When you think of expensive and exotic mountain bike components and frame choices, they’re mostly made from carbon fibre, right? Rims, handlebars, and even bottle cages can be made from the coveted material, delivering those two attributes that mountain bikers value most: strength and lightness.
But there is another material that starts with ‘c’, also promising much-vaunted benefits for your ride: ceramic. Hidden in the bearings on a bicycle and cartridges of many pro mountain bike hubs, bottom brackets and pulley wheels are ceramic bearings. They spin easier, with less effort, enhancing efficiency and delivering those incremental gains that matter during a long endurance ride.
Some of mountain biking’s most expensive wheelsets are built with ceramic bearings spinning their hubs. But you’ll find ceramic bearing upgrades available for your bike's crucial rotating components, like its bottom bracket and pulley wheels. But why are ceramic bearings considered superior to steel? And do they offer benefits that justify their significant cost?
Why do riders choose ceramic bearings for mountain bikes?
Bearings live a challenging component life in any off-road bike, especially if you are riding in the UK, or notoriously muddy regions of Europe or North America.
Suppose you are a committed all-weather rider, invested in severe weather gear, allowing you to ride all year. In that case, your mountain or gravel bike’s wheel hub and bottom bracket bearings will be exposed to a lot of potential mud contact and moisture ingress. Even the slightest trace of dirt or grime inside a bearing assembly starts becoming a grinding agent – ruining the perfectly spherical shape of your bearings and shortening their lifecycle.
Grime as a grinding agent is one issue, but moisture ingress is the other, triggering rust with traditional steel bearings. Ceramic bearings don’t corrode and rust, as steel bearings do when moisture seeps into your bottom bracket, hubs or headset. For mountain bikers seeking true ‘fit-and-forget’ components that contain bearings, the appeal of ceramic’s corrosion resistance is obvious.
Ceramic bearings spin better
The theoretical long-term maintenance benefits of ceramic bearings are appealing but for many riders, ceramic bearing upgrades to their bottom bracket, hubs or drivetrain pulleys are performance-related.
CeramicPivotBearing.jpg, by CeramicSpeed
Ceramic bearings are nearly a third harder than steel. That means greater force can be applied during manufacturing, creating a more perfectly spherical shape with smaller tolerances. Because ceramic bearings are much harder than steel and more perfectly round, there’s a lower probability of misalignment and friction losses over time.
But does a tiny reduction in friction matter when you pedal a mountain bike across uneven and textured terrain, where smooth cadence and power transfer aren’t possible, as it would be on a track bike, riding at a velodrome?
The rotational speed counterargument
As with all deeply technical features in off-road cycling, like aero or carbon strength, there’s a lot of laboratory and test data supporting specifics of the ceramic bearing efficiency argument. In isolation, ceramic bearings do spin with less friction than steel – the difference is undeniable. But whether it makes an actual difference at mountain biking speeds, is debatable.
Ceramic bearing upgrades are very expensive. Although they can save a few watts, in theory, most mountain bikers will never spin the cranks with enough revolutions per minute to benefit from the friction reduction. It would help if you spun dizzyingly high revolutions to benefit from ceramic bearings and their lower coefficient of friction, but rider biomechanics are too mild.
A real-world example is comparing how ceramic bearings are used for industrial applications, where the friction reduction benefits are unlocked by machinery spinning at 20 000rpm. That’s a lot more than a 300rpm climbing cadence that riders might spin, when grinding along in 12th gear, on a 52t cassette.
For time trial road riders, the tiny friction reduction benefits that accumulate and compound on a slick TT bike built with ceramic hubs, bottom bracket, and drivetrain pulley wheels might make a tiny difference. But you’ll never notice the difference when grinding a mountain bike up that rocky Highlands climb.
The truth is that mountain bike cranks will never spin near the required cadence, to warrant a performance differential between ceramic and steel bearings for the argument of relatable riding efficiency. If they’re not going to save you that many watts during a mountain bike ride, why would you invest in ceramic bearings for your off-road bike?
Exotic but durable
Ceramic bearings might be expensive, but they can potentially outlast any steel equivalent by a multiple of ten, making them much closer to lifetime rotational components than steel.
Bottom bracket, hub, and headset bearings get worn out, and replacing them is costly if you ride often in muddy conditions. Durability is where the true value presents, with ceramic bearings – not marginal low-friction performance gains.
Mountain bikes stress their bearings a lot more severely than road bikes. You’re standing on the pedals during a technical descent, which places a lot of leverage load on the bottom bracket bearings – something road riders never do. It’s the same with headset bearings. On a mountain bike, when you ping through a rock garden or awkwardly land a jump, the headset can experience a spike in load stress, especially with longer travel 140mm+ forks.
Beyond the forces that technical mountain biking terrain works applies to your bottom bracket or headset bearings, environmental contamination is a real thing. Ceramic bearings will last longer if you ride hard all year, and don’t shy away from technical trail features like drops, jumps and rock gardens, which load your bike with impact forces.
Where to spend your ceramic bearing money
Committed mountain bikers who don’t stay home on the worst days of winter can benefit from the durability and longevity of ceramic bearings. They might be expensive as an initial purchase, but there’s real value in the investment because they will outlast steel bearings by many seasons.
If you’re on a budget, where should you prioritize spending money to upgrade from steel to ceramic bearings on your mountain or gravel bike? Those oversized ceramic bearing drivetrain pulleys might look cool, but most riders would get a lot more value by fitting ceramic bearings to the bottom bracket, where moisture and dirt ingress are real issues – and rider-applied loads are significant.
2022 privateer 141 FL rocker bearing.jpg, by Liam Mercer
When you divide your budget into smart spending, the priority hierarchy should be ceramic bottom bracket bearings first, headset bearings, followed by hubs, with drivetrain bearings last.
Pivot bearings? That depends on your dual-suspension mountain bike’s linkage design. Some linkages are more exposed to side loads and environmental contamination, while pivot bearing sizes also differ, with larger pivot bearings being much more resistant to wear. German mountain bike brand, RAAW, proves the concept of oversized main pivot bearings being superior with its Madonna enduro frame. If pivot bearing wear is a concern, selecting a frame with oversized bearings will make more of a difference than the choice of bearing material.
And for those riders who can afford to upgrade everything they wish from steel to ceramic, what is the most indulgent component? There’s no arguing with the slick feel of a dropper seatpost remote featuring ceramic bearings.
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