Bearings on a bicycle: everything you need to know |

Bicycles comprise many components and each requires regular servicing to keep things running smoothly. None are more crucial than the humble bearings. Often overlooked, almost every moving part of your bike operates on bearings and, if not cared for properly, can hinder your bike’s performance over time.

Let’s take a closer look at various bearings on a bicycle and how you can best care for them. Alternator Bearing

Bearings on a bicycle: everything you need to know |

A bearing  on a bicycle facilitates movement when two materials are in contact. Though not something we may always consider, there are many moving parts on a bicycle. The headset allows your handlebars and front wheel to move, the bottom bracket allows your cranks to turn for you to pedal and the wheel bearings allow them to spin freely. 

There are two common types of bearings: loose bearings and sealed bearings. Loose bearings comprise loose ball bearings, which sit inside either a metal cage or flush against a metal race. They are packed with grease to reduce friction, helping them move easily and reduce wear. Loose bearings were the standard in traditional bike building and they are still used today. 

Sealed bearings are an evolution of the loose bearing concept. Rather than the bearings making direct contact with a component, sealed bearings operate within their own unit, confining the wear inside the bearing itself. The ball bearings are surrounded by an inner and outer race and an inner and outer seal. 

As bearings have developed, new materials have been introduced, focusing on performance and longevity. As with traditional loose bearings, stainless steel ball bearings are still the standard today. This is the default material unless otherwise stated.

In more recent years, ceramic bearings have been introduced into pro-cycling and have trickled down to general retail. There are two main types: hybrid ceramic and full ceramic. The former houses ceramic ball bearings in a steel cage, and the latter, both parts are ceramic. The theory is that ceramic bearings can be made almost perfectly spherical, reducing friction, requiring less maintenance, and are harder so they last longer. There is much debate about whether the steel cage in a hybrid bearing severely impacts this claim and whether ceramic bearings are worth it?  The main point is that there are different materials to suit different needs and it is best to research or ask for advice if you are thinking of upgrading your sealed bearings.  

Material aside, sealed bearings offer significant benefits compared to their traditional counterparts.

With use, bearings will eventually begin to feel rough. This is either due to the ball bearings themselves becoming misshapen or because the surface they make contact with has become ‘pitted’. ‘Pitting’ is where the ball bearing has worn away or left indentations on the surface, and the contact point is no longer smooth. In loose ball bearings, this surface is typically a direct part of the component, i.e. hub internals, a bottom bracket spindle, headset cup etc. As stated above, sealed bearings contain this within the bearing itself.

When loose bearing surfaces become pitted, changing the bearings will have little impact on the overall performance and is unlikely to help the component run much smoother. With sealed bearings, replacing the whole bearing includes both bearing and surface alike, leaving that part running like new. Furthermore, the seal helps protect the ball bearings from the elements and keeps the grease in for longer.

It is key to note that components will contain either loose or sealed bearings when new and will not be cross-compatible with the other. Knowing which type of bearing you are looking for can help you make an informed decision when changing or upgrading components, particularly on larger ticket items such as wheels.  

Though designed to be long-lasting and more durable, sealed bearings don't last forever and still need servicing and regular check-ups. If you leave things too late the damage can extend beyond the bearing itself and ruin your frame. Worn-out hub bearings can damage the wheel’s axle, bottom bracket bearings can damage the spindle, and headset bearings can damage the steerer tube.

When left unserviced, worn-out sealed bearings can be difficult to remove as corrosion sets in over time, especially if the bike has not been cleaned and dried after a ride. 

To keep your bearings healthy and replace them when needed, look out for the following signs:

If you notice any of these around your bearings, get your bike in for a check-up at your local bike shop - the sooner, the better!

Overall, the technology of bearings has come on in leaps and bounds in recent years, with sealed bearings offering a cost-effective alternative to traditional loose bearings. As the bearings can be replaced when worn, rather than the whole component, they are a great contribution to the “repair-don’t-replace” movement and are designed to keep working smoother for longer.

Tech Editor here at Liam can also be found photographing bikes as well as revelling in cycling's intricacies. Whether it's gravel, mountain, or e-MTB as long as it's a bike on dirt, he's happy. Editorial and general enquiries: Advertising and commercial:

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Bearings on a bicycle: everything you need to know |

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