Upgrading your mountain bike wheels is one of the smartest investments you can make. A new wheelset doesn’t just change how your bike looks — it can completely transform the way it rides. From snappier acceleration and better climbing efficiency to improved cornering grip and durability on tough trails, the right set of wheels can take your riding to the next level.
But here’s the challenge: choosing a new set of wheels can feel like a bit of a minefield. With different hub spacing, wheel sizes, freehub bodies and more, it can get confusing trying to establish what you need.
That’s why we’ve put together this complete guide to mountain bike wheelsets. We’ll break down the terminology, explain what matters (and what doesn’t), and help you make an informed decision. Whether you’re upgrading your current bike or building a dream rig from scratch, this guide will give you the knowledge you need to choose the right wheels.
Table of Contents
- Wheel Size: 27.5″, 29″ or MX (Mullet)?
- Hub Spacing: Standard, Boost and Super Boost
- Freehubs: HG, XD and Microspline
- Brake Disc Compatibility
- Hub Engagement: Faster Pick-Up, Better Performance
- Aluminium vs Carbon Rims
- Intended Use: XC vs Trail/Enduro vs DH
- Weight: Is Lighter Always Better?
- Other Wheel Features Worth Considering
- Final Thoughts: How to Pick the Right Wheelset
1. MTB Wheel Size: 27.5”, 29”, or MX (Mullet)?
One of the first decisions to make is wheel size. Mountain bikes are generally designed around three options: 27.5”, 29”, or a mixed-wheel setup (MX/mullet). Each has distinct strengths:
- 27.5” (650b)
- Smaller diameter wheels.
- More agile and playful — great for technical trails, jumps, and manoeuvrability.
- Accelerates quickly but loses momentum faster than 29”.
- Still common on freeride and bike park bikes.
- 29”
- Larger diameter wheels.
- Roll over obstacles more smoothly and maintain momentum.
- Offer better traction and stability, especially at speed.
- Favoured by XC racers, as well as many trail/enduro riders.
- MX / Mullet (29” front, 27.5” rear)
- Best of both worlds: rollover and stability from the 29” front, agility and clearance from the 27.5” rear.
- Popular in downhill and enduro racing.
- Gives more rear wheel clearance on steep trails.
- Not all frames support this setup.
👉 What to choose?
- If you prioritise speed, stability, and efficiency go 29.
- If you like a playful ride and jibbing around go 27.5.
- If you want a mix of agility and rollover (and your frame allows it), try MX.
It’s also worth taking your height into account – many shorter riders prefer a 27.5” or MX set up (the larger wheel can buzz your backside on steeper sections, and a shorter rider may not feel as comfortable muscling a 29er through corners). Conversely, a taller rider may have a preference for a full 29er set up, benefiting from the speed and stability, while feeling less hindered while cornering due to having more leverage.
2. Hub Spacing: Standard, Boost, and Super Boost
Hub spacing refers to the width between the dropouts of your bike’s frame and fork. It dictates which wheels will physically fit your bike.
- Standard (non-Boost)
- 100mm front, 142mm rear.
- Found on older bikes. Becoming rare.
- Boost
- 110mm front, 148mm rear.
- Now the most common standard.
- Provides stronger, stiffer wheels by increasing the bracing angle of the spokes.
- Creates more tyre clearance.
- Super Boost
- 110mm front, 157mm rear.
- Seen on some downhill and enduro bikes.
- Offers maximum stiffness and strength, but less compatibility with frames and cranks.
👉 What to choose?
Always match your wheels to your bike’s hub spacing. Boost is the most common today. If you’re buying for a new build, Boost-compatible wheels are almost always the safe bet.
3. Freehubs: HG, XD, and Microspline
The freehub body is the part of the hub that your cassette attaches to. Not all drivetrains use the same type:
- HG (Hyperglide)
- The original Shimano design.
- Works with most Shimano 8–11 speed and some SRAM cassettes.
- Still widely used on budget and mid-range bikes.
- XD Driver (SRAM)
- Designed for SRAM 12-speed Eagle cassettes with a 10-tooth smallest cog.
- Allows for wider gear ranges.
- Not backward compatible with HG.
- Microspline (Shimano)
- Needed for Shimano 12-speed cassettes (like XT and XTR).
- Also supports 10-tooth small cogs.
- Not compatible with HG or XD.
👉 What to choose?
It depends on your drivetrain. If you have SRAM Eagle, you’ll need an XD driver. If you have Shimano 12-speed, you’ll need Microspline. Anything else likely uses HG.
4. Brake Disc Compatibility: Centre Lock vs 6-Bolt
When choosing a wheelset, it’s important to make sure your brake rotors will fit the hubs. There are two main mounting standards for mountain bike disc brakes: 6-bolt and Centre Lock.
6-Bolt
- The most common standard, especially on mountain bikes.
- Uses six small bolts to attach the rotor to the hub.
- Simple, reliable, and compatible with almost any brake setup.
- Easy to service with standard tools.
- Slightly heavier than Centre Lock because of the extra hardware.
Centre Lock (Shimano system)
- Uses a splined interface and a single lockring to secure the rotor.
- Faster and cleaner to install or remove.
- Typically a touch lighter and stiffer, giving a solid connection.
- Requires a specific lockring tool (similar to a cassette tool).
- Can be converted to 6-bolt using an adaptor, but not the other way around.
👉 What to choose?
- If you already have 6-bolt rotors, it’s easiest to stay with 6-bolt hubs.
- If you’re running Shimano brakes or prefer clean installation, Centre Lock is great.
- Both systems perform equally well in braking power; it’s mainly about compatibility and convenience.
👉 Pro tip:
Check the rotor size compatibility of your frame and fork, too. Most trail and enduro bikes can run 180–203mm rotors, while XC bikes often stick to 160–180mm. Larger rotors improve heat management and stopping power, which is crucial for heavier riders or long descents, but not all bikes can take them.
5. Hub Engagement: Faster Pick-Up, Better Performance
When you stop pedalling, your hub’s pawls disengage. When you pedal again, the hub needs to re-engage. The number of engagement points determines how quickly this happens.
- Low engagement (18–24 points)
- Slower pick-up. You’ll notice a lag when starting to pedal again.
- Fine for casual trail riding, but less precise for technical climbs.
- Medium engagement (36–54 points)
- A good balance between performance and durability.
- Found on many mid-range hubs.
- High engagement (90+ points)
- Near-instantaneous pick-up.
- Helps with technical climbing, ratcheting in rock gardens, and sprinting out of corners.
- Can increase wear on hub parts.
👉 What to choose?
If you ride techy terrain or race enduro/XC, faster engagement feels much better. For general trail riding, medium engagement is usually enough.
6. Aluminium vs Carbon Rims
The rim material has a huge effect on performance, weight, and price.
- Aluminium
- Affordable and widely available.
- Can dent under hard impacts, but often still rideable.
- Slightly heavier, but forgiving on rough terrain.
- Carbon
- Lighter and stiffer, which means sharper handling and faster acceleration.
- Can feel harsher on rocky terrain.
- More costly, and when they fail, they usually crack rather than dent.
- Many brands now offer lifetime warranty to ease this concern
👉 What to choose?
If you’re racing or want maximum performance, go for carbon. If you want value, durability, and peace of mind, then aluminium is a great option.
7. Rim Width: How It Changes Tyre Performance
The internal rim width affects how your tyre sits and rides.
- Narrow (20–25mm internal)
- Lighter.
- Creates a more rounded tyre profile.
- Common on XC bikes with narrower tyres (2.1–2.3”).
- Medium (28–30mm internal)
- The sweet spot for trail and enduro.
- Gives tyres more support at low pressures, increasing grip and stability.
- Works well with tyres in the 2.35–2.6” range.
- Wide (30mm+)
- Maximise tyre footprint for grip.
- Favoured in downhill and aggressive enduro setups.
- Adds weight and can make tyres feel “squared off” if not matched properly.
👉 What to choose?
- XC: 25–28mm.
- Trail/Enduro: 28–30mm.
- Downhill: 30mm+
8. Intended Use: XC vs Trail/Enduro vs DH
Wheels should match how and where you ride.
XC (Cross-Country)
- Prioritise light weight and climbing efficiency.
- Aluminium or carbon with narrower rims.
- Higher hub engagement provides immediate power transfer and precise control – particularly useful if racing
Trail/Enduro
- Balance of strength and weight.
- Wider rims (28–30mm) for support.
- Faster hub engagement is useful for technical sections, particularly technical climbs
- Aluminium or carbon depending on budget.
Downhill (DH)
- Strength and durability come first.
- Heavier, wider rims (30–35mm).
- High-engagement hubs are less important for DH but can be useful for quick bursts of acceleration, but pedal kickback can be more noticeable on longer travel bikes.
- Carbon wheels can offer increased performance (stiffer, lighter etc), but aluminium wheels are still commonly used for their lower cost and durability.
9. Weight: Are Lighter Wheels Always Better?
Not necessarily. While lighter wheels feel snappier when climbing and accelerating, strength and reliability often matter more.
- Light wheels – Great for XC and marathon racing.
- Mid-weight wheels – A balance for trail and enduro.
- Heavy wheels – Often stronger and more durable for bike park and DH use.
👉 Rule of thumb: Don’t sacrifice strength for grams unless you’re racing XC. A few extra grams are worth it if it means your wheels survive a season of hard riding.
10. Other MTB Wheel Features Worth Considering
- Tubeless compatibility – Almost all modern wheels are tubeless-ready, but double-check. Running tubeless reduces flats and allows lower pressures for better grip.
- Spoke count – 28–32 spokes is standard. More spokes generally mean stronger wheels, fewer spokes can mean lighter weight.
- Maintenance and support – Look for brands with good warranty and replacement part availability.
Frequently Asked Questions About Mountain Bike Wheels
How do I know which wheel size fits my bike?
Your frame and fork will determine which wheel size you can run. You’ll often find the size printed on your current tyres (e.g 27.5” or 29”). If in doubt, check your bike’s specification or pop into your local bike shop for help.
Are carbon mountain bike wheels worth it?
Carbon wheels are lighter and stiffer, so they offer improved acceleration and responsiveness. If you ride aggressively or race, carbon might be worth the upgrade. For everyday trail riding, alloy wheels remain a solid choice. In terms of weight and it’s impact on your speed/rolling resistance, your tyre choice is likely to have a bigger impact.
Can I use wider tyres on my rims?
Yes but within reason. Each rim will have an ideal tyre width range. Wider rims will work best with wider tyres (2.4”-2.6” for example), offering better grip and support. Always check your manufacturer’s guidelines if you’re unsure, to avoid poor fit and handling.
How long should a mountain bike wheelset last?
With proper care (keeping spokes tensioned, rims true and bearings serviced), a quality wheelset can last several years. Keeping up to date on your maintenance can help prevent costly replacements later.
How do I convert to tubeless?
You’ll need tubeless-ready rims, tyres, valves and sealant. In simplest terms, you need to remove your tubes, install the tubeless valves, add sealant and then inflate the tyre until it is seated on the rim. Add the sealant in at the bottom of the tyre and remember not to turn the wheel until the tyre is installed all the way round – it can get messy otherwise. We also offer tubeless set up in-store!
Should I upgrade my wheels or tyres first?
If your tyres are worn, or not suited to the terrain/conditions, then start here. Swapping your tyres is one of the cheapest and most effective performance boosts you can buy. Once you’ve found your tyres of choice, then consider upgrading your wheels to unlock the next level of ride quality and performance.
Final Thoughts: How to Pick the Right Mountain Bike Wheelset
Choosing a mountain bike wheelset doesn’t have to be overwhelming. Here’s a simple framework:
- Start with compatibility – wheel size, hub spacing, and freehub must match your bike.
- Decide on material – aluminium for value and toughness, carbon for light weight and precision.
- Match rim width and strength to your riding style – XC riders go narrower and lighter, enduro/DH riders go wider and stronger.
- Think about engagement and performance – faster hubs help technical riding but aren’t essential for everyone.
- Balance weight and durability – light wheels can make for a more nimble ride, but they also need to be suitable for your preferred riding style.
The perfect wheelset is the one that fits your bike, suits your riding style, and gives you confidence on the trail. Whether that’s a lightweight carbon XC set or a bombproof aluminium enduro pair, the right wheels will make your bike and your riding feel better than ever.
