, when buying MTB wheels, there are actually only two parts to check: the rim and hub.
It is actually very easy to choose a wheel that matches your MTB’s compatibility standard.
MTB Wheel Rim Specifications
The rim, one of the component parts of the wheel, determines the corresponding tire. Since the width of the tire determines the distance to the frame, it will inevitably also need to match the frame.
| Standard | Main types | How to choose |
|---|---|---|
| Size(Inches) | 29 inches 27.5 inches 26 inches |
Basically, choose the same size as your MTB. However, in the case of disc brakes, it is possible to exchange to a lower size. |
| Inner rim width | 19〜30mm | The recommended tire size is determined for each rim, so choose the size you want to install. Rims with wider inner widths are required for larger tires. |
| Compatible tire type | Clincher Tubular Tubeless |
The rim standard determines the type of tire that can be mounted. |
| Brake type | Rim brakes Disc Brakes |
Rims for disc brakes cannot be used as rim brakes |
Most current MTBs are 29” (29er) or 27.5", but check the rim size on the official page of your MTB manufacturer to be sure. Alternatively, you can also check the tire size printed on the tires currently installed on your MTB.
In the past, 26-inch wheels were the norm for MTBs, so if you purchased a used 26-inch MTB, it is possible that some models may not be compatible with today’s fully assembled wheels.
Also, if you want to use tubeless wheels, which are now considered a must for MTB, you need to choose wheels with tubeless (or tubeless-ready) rims.
Hub Standards for MTB Wheels
The hub, the part that supports the rotation of the wheel, must strictly adhere to standards because it is the part that joins the frame and components.
In addition, while there are a great variety of hub standards, even one different standard can cause the hub to mismatch, making it the part that requires the most attention to standard compatibility when selecting MTB wheels.
| Standard | Main types | How to choose |
|---|---|---|
| Free body | Shimano HG Shimano Micro spline SRAM XD |
Choose the right sprockets for the sprockets you use. |
| Shaft type | Quick release(QR) Through axle(AX) |
Match frame and fork standards |
| Shaft thickness | 9mm, 12mm, 15mm | Match frame and fork standards |
| End width | 100mm, 110mm(front) 135mm, 142mm, 148mm(rear) |
Match frame and fork standards |
| Disc mounting | 6 bolts Center lock AFS |
Match the wheel standard |
There are so many things to check and so many types that it may seem confusing, but there are not that many patterns for MTB wheels sold on the market as complete sets. However, there are not that many patterns for complete MTB wheels on the market, and considering compatibility, which will be explained later, you will naturally narrow down your choices.
MTB wheel standards and compatibility, how to choose a wheel that will never fail you
When selecting wheels for MTB, it is fundamental to narrow down your search according to compatibility with the chassis.
Compatibility with the vehicle body should always be narrowed down in this order, as compatibility is strictly in the following order.
- brake
- frame/fork
- tires
Types of Brakes
The first important factor is the type of brake: V-brake wheels cannot be used with disc brakes, and vice versa. If you make a mistake here, the first thing to do is to make sure that they are compatible with the chassis.
In the past, V-brakes were the mainstream for MTB, but almost all current MTB brakes are disc brakes. Therefore, current MTB wheels are also almost exclusively disc brake wheels; if you want MTB wheels for V-brakes, consult a pro store.
In addition, disc brakes require a disc rotor to be mounted on the hub of the wheel, so the disc rotor compatibility standards must be matched.
The main rotor mounting standards are “Center Lock,” which is the current mainstream and advocated by Shimano, and “AFS” adopted by Campagnolo. Older models sometimes use the 6-bolt system, but this is not commonly used by major manufacturers today.
However, the disc rotor installation standard is not severe, since it is only “necessary to replace the rotor with an interchangeable one. However, when choosing 6-bolt MTB wheels, check to see if the brakes are compatible, as there are only a few types of rotors that are compatible.
Frame and Fork Compatibility
The most complicated and error-prone part of replacing MTB wheels is frame/fork compatibility. If they do not match, the wheel cannot be mounted on the frame and fork.
The following three types of frame and fork standards are generally available for MTBs in circulation: mounting type, shaft thickness, and end width.
| Mounting Type | End Width(F/R) | Shaft Diameter(F/R) |
|---|---|---|
| Through axle(Boost) | 110/148mm | 15mm/12mm |
| Through axle | 100/142mm | 15mm/12mm |
| Quick release | 100/135mm | 9mm/9mm |
Current top grade MTBs are boost standard (110 x 15mm/148mm x 12mm) through-axle. Many of the higher grade MTB wheels on the market are also manufactured with this boost standard.
Next is the 100mm front and 142mm rear thru-axle found on higher grade disc MTBs from a decade ago. This standard is similar to current disc road bikes, but the front wheel is 15mm, so it is a separate replacement for the road wheel as far as the front wheel is concerned.
Finally, the 100mm/135mm quick release standard is common in current entry MTBs. Although this standard is widely distributed as an entry MTB, there are extremely few types of replacement MTB wheels, and there are only a few upgrade options.
When upgrading MTB wheels to this standard, consider upgrading to a higher grade complete bike at the same time.
Tire Compatibility
Tires are relatively loose in MTB wheel compatibility. Tire compatibility is based on three things: size, thickness, and type.
When choosing MTB wheels, you basically decide on “how many inches” you want, which is good for tire size, but for thickness and type, the rim standard makes a big difference.
First, the type of rim determines whether it is tubeless, clincher, or tubular. It also determines the tires that can be mounted, which affects tire selection.
The appropriate tire size is “the inner width of the rim x 1.4 to 2.4 times the width of the rim,” but the manufacturer’s recommended tire size is determined for each rim, so that should be prioritized.
Compatibility with Components
Freebody compatibility is important for rear wheels with sprockets installed.
There are five types of free bodies as follows
- Shimano HG
- Shimano Micro Spline
- SRAM XD SRAM XDR
- Campagnolo
Of these, the Campagnolo type and SRAM XDR are freebodies for road use, so the three types are used in MTB wheels.
Since they are not interchangeable, you need to choose the freebody that matches your sprocket. However, some manufacturers have a system where only the freebody can be replaced.
How to find MTB wheels without making mistakes in terms of compatibility
Let’s take a look at how to actually look for MTB wheels in terms of compatibility.
Narrow down your search by brake standard.
The first thing to narrow down is the brake standard; in the case of MTB, even V-brake models may have a disc pedestal on the fork/frame, so take this opportunity to include whether you want to convert to discs.
Most MTB wheels currently in circulation are for disc brakes, so you will inevitably choose disc brakes, but when looking for wheels for V-brakes, do a search for “V-brake”.
If you are looking on a mail order site, you may not be able to narrow down your search by brake type, so use the search.
Narrow down your search by wheel size.
The next thing to narrow down is the wheel size.
As explained earlier, MTB wheels are available in 29-inch (29er), 27.5-inch, and 26-inch. Most bicycle shopping sites allow you to narrow down your search by size.
Basically, choose the size that is currently installed on your chassis, but with disc brake MTBs, “big can be small,” so it is possible to convert a 29er MTB to a 27.5 standard (or vice versa if clearance is available).
Compatibility with frame and fork
Next is the compatibility with the frame and fork. If you make a mistake here, you will not be able to install it on your vehicle, so be sure to make the right choice.
There are three types of frame/fork compatibility: through-axle boost, through-axle, and click-release, but it is difficult to find the right one because some mail-order sites do not have a filtering function.
If you want to do a search,
- mtb wheel 29er disc
- mtb wheel 27.5 boost
- MTB wheel 27.5 QR
MTB wheel + size + end standard” is a good way to search.
If you don’t find compatible wheels, consult a pro store!
There are quite a variety of MTB body standards, and it is tough for wheel manufacturers to accommodate all of these many standards, so many MTB wheels on the market are made to the standards of higher grade MTB complete bikes. Currently, the most common wheels are boost-standardized for disc brakes.
So, if your MTB is not boost-standard for disc brakes, your options for wheel upgrades are limited. However, a pro store may be able to suggest wheels that are not available on the Internet, so you should consult with them.
Also, although not all stores offer this service, some sports bicycle pro stores sell “hand-assembled wheels” where you can specify the rim, hub, spokes, and nipples, and they will assemble the wheels to your liking.
If you cannot find a wheel that fits your MTB, consult a pro store first.