Thru-axles are the modern axle interface, but they come in varying widthsJosh Patterson / Immediate Media
Over the past five years, axles have transitioned from decades-old quick-releases to thru-axles, which offer a stiffer, more secure interface. There are several thru-axle standards to be aware of.
The 100x15mm front and 142x12mm rear thru-axles were common a few years ago, but the desire to increase wheel stiffness has led manufacturers to move to the wider ‘Boost’ axle spacing, which uses a 110x15mm front axle with a 148x12mm rear thru-axle.
If you’re buying a high-end mountain bike these days, nearly all of them will feature the Boost axle spacing. There are notable exceptions, however, such as the ‘Super Boost’ spacing found on the Pivot Switchblade, or the many very wide thru-axle standards used on fat bikes.
Before purchasing a new wheelset, make sure it uses the same axle type and width as your frame.
Carbon or alloy rims?
Carbon is still more expensive than aluminum, but it’s getting more affordable each yearJosh Patterson / Immediate Media
Increasingly, high-end wheelsets are built around carbon fiber rims. Compared to aluminum, carbon rims can be as stiff or stiffer, at a lower weight. That’s not to say you should completely write-off aluminum rims.
If you’re not concerned with ultimate weight savings or ultimate stiffness, but are looking to upgrade to a higher performance wheelset with an affordable price, then there are many quality aluminum wheelsets to choose from.
Mountain bike rim width is much wider than it was a few years ago. TIres are available in a wider range of sizes as wellJosh Patterson / Immediate Media
Rim width has increased for both road and mountain bikes. The critical dimension to keep in mind is the internal width. This distance determines the shape of your tires. For a given tire, a wider rim will increase tire volume and give the tire a flatter, squared-off profile. A narrower rim will decrease tire volume and give the tire a rounder profile.
Wider rims can also increase tire stability, which can make your bike feel more predictable through corners. At the same time, tires are designed with specific rim widths in mind. Going too wide can cause the knobs on the sides of a tire to sit too high, resulting in less grip through turns.
Pairing rim and tire width is a key consideration – especially with so many tire widths to choose from. Here are some rough guidelines to get you started:
2-2.25in tires = 23-25mm rim widths
2.25-2.4in tires = 25-30mm rim widths
2.4-2.6in tires = 30-35mm rim widths
2.6-3in tires = 35-40mm rim widths
If you have a favorite tire width and tread pattern, keep in mind which rim width you want to pair it with when buying a new wheelset.
Tubeless or tubes?
Whether you’re a traditionalist who prefers tubes or embrace tubeless tech, nearly all modern wheelsets are tubeless-compatibleJosh Patterson / Immediate Media
The debate over whether to run inner tubes or to rely on a tire containing only sealant boils down to personal preference.
Inner tubes are affordable and easy to replace without much fuss (or mess), but they’re also prone to punctures and generally require the rider to run higher pressures.
Tubeless systems are lighter, have been proven to roll faster and have the added benefit of self-sealing small punctures. Tubeless tires are more expensive and if you do get a flat, you’ll have to deal with a bit of a mess.
However you choose to roll, nearly all modern mountain bike wheelsets are tubeless-compatible.
More pawls and more teeth on a drive ring will increase freehub engagementJosh Patterson / Immediate Media
One often overlooked wheel feature is how fast the freehub engages. This speed is actually a measure of the distance your crank travels before the pawls inside the freehub engage the teeth of the drive ring to propel you forward. It is most often discussed in terms of ‘points of engagement’ or ‘degrees of engagement’. More points will result in fewer degrees and a faster freehub.
You can figure out the degrees of engagement by dividing the points of engagement by 360. For example: a DT-Swiss hub with 36 points of engagement will have 10 degrees of engagement. An Industry Nine hub with 120 points of engagement will have three degrees of engagement.
The differences in engagement speed is noticeable on the trail. In general, a faster freehub is better. A hub with a high number of points of engagement will allow you to get back up to speed quickly after coasting with less lag. It can make it easier to ‘ratchet’ up technical climbs – a technique where the rider takes a half or quarter pedal stroke in situations where there might not be enough time, or pedal clearance, for a complete stroke.
Engagement can also be a matter of diminishing returns once you reach a certain point. Additionally, the tighter tolerances of fast-engaging freehubs can require more maintenance as they’re less tolerant of contamination. They also tend to be louder and can have more drag.
Beyond the wheels, you should be mindful of what type of rider you are when shopping for a new set of hoops. If you’re a heavier or more aggressive rider, you should shy away from lightweight wheels and look for a sturdy set with a higher spoke count – most likely 32 spokes laced in the three-cross pattern.
If you’re a lightweight rider or if you use a lot of finesse on the trail, you can probably get away with running a lighter weight wheelset.
Above all, keep in mind the wheels’ intended use. If you’re riding technical trails, jumping off obstacles or racing enduro, an ultra-light XC wheelset won’t hold up to this sort of repeated abuse.
On the flipside, if you’re going to race cross-country, a wheelset designed for enduro racing is a bad choice. Not only will it add weight, the stiff, overbuilt rims can cause your frame to feel flexy.
Best mountain bike wheelsets
DT Swiss XM 1501 Spline One Boost 35
4.5 out of 5 star rating
The DT Swiss XM 1501 Spline One Boost 35 wheelsetMick Kirkman / Immediate Media
Best for: 27.5+ and 29+ riders in need of a durable wheelset
The DT Swiss Spline Boost 35 wheelset has an internal width of 35mm and is intended to be paired with 2.6-3 inch tires.
This alloy wheelset is available in 27.5 and 29 inch versions and features the proven DT Swiss Star Ratchet freehub. It’s an upgrade for overweight plus bike wheelsets that feels accurate and responsive on singletrack.
We hammered e*thirteen’s TRS Race Carbon wheels for a long while and they’ve proven an impressively durable and versatile performance upgrade.
The hooked carbon rims have an internal width 27mm. The large diameter hub flanges mean shorter, wider angled spokes for precise and surefooted cornering and tracking feel. The six-degree of engagement gives relatively quick power transfer through the fat hubs and short spokes that makes the wheels pop and accelerate.
The TR33 is NOBL’s Jack-of-all-trades wheelset. The carbon rims have an internal width of 27mm. NOBL’s carbon rims feature hookless profiles to increase durability and external nipples for easy truing. They come with tubeless tape pre-installed and have bead lips on the sides of the drop channel to make tubeless inflation easy.
The company hand builds its wheelsets using Sapim spokes laced three-cross to your choice of Hope, Industry Nine or NOBL-branded hubs manufactured by Onyx Racing. We tested the version with the Onyx hubset.
Onyx freehubs use a sprag clutch, which offers instantaneous engagement with no noise and very little drag. It does add a bit of a weight penalty, however.
Though somewhat narrow at 25mm internally, Knight Composites’ Trail wheelset strikes a good balance of lateral stiffness with just enough vertical compliance to keep them from being jarring. Changing directions and twisting the bike around corners with these happens with a quickness usually reserved for more rigid-feeling wheels.
The Project 321 hubs feature magnets (instead of the typical springs) to engage the pawls inside the rear hub for less drag. Pick-up is impressively quick, with just 1.66-degrees of engagement.
These wheels will pair well with the new type of more aggressive XC bikes that are more than ready for all-day trail ripping.
The ‘R’ in the name of this new Race Face wheelset stands for rally, implying this is a set of hoops intended to be ridden hard.
Race Face offers the Turbine R wheelset in 27.5 and 29 inch versions for standard and Boost axle spacing. The alloy rims have an internal width of 30mm, which works well with most aggressive trail bike tires in the 2.25 to 2.5 ichn-width range. The wheelset spins on the Race FaceVault freehub, which provides a speedy three degrees of engagement.
The Turbine R wheelset checks off all the boxes for a modern high-end alloy wheelset.
While many plus bike wheelsets have internal rim widths in the range of 35-40mm, the Industry Nine BC 450 pushes things out to 45mm. This extra wide stance works best with full, 3 inch-wide plus bike treads.
The BC450 is available in both 27.5+ and 29+ versions.
Many riders gravitate toward plus bikes for their flotation and superior traction. A freehub with rapid engagement can help you make the most of this traction by helping you navigate technical climbs.
This is where Industry Nine’s tried and true freehub system comes into play. It features six pawls engaging a 120-point drive ring, which results in a very speedy three degrees of engagement.