What Wheel Size Should I Choose?

What wheelset is best matched to how you ride?
What wheelset is best matched to how you ride?

New wheels are an easy way to make your old bike feel new again. But, with so many different options out there these days, how do you choose the right wheel for you?

There are several important factors, from price to compatibility to warranty and rim material. Here’s a breakdown of different factors to think about when you head out shopping for new hoops.

What to consider when buying mountain bike wheels

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Wheel size

Are you still going strong on 26″ and don’t see a reason to change? Staying current with 29″? Somewhere in the middle with 27.5″? Or maybe one each of 27.5″ and 29″? Wheel size is largely determined by what frame you’re buying wheels for. But some newer frames do allow you to switch between 27.5″ and 29″. Others work with 27.5-plus or 29″ (or 26-plus and 27.5″). Not every wheel is available in every size, so this is the first place to start.

Rim width

After years of slow change, rim widths have started to vary widely in the last five or so years. If there’s one general trend, it is that rims have been getting wider across the board. Even cross country, traditionally the slowest to change, is starting to embrace internal rim widths up to 30 mm.

In the ever-growing range of rim widths available, the general rule is to pair the internal rim width (the distance between the inside of the two rim sidewalls) to what range of tire sized you want to run. Wider rims (29mm and up) are generally better for wider, more aggressive tires. Narrower rims (25-27mm) are generally better for narrower, faster tires. Increasing the rim width with tire diameter helps keep a consistent shape to the tire tread, so you’re getting all the benefits of the tread design. There is no hard and fast rules but most manufacturers will have a suggested range of tire diameters that work with each rim.

Weight vs. Strength

Light wheels accelerate faster, both from a stop and out of corners, and climb faster. Heavier wheels are, usually, stronger and more durable. Heavier wheels can also be less flexy, though with carbon fiber that is changing. One factor that hasn’t changed: lighter wheels are usually more expensive.

Trail feel and frame pairings

Once you get past standards and price, how the wheels actually feel when you put them on the bike is, obviously, the most important factor.

Different wheel designs intentionally aim for different weight-to-stiffness ratios. Added to this, more and more brands are trying to fine-tune vertical compliance while maintaining lateral stiffness. Why? An overly stiff wheel can be as bad as a wheel that’s too flexy, especially off-road. Feeling trail chatter from every pebble and root isn’t just uncomfortable, it adds fatigue over the course of a ride. But wheels still have to be strong enough to hold a line during hard cornering and through rough terrain. Depending on design priorities and intended use, different wheelsets strike differing balances between compliance and strength.

What is best depends on how you’re riding. XC wheels don’t need to be DH stiff, but there’s still a wide range between different XC wheels. If you prefer a comfortable ride, more compliant wheels are the way to go. If you never want to lose a watt of effort on climbs or in sprints, you might lean towards a stiffer wheel.

It also matters what bike you’re putting the wheels on. If your frame is already very stiff, adding a stiff wheel could make it uncomfortably rigid. On the other hand, if your frame has some flex designed into it a compliant wheelset could make it feel too soft and noodley. A stiffer wheelset could bring a flexy frame back to the ideal balance of precision, comfort and efficiency. The same is true for a compliant wheel on a stiff frame. There are no hard rules for matching wheels to frames, though. This all comes down to rider preference. The key is knowing what you want before you shell out for a fancy new set of carbon fibre, or aluminum, hoops.

Carbon fibre vs. aluminum

There is more to the choice between aluminum and carbon fibre than cost, though the latter has a reputation for astronomical prices. Aluminum rims aren’t just budget rims, either. There are several companies making incredibly high-quality metal rims.

So, what are the differences, then? Well, they feel different. Carbon fibre rims are often stiffer, though brands are starting to experiment with more compliant rims. Alloy rims are traditionally, and often still better at vibration damping. Carbon fibre does still tend to be lighter, versus aluminum. But they also fail differently. Aluminum rims usually dent before they brake while carbon fibre rims, when they do break, fail completely. Dented aluminum rims can often still be ridden, sometimes for months, while a cracked or broken carbon fibre rim is just broken.

What type of riding do you do?

As an example, Enduro bikes are great for descending at speed but might be overkill for trail riding.

It’s important to be clear early on which routes you plan to ride and what kind of terrain you want to ride the bike on.

This will help you decide which category of wheel you need.