Bicycle bearings: everything you need to know

The bits that keep your bike rolling

These often-overlooked components actually bring life to your bicycle. You can’t steer, roll, pedal or have a functioning drivetrain without bearings so let’s show them some love…


The different styles of bearings

Loose ball, loose ball in a retainer, needle, and cartridge are the main styles of bearing founds in cycling frames and components.

A ball-and-retainer system is similar to a loose-ball setup but makes for less expensive assembly, and are thus favorable on entry-level components
Thomas McDaniel / Immediate Media

Loose ball bearings

Loose ball bearings are the most traditional and require the use of bearings with a mated cup and cone. Although they’re the oldest, in many ways they can be superior. They are angular contact (more on this later) and offer excellent maintenance and performance characteristics.

The same can be said for loose ball in a retainer, but generally speaking this became popular in more cost-effective versions. In short, its attractiveness comes from the fact it’s quick and easy. Unfortunately, what makes it quick and painless — the retainer — also contributes to its average performance.

Needle bearings

Needle bearings (aka roller bearings) are becoming uncommon, except for in pedals, and even then they’ve lost a lot of ground to newer and cheaper tech.

They’re just like they sound — instead of ball bearings, they’re in the shape of a needle or cylinder.

They can create incredibly smooth rolling and stable platforms, especially under high loads, but in the cycling industry there’s a tendency to shy away from them due to the expense of creating good mating surfaces.

When not mated properly, they tend to fatigue quickly. Needle bearings often get replaced by multiple rows of cartridge bearings.

Cartridge bearings

Cartridge bearings have come to the forefront in recent years as a result of ever-increasing tolerances in hub, frame, and component bores.

Cartridge systems require precision to function well, and as technology trickles down, so does the frequency of their application.

The balls, cup and cone are contained in a cartridge that can be installed into a waiting bore. While having everything neatly packaged seems simple, the reality couldn’t be different, but the benefits seem to outweigh the skillset and tools required to maintain them.

The bearing diameters

Loose ball-bearing systems require a measurement of ball diameter, which is something like 3/16in (4.7625 mm).

There are other corresponding measurements required to overhaul balls and cone systems and your bike shop will be able to tell you more. More often than not, just replacing the balls is a great start (but bear in mind cup and cone dimensions can be challenging to find, depending on the brand and the age of the system).

As for cartridge, inside diameter (ID), outside diameter (OD) and width all contribute to bearing size, which directly correlates to bearing life. The measurements take the form of ‘15x24x5mm’ or similar. They often have a corresponding universal identifier, which in the case of the aforementioned bearing, would be 6802, for instance.

Cartridge-style bearing have an outside diameter (OD), inside diameter (ID) and width measurements, and sometimes have universal identifiers such as ‘61902’
Thomas McDaniel / Immediate Media

With calipers you can measure a cartridge, enabling you to find a replacement quite easily.

Headsets pose a unique characteristic in that they have angled races. Their sizing might read more like ‘46.9 x 7 x 45°’ to identify the OD, width and angular measurements of the bearing race, respectively.

With regards to performance, the bigger the ball, the better, as increasing diameter has an exponential factor for increasing contact. More contact means more even distribution of forces, and results in better rolling performance and durability.

Several major wheel manufacturers have pushed towards larger bearings in recent years and there are ever-increasing hub dimensions to show.

Most high-performance brands have pursued increased spacing (from left to right), in terms of width. Both ball diameter and spacing can contribute to better performance and longevity, especially in wheels and bottom brackets.

Radial vs angular cartridge

Two types of cartridge bearings have become popular: radial and angular contact.

Radial are the most common as they are cheaper. They attempt to carry the load in a truly radial direction, which is vertical in terms of hubs, cranks, suspension pivots or derailleur pulleys.

Subsequently, they sacrifice a small amount of performance because forces within the moving parts usually have a non-radial vector associated. As a result, they have to compensate with decreased tolerances.

In short, there’s less precision associated with radial cartridge systems. As such, they don’t have any directional application — there is no inside or outside.

As a benefit, because they are slightly less tolerance-dependent, they can be used in applications that aren’t quite as expensive.

A few examples of cartridge bearing systems — an angled headset on the left and a tiny front hub bearing in the middle and on the right
Thomas McDaniel / Immediate Media

Conversely, angular contact bearings require tight tolerances because they are directional. There is an inside and outside component and they can be compared to the old-style cup-and-cone systems in terms of design.

They complement the radial and side-force loads exerted with the rotating components of a bike, but require extreme tolerances in mating bores to accomplish a precise fit and rolling performance.

For the most part, angular contact is the most appropriate application for hubs, cranks and suspension. However, many hubs and frames don’t posses the mating bore to complement the precision of the angular cartridge.

This precision is where brands such as Industry 9, Chris King, White Industries, Phil Wood and Alchemy Wheel Works get their reputation.

Measuring quality

Interestingly, in my quest to research bearings, I learned the only quality standard associated with bearings is far from robust. ABEC Ratings (Annual Bearing Engineers Committee – 1, 3, 5, 7, and 9) were meant to provide a ‘good, better, best sort’ of metric, but Chuck Panaccione from Enduro Bearings says this standard is lacking.

What the ABEC standard qualifies is bore diameter (an acceptable variation of the size of the inner bearing hole), parallelism (width variation), and the radial raceway run-out (variations in the groove in which the balls sit).

But Panaccione made it clear that the ABEC system forgoes load handling, ball precision or Rockwell Hardness (material hardness). The folks at Enduro Bearings argue that, for bicycles, the materials are far more important than ABEC ratings and that for most applications, ABEC 3 and 5 are appropriate for all things bicycle.

As for the 7 and 9 ratings, that level of precision is for equipment that sees rotations in the thousands or hundreds of thousands per minute — a tad overkill for cycling!

A quick guide to seals

Two rubber seals – sound technical? Maybe if it’s referred to as 2RS it’ll get your attention? Well, that’s just how tech seals can be…

Seals are kind of a dry and boring topic (pun intended – bearing humor). They have capillary-like action, with regards to cleaning agents and water, and thus their design is critical.

Seals on cartridge bearings can be carefully removed to clean and inject fresh grease, but be warned, this can lead to a ruined bearing if done incorrectly
Thomas McDaniel / Immediate Media

There are three major considerations regarding seals — friction, protection and serviceability.

Friction is a major point of contention for cartridge bearings, and while less is better, a little friction can be an indication of protection. The job of the seal is just that, to keep grease in and contaminants out.

But once you have contamination, can you clean and service your cartridge without damaging the seal?

For most quality bearings, including every bearing Enduro Bearings makes, Panaccione assures “with a small blade and a careful hand, seals can be removed from the inside race for servicing.”

What are bearings made from?

Chromium steel, 440C stainless steel, XD15 super nitrogen stainless, and silicone nitride (ceramic) are all available, and then some.

There’s a good, better and best when it comes to materials, and while it seems harder is better, there is a point of diminishing returns. Ultimately, too hard means  the balls can become brittle, which is no better than too soft.

Balance the application (hub, crank, suspension pivot, etc), how much service you’re willing to put in, and pick a budget — you’re left with plenty of good options from reputable brands, no problem.

Bearings maintenance

Maintenance should include the following tools: bearing removal tools, bearing installation tools, a small flat-bladed pick and a dental pick with a sharp curved edge.

Using the right tools means the bearings and bores don’t get ruined. I’ve worked with both the Wheels Manufacturing and Enduro Bearing tool kits and they both make a frustrating process incredibly quick, painless and precise.

Suspension overhauls can take 15 minutes, and wheel servicing is a 5-minute ordeal.

Servicing bearings finishes with the proper lubricant — talk to your local service providers to learn what’s best for your bike components and riding environment
Thomas McDaniel / Immediate Media

Proper installation may seem simple enough, but misalignment from improper installs are a big cause of premature wear. Also, if you’re working with angular contact bearings, the seals are different colors for a reason! Black seals are meant to face the centerline, while red should face outwards.

Proper bearing maintenance ends with proper lubrication, which could be anything from sticky waterproof grease to thin frictionless lube.

Depending on the application, the type of bearing system used, how often maintenance is done, and the type of environmental exposure the system experiences, dictate the best lubricant.

Bike shops have seen it all, so hit them up on the most appropriate grease/lubricant.

Press fit – yep, we’re going there…

Press fit gained in popularity because of many cross-threading issues at factories. True story. When the assemblers would cross-thread a bottom bracket in a frame during installation it ruined the frame, increasing rejection rates and costing manufacturers money. Frustrating for them, and so press-fit was born… frustrating for us.

That frustration now ends up on our plates and the creaking, play and backing out of cups that stems from poor tolerances have proven an issue for a lot of riders. And while I was quick to point fingers at frame manufacturers, what Enduro Bearings was quick to point back was that it’s not just the frame manufacturer, but also the component manufacturers.

Enduro Bearings is in the business of precision and has said it’s measured several components that are far from spec — both too big and too small. Despite the fact we’re talking about hundredths or thousands of a millimeter, it’s a lot for these applications and so both frame and component manufacturers are to blame.

If you’re constantly dealing with issues due to a lack of bore precision, roundness or parallelism, there are new systems that create a self-contained bearing bores to solve the problem. Enduro Bearings, Praxis, Wheels Manufacturing, Hope, Chris King, FSA and several other brands are making units to stop the problem.

I highly recommend them even if you aren’t suffering from noise because they are serviceable, as opposed to most single-use nylon systems. They also lend themselves to much better performance as a result of the bearing/bore precision inherent in their design.

Show some love

The bicycle is a beautiful thing — art and performance wrapped up in an awesome package. But they don’t roll without the bearings.

You can’t steer, roll, or pedal without them.


So show some love, and keep them rolling smooth by knowing more about your bike from front to back. If your rotating components aren’t smooth, have a look inside to see what you can do for better performance.