If you’ve visited our blog before and explored our content, you’ll know that bearings serve to reduce friction and allow for smooth, effortless, efficient and reliable rotation. This cuts down on energy consumption and improves performance for any number of components. This alone is the single most important function of bearings, however, there are so many different types. Bearing design is a very complex science. In this post, I’ll give you an overview of the bearings used in everyday devices and explain how to identify them.

What are bearings?

Bearings come in two types: ball bearings and roller bearings. The former is made from small metal balls arrays, held apart by a cage, which allows for free rotation around the bearing’s central axle. Roller bearings, on the other hand, have cylindrical outer races or “rollers” over which round inner rings rotate with relative freedom inside both races/rings. This type is much less common than its counterpart because it has more friction due to steel-on-steel contact as well as higher manufacturing costs. Other components such as gears can even contain both bearing types.

What are they used for?

Most commonly, bearings allow for rotation of a part around an axis and/or provide support to something so it doesn’t fall over: wheels on your car/bike, the axles of your pedals, cranks, etc; steering knuckles on your suspension fork; one or two sealed cartridge bearings in most hubs; hub “bodies” containing additional ball bearings that take up play between races (imagine a dust cap glued into the end of a hub shell); even suspension pivots like those atop Specialized’s Roubaix road-going full carbon forks contain ball bearings. You’ll also find bearings inside things like drawer slides and many children’s toys.

When should you replace them?

The ball bearings inside your hubs are there specifically so you don’t have to think about them. As long as they’re rolling smoothly, they’ll probably last the life of your wheels or at least many thousands of miles with proper maintenance. The same goes for cables and housing  – if these moving parts are working properly, leave them alone! If your headset is loose or your brakes feel sticky, that’s a good time to replace cables and housing  (and possibly also headset cups and bearings). With suspension forks, it’s usually pretty obvious when something needs replacing – most contemporary suspension fork designs are fairly resilient but if you’ve crashed yours several times without servicing it afterwards (or it has become heavily rusted), best get it serviced by a pro. That’s pretty much all there is to it really.

And last but not least, where should you buy them? Can you buy bearings online and will they be of good quality? Absolutely, so long as you choose a proven, established and professional supplier. Be sure to read reviews and ask questions to ensure you’re investing in a top-quality product.