At some point you are going to need to change your wheel bearings. This guide aims to help you make the right decision when choosing your replacement bearings.
Any make of bearing will do, right?
Buying cheap, unbranded bearings from platforms such as eBay or Amazon will nearly always get you poor quality bearings (poor materials and poor tolerances) that will not last long. This may suit you just fine, but if you want your wheels to run smooth and free and your bearings to last, then you should go for bearings from a reputable manufacturer (and watch out for counterfeits!).
The bike forums are full of people criticising a certain inexpensive hub manufacturer, saying that the bearings wore out very quickly. Usually these “bad” hubs were sourced from suppliers in Asia who buy the bare hubs and fit very cheap bearings in order to sell them at a low price. A well-known UK company used to supply hubs from the same manufacturer but with SKF bearings and didn’t get the same complaints. One of the reasons that Hope hubs get consistently good reviews is that their bearings last, they use INA bearings.
So who are the best bearing manufacturers? Here are 6 of the best (source: hambini)
NTN, FAG, INA, NSK, SKF, Koyo
These are industrial bearing manufacturers and they make all standard bearings sizes. Bike manufacturers have a habit of using non-standard parts (don’t get me started on bottom bracket standards) so you may find that you need to source your “exotic” bearing from a bike specific bearing manufacturer such as Enduro, Ceramic Speed, C-Bear etc. These manufacturers make decent bearings but tend to charge more.
International bearing standards
Most bearings are built to the standards of one of the following bodies:
ISO – International Standards Organisation
JIS – Japanese Industrial Standard
DIN – Japanese Industrial Standard
ABEC – American Bearing Standard
ISO, JIS and DIN are all derived from the same source and are effectively interchangeable. The tolerances and performance factors are the same although the numbering system may vary from standard to standard. All 3 of these standards grade their bearings 0, 6, 5, 4, 2 with class 0 being the lowest quality and class 2 bearings being super precision
ABEC is not used by any of the large bearing manufacturers but seems to crop up on quite a lot of bike bearings. ABEC bearings are graded 3, 5, 7, 9 with the lower number denoting lower quality. This grading system bears little resemblance to the ISO/JIS/DIN system so you cannot assume that an ABEC 3 bearing is the same quality as an ISO class 0
Chromium Steel, Stainless Steel, Ceramic?
Chromium Steel (often just referred to as Steel) is by far the most popular material for bearings, with good reason. Good wear characteristics, low friction and cheaper than other materials.
Stainless steel is often preferred when water ingress is likely to be a problem (mountain bikes, cyclocross etc.) but they cost more, have more friction than steel and they can suffer from galling (micro delamination that causes pitting and can lead to seizing), but they don’t rust.
Ceramic: Fully ceramic and hybrid ceramic bearings are hyped up in cycling circles for their lower rolling resistance. The downside is their short life and very high cost. For time trials and track racing they could well be worth the extra cost but all the performance benefit is likely to have disappeared after 500-700km. Cheap unbranded ceramic bearings from China are a waste of money.
Rolling Resistance Versus Water Resistance
Most of the rolling resistance of a bearing comes from the seals, so if you want to go faster you can fit bearing with non-contacting seals or even no seals at all. Ceramic bearings will probably have non-contacting seals fitted as standard so bear that in mind when the weather turns bad. Perfect for track racing and dry time trials & triathlons.
Contacting seals keep moisture and dirt out better than the non-contacting version but have a higher rolling resistance. These bearing have the suffix 2RS which literally stands for 2 rubber seals. Confusingly FSA and Enduro badge their non-contacting seals as 2RS. This is the default option for most bike applications
Open bearings, without any seals, are often found in pedals but not in other places on a bike. Some wheel manufacturers use bearings with only one seal in their wheels, presumably to reduce friction. These bearing should always be fitted with the seals facing outwards.
Bearing sizes are always in the format: Inner Diameter x Outer Diameter x Width (thickness) so if you know these dimensions, or have the ability to measure them with a reasonable degree of accuracy, then you should be able to find the right bearing. There are a couple of other things to check though.
Seals: See the paragraph above and select the correct type of seal for your intended use.
Caged or Full Complement: Always caged for rotating bike parts. Full Complement bearings do not have a cage to separate the bearings, instead they have more bearings which touch each other. In bike applications they will only be use for frame pivots and shock mounts on mountain bikes.
Angular Contact or standard Deep Groove bearings? A regular Deep groove bearing is very good at dealing with radial loads (think vertical loads when in a wheel) and not as good at dealing with axial loads (horizontal in a bike wheel). An Angular Contact Bearing is great for axial loads but not as good for radial loads, it also has a higher radial friction. So for wheels a standard Deep Groove or Radial bearing is the best choice. ACBs are use on headsets and can be used on some bottom brackets, but not SRAM GXP or Praxis M30.
Note on ACBs: Shimano and Campagnolo still use cup & cone bearings (a type of Angular Contact bearing) in some of their wheels. Why? Probably because it is cheaper to manufacture. Are they any good? Yes if well maintained but lack of maintenance can lead to wear that could require hub replacement.
Unfortunately there are a lot of cheap bearings being passed off as high quality bearings and you would be unlikely to tell the difference by looking at them. The best way to avoid fakes is to buy from a reputable company who source their bearings from official distributors only.
Fitting your wheel bearings
One of the most common mistakes is to press or hammer the bearing into place with contact to the inner race. This will damage the bearing, increase the rolling resistance and drastically shorten the life of the bearing. Bearings should be pressed (ideally) or tapped in (if you must) with contact to the outer race only.
Care must also be taken to ensure that the bearing is fitted square, a suitable press is ideal but can be pricey. There are numerous videos tutorials on YouTube but bear in mind that anyone can put up a video and the content could be inaccurate, misleading, dangerous, stupid etc. I would stick to videos from bike or component manufacturers.
If you are local to West Malling, Kent, Bike Wheels Direct offer a fitting service. We can supply and fit bearings to most makes of wheels.