The bearings of a bicycle are its most important components: a bicycle will not move without them.
This comprehensive guide looks at each category of bicycle bearings, looking at the characteristics of each, the engineering logic behind its design, and the key components in which it is used.
CONTENT
Why is a bearing called a "bearing"?
radial and axial force
4 types of bicycle bearings
- cup and cone
- sealed bearings
- Needle bearings (rollers)
- caps
main component bearings
- bottom bracket bearings
- headset bearings
- wheel hubs
WHY IS A BEARING (bike) CALLED 'BEARING'?
Because the bearing, as a unit made up of several components,BONEa lot.
In formal terms, bearings are components within a machine that mediate the force between two other components in which one part supports the other.
The bearing allows(1)linear motion or(2)Rotation about a support axis.
Bicycle bearings exclusively allow the latter: rotation around an axis.
First, let's clarify these terms and concepts, as we'll need them when we take a closer look at the different types of bicycle bearings.
The ball and race of a bearing.
Two categories of components support the load: 1. the race 2. the ball
Oneexteriorrace is separate from oneinternalrace for the balls that follow along it.
forces or loadconsequenceIn the spheres through the inner and outer races there is a variable combination of radial and axial forces.
Force: Radial and Axial
The bearings allow rotation.ofan axis (axis) or rotationaroundone shaft (arrow) under load.
The two types of force that define this load are radial and axial.
radial load
Radial load is the force applied at right angles to the shaft.
This cross section of a cartridge/sealed bearing (we'll cover sealed bearings in detail below) illustrates the perpendicular direction of force on the ball.
axial load
With axial loading, the force is applied along the axis of the shaft.
In theory, radial and axial loads are mutually exclusive.
But in practice, in the real world, they interact to varying degrees.
Being aware of, and controlling, this interaction keeps a bearing performing at its optimum level.
Radial contact x angular contact
The load on bearings consists mainly of radial and axial forces.
The grade of each defines the type of bearing installed in a given component.
Therefore, angular contact bearings incorporate a significant axial load as well as a radial load.
The alpha angle (α) is the contact angle between a ball and the fairways.
Where you have a single radial nip, the inner and outer races are perpendicular to each other with zero offset; α is zero - there is no angle.
When one or both tracks are displaced, α has a value and has angular contact.
With regards to bicycles, cup and cone bearings are angular contact bearings.
FOUR TYPES OF BEARINGS
There are four types of bearing assemblies used on bicycles:
- cup and cone
- sealed
- needle, and
- (LSL) buchas
Cup and cone bearings were the original form of bicycle bearings, but have been largely superseded by sealed bearings.
Needle roller bearings have been used in pedals for some time and are now finding application in some new suspension fork designs.
Bushings are used in pedals, derailleurs, suspension pivots, seatposts, and brakes.
cup and cone
The original form of bearing frame for BBs, headsets, hubs and pedals where all parts (cups, cones, ball bearings, cage, truss rod, washers and locknuts) require precise assembly and adjustment.
The cup functions as the inner race, the cone is the outer race with the bearings between the two.
The original cup and cone shape used loose bearings, while the balls for modern cup and cone assemblies are mounted in cages.
A cup and cone set is actually aangular contactBearing in which significant axial and radial force is applied by tightening a threaded nut or washer against the cone.
Setting the correct "preload" is important for optimal rotation.
The cone should be tight enough against the balls that there is no play that will cause rapid wear.
If the cone is too tight, the movement of the balls will be restricted: a tight bottom bracket makes it difficult to pedal; a tight-fitting headset makes for a treacherously stiff ride.
sealed bearing
Sealed bearings consist of balls mounted in a cage held between an inner and outer race and are the most common type of bicycle bearing.
Grease is injected into the cage during manufacturing and the unit is sealed with one or two removable seals.
Sealed bearings with two removable seals are plain on both sides.
They are usually installed on cartridges and cups, and sometimes directly on a bicycle frame.
Sealed bearings with a removable seal are used for integrated headsets.
The beveled edge of the outer race completely surrounds the cage with the removable seal covering the cage on one side
A sealed bearing is technically a variant of the cup and cone bearing, or vice versa if you prefer, since the cup is the inner race and the cone is the outer race.
Carga radial vs Carga axial
Sealed bearings are designed to withstand considerable radial loads andMinimumthrust load.
It is important to avoid subjecting sealed bicycle bearings to even light axial loads, for example, during installation on a bicycle.
Excessive (sideways) pressure from an installation tool can misalign the inner race with the outer race.
Sealed Bearing Numbering System
Sealed bearings are manufactured and identified by a 4-digit numbering system.
6806, for example, identifies the sealed bearing used in BB30 assemblies.
Ofirst numberit is usually a 6 or a 7:
- 6 is aditchsphere rotating
- 7 is a single row angular contact bearing
Deep groove ball or radial bearings are the most widely used types of ball bearings.
The name refers to the fact that they fit into the grooved inner and outer races of a sealed bearing.
Osecond numberis the outside diameter of the bearing and does not designate any specific coding category.
It simply follows a sequence, and the higher the number, the stronger the bearing: the thicker the raceway and the larger the ball size.
The last two digits refer to the size of the bearing ball.
- 00 = 10mm
- 01 = 12 mm
- 02 = 15 mm
- 03 = 17 mm
- 04 = 20 mm
Starting with 05, the convention is to multiply the digits by 5. Thus, 05 = 25mm; 06 = 30mm.
Therefore, the 6806 contains a 30mm deep deep groove ball bearing.
How efficient are sealed bearings?
The advantage of sealed bearings begins with the precision of their manufacture.
The lanes are as finely machined as the balls that ride them have ever been; tolerances are good.
Sealing along with the correct amount of grease applied to the bearing housing prevents the ingress of contaminants.
It's inThe #1 reason a sealed bearing wears out is due to the effect of dirt and sandwho quickly degrades balls and runs.
When you judge performance, you assess the degree of friction of
- or seal it
- the fat
- rolling friction
A rough average across various brands allocates 10-15% to rolling friction, about 30% to grease, and the rest to seals.
Yes, the seal is in the way, which is understandable since the spheres are in constant contact with it.
A metal cage is also more efficient than a plastic cage (usually high performance polyamide).
For a sealed bearing headset, it doesn't matter.
However, for other components that operate through millions of cycles of use, where optimal performance is important, a metal cage is better.
What about ceramic bearings?
First of all, ceramic bearings are designed for high-speed applications - that's where the advantage manifests itself.
Sustained RPM from bottom bracket rarely exceeds 100; Wheel hub revs are higher, but still can't be classified as high speed.
in second placeSealing, grease and rolling friction are the three variables that affect performance.
Rolling friction, which is the variable target of ceramic bearings, is the least important of the three.
Probably only the upper level of professional cyclists need to be concerned with performance enhancement, given the minimal advantage AND high cost of ceramic bearings compared to steel.
Needle (or "roller") bearings
Just out of curiosity, it is possible that this type of bearing predates the invention of the wheel.
The ancient Egyptians rolled the huge stone blocks used for the construction of tombs on wooden rollers, technically roller bearings.
Needle bearings have been most commonly used in pedals until recently.
With the advent of gravel bikes and new suspension fork designs offering an alternative to the classic double stays, needle roller bearings have found a new application.
Four sets of needle roller bearings, one for each side, allow up to 32mm of travel in this fork designed for gravel and e-bikes.
In this type of application, the structure of the needle roller bearing is simple: a nylon base ('inner' race) and an alloy face as the 'outer' race.
An external grease fitting allows periodic dispensing of grease to the bearings (and springs) to ensure bearing longevity.
caps
The bushings are used in jockey wheels of higher end derailleurs, pivots, seat posts, some drivetrains, suspension and brakes.
The most technically advanced are the LSL (Lightweight Self Lubricating) bushings that are used in pedals, for example.
The idea is that the lubricant is slowly released over time through surface-to-surface friction.
This is accomplished in a number of ways, one of which is a thin layer of Teflon on the surface that mediates friction for wear.
Another method is sintered lubricant in the bushing body that releases and lubricates as the temperature rises.
Good quality pedals have an LSL bushing fitted to the outer edge of the spindle, with a sealed or needle bearing for the crank end of the spindle.
fat
It is possible to remove a bearing from its seat in a BB cup, hub (tricky... more on that below) or flange on an integrated headset, by far the easiest.
Fats are classified according to theirNLGI number or degree of consistencywhich describes its hardness in a range from 000 to 6.
Bicycle grease is around a 1 or 2 on the scale.
For bicycle bearings, sealed or not, you can't go wrong with a lithium grease.
But of course, there are plenty of bike-specific brands out there with a product to get the job done.
BIKE BEARINGS
A bicycle consists of several axles and load-bearing struts: frame tubes, axles, and spindles.
Shafts do not rotate, but form a fixed support around which a component rotates; a bearing allows rotation.
The spindles rotate (thereforespindle) around a fixed point, a bearing that allows rotation.
bottom brackets
The only bottom brackets that don't use sealed bearings these days tend to be very cheap road bikes and entry level BMXs.
Depending on the bottom bracket specs, a classic bike can be upgraded to accept a bearing cage or even a sealed bearing (we've covered that regarding headsets).
cup and cone bearings
A common cup and cone shape is on older or basic bikes.
Instead of being loose, ball bearings tend to be caged.
They are also often fitted with one-piece cranks.
This is for a BMX bike that can be upgraded to a sealed bearing system by installing adapters that accept a cartridge bottom bracket.
BB cartridges have small sealed bearings pressed into the cartridge that cannot be replaced; when a bearing fails, replace the cartridge.
The lock nut prevents the circlip from vibrating loose while riding the bike.
Unscrew the locking ring/cone holding the cage in place.
With this setup, the cone contacts the cage, not the balls.
The cone continues to regulate bearing preload and if the lockring is too tight, crank rotation is restricted.
sealed bearings
Sealed bearings dominate the mid to high bottom brackets.
Install (chained or threaded)something lessslightly pressed) into the BB shell in cups, or directly as on the BB30 and similar systems.
The smaller sealed bearings are installed in the lower cartridge holders.
Once pressed into the cartridge, they cannot be replaced or repaired. When a bearing wears out, replace the cartridge.
Larger bearings last longer, all other things being equal (excluding differences due to load and externally introduced contaminants).
Externally mounted bottom brackets can accommodate the largest sealed bearings.
Sealed bearings are pressed into cups at the factory, and while they can be replaced when worn, specialist tools and careful technique are required.
These bicycle bearings are also double sealed: a dust cap is placed over the bearing cup in the small gap between the sealed bearing seal and the cup rim.
The press-fit bottom bracket revolution put sealed bicycle bearings back inside the bottom bracket shell.
The sealed bearings are not as small as those installed in the lower shell holders, as the inner diameter of the bottom bracket shell has been increased to allow for larger bearings.
HEADSET
Like the BB, headsets originally consisted of loose bearings mounted in a cup and cone.
Once sealed bearings took over, threaded cup-and-cone headsets transitioned to threadless semi-integral designs and then to integrated mounts that are now standard on mid-to-high-end bikes, excluding classic bikes. (Check the post onheadphone press).
Ascable integrationBecomes standard on mid-range and high-end bikes, bearing sizes have increased, though the main design principles remain the same.
A key difference to headsets is that radial load on the top bearing is close to zero and axial load is minimal, as the only source of load is the rider's weight on the handlebars.
The preload of the head bolt or cone (on integrated headsets) is the source of load for the headset's upper bearing.
However, the axial load on the bottom bearing is higher as it supports the weight of the rider in addition to the preload.
Since loading along with external contaminants are the main variables that determine bearing life, bearings that are serviced frequently should last much longer than BB or hub bearings.
cup and cone
The original design consisted of loose bearings sitting in a cup with a cone that fitted over the top into a threaded steering yoke.
Later versions replaced the loose balls with a cage.
The lower caged bearing rests on the raceway; the ball bearings fit into the cup installed in the main tube.
Sealed
Switching to a semi-integrated headset meant doing away with the threaded headset and using sealed bearings that wrapped around the cage on three sides.
The lower beveled edge fits over the headset cups installed in the head tube.
OR (no thread)helmsmanslides up through bracket; the remaining washer, cap, and screw complete the assembly.
The wired headphones video provides a detailed overview.
Integrated assemblies work with frames designed to directly accept the chamfered edge of a sealed bearing in flanges at the top and bottom of the main.
Needle roller bearings instead of a bearing cage
Needle bearings have been used instead of ball bearings in some threaded headset designs.
Instead of a cage with spherical steel balls, an elongated conical cage contains
WHEEL HUB
Many bikes still rely on loose bearings in a cup and cone assembly, although most use sealed bearings.
cup and cone
The wheel hub body functions as a bearing cap.
The cone holds the balls along the axis of the wheel and is prevented from loosening with a lock nut.
sealed bearing
Instead of a cup to seat loose bearings, a sealed bearing is installed in a cavity machined in the outside diameter of the bearing.
A rear wheel is usually messed up with the freehub body, although it's not difficult to remove and access the sealed bearing.
FINAL COMMENTS
The life of a bearing depends on the bearing.
- Quality
- Carry
- Maintenance
Good quality bearings work better and last longer.
But the service life is highly dependent on the degree of load that is applied to the bearing during its service life.
The higher the radial load on the bottom brackets and wheel hubs, the shorter the wear life, all other things being equal.
Bottom bracket bearings used at low RPM with high torque don't last as long as bearings used at high RPM and low torque, for example.
Also, clean bearings last much longer than dirty ones.
In either case, flush the bearings and clean them, although it is often easier to replace sealed bearings than to remove the seal, wash and re-lube.
Maintaining your bike's bearings, and maintaining your bike in general, is key to keeping your kit running its best for longer.
FAQs
How do I know which headset bearings I need? ›
If you have the stock or original headset bearings, you can measure the outside diameter of those bearings to be sure. You'll likely find numbers like: 41mm, 41.8mm (we round up and label this 42mm), 47mm, and 52mm.
What bearings are best for bike hubs? ›Hybrid Ceramic: steel rings and ceramic balls are the gold standard for bicycle wheel bearings. More durable than high quality steel bearings. Built specifically for road or off-road use.
How do I know what bearings I need for my bike? ›A cartridge bearing's size is determined by its inside diameter (ID), outside diameter (OD) and width. 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.
What are the different bicycle bearings? ›TYPES OF BEARINGS FOR BIKES
Loose-ball, caged-ball, bushing, needle and cartridge are the main types of bearings found in cycling frames and components. The least complex is the bushing style of bearing.
A god rule of thumb is to tighten your headset cap bolt until it is causing some friction with steering and then back it off until it's tight enough to keep the stack neatly in place. This is typically 1/8th to 1/4 of turn. Give your headset spacers a twist. You should not be able to move them much, if at all.
What is the common headset bearing size? ›The standard sizes are 1 inch, 1 1/8 inch, 1.25 inch and 1.5 inch steerers. You may occasionally come across a 1-inch threadless steerer, but you're more likely to find a threaded steerer in this size. 1 1/8 inch threaded steerers are, however, quite common.
Who makes the best bike wheel hubs? ›- Industry Nine Hydra. So many points of engagement. ...
- DT Swiss DT350. Hubs that will outlast your wheels, and won't bankrupt you. ...
- Hope Pro 4. Ideal for mucky UK conditions. ...
- Chris King ISO. The buzzy bee gold standard. ...
- Shimano Saint M820. ...
- Onyx Racing. ...
- Project 321. ...
- White Industries XMR.
We use sealed so the bearings are protected from road debris and weather, so they spin cleaner and with less friction for longer. Sealed bearings perform as well or better than loose bearings, without the maintenance.
What makes a good bike hub? ›Good-quality bearings, sealed and protected from dirt and water, are the key to long and healthy hubs. Older or less expensive hubs may use cup and cone bearings, which contain two rings of loose ball bearings that sit in 'cups' inside the hub body, and are secured in place by conical nuts known as 'cones'.
What is the difference between Grade 25 and Grade 300 bearings? ›The grade number refers to the tolerance per millionth of an inch. A grade 25 is accurate to 25/1,000,000 of an inch. Less expensive ball bearings may be grade 300, which are less round, at 300/1,000,000 of an inch.
How do I know my headset size? ›
You will need to measure (in millimetres) the inside diameter (ID) of the top of the head tube (above pic) and the bottom of the head tube (pic below). Measurements are rounded to the nearest millimetre. Example: a tapered frame with a 44mm upper ID and a 56mm lower ID.
What is the difference between 6000Z and 6000ZZ bearing? ›The 6000 Deep Groove Ball Bearings is an open style bearing. The 6000Z ball bearing is a single row raceway and single shielded. The 6000ZZ ball bearing has a single row raceway and it is shielded on each side.
What are the three 3 commonly types of wheel bearings? ›- Delrin Bearing.
- Roller Bearing.
- Sealed Precision Ball Bearing.
There are four types of hubs available: the track hub, the flip flop hub, the freewheel hub or the cassette hub.
How tight should bike bearings be? ›As loose as possible without play. Bearings are supposed to have some amount of preload, which is a fancy name for being a bit tight as opposed to being loose. There should never be play once adjusted and on the bike.
How do you know if your bike headset is too loose? ›TEST IT Squeeze the front-brake lever with one hand while grabbing the headset (right where it meets the frame) with the other. Rock the bike back and forth. If you feel play in the headset, it's loose.
Do you tighten stem or top cap first? ›First with how to tighten a headset, loosen all the bolts on the stem that tighten down onto the fork. Secondly, take the top-cap bolt on the top of the steerer tube/fork completely off. The top cap will now come off as well.
Can you ride with a loose headset? ›Keep It Tight
Never ride with a loose headset. Improper bearing preload damages headsets and frame head tubes.
To measure the outer diameter of a bearing, place the jaws of your vernier caliper around the outside of the bearing and close it until it meets the outer edge of the bearing. It should be a snug fit, but not tight. Now, you can read the value on the caliper to find the outer diameter measurement.
How much space should be between headset and stem? ›Ensure there is a 3 to 5mm gap between the steerer tube and the top of your stem/spacer. This will ensure there's enough space for the headset top cap to clamp down and pre-load the headset bearing.
Do you need to press headset bearings? ›
It's important that your headset cups — the steering bearing parts that fit in the frame — are tight and secure. Here's how to press them properly into place. If your steering doesn't turn smoothly, your bike won't handle right.
What is the most durable hub? ›Similarly when it comes to freehub material, steel is the most durable, it resists bite best and if you are using a pawl and ratchet system (as Phil do) then it will be the most durable there too. They use a very high quality ABEC 10 bearing.
How do I know if my hubs are good? ›- Roaring or rumbling noise.
- Vibrating or loose steering wheel.
- The vehicle pulling to the side when braking.
- Uneven rotor and brake pad wear.
I ride about 3,000-4,000 miles a year and my rule of thumb is to do the hubs every 300 - 500 miles or so, and the bottom bracket twice a year.
Why do Sealed bearings fail? ›The majority of bearing failures occur because of improper lubrication. Lubrication failure can occur if the wrong lubricant is used, if not enough lubricant is applied, or if the bearing has been exposed to excessive temperatures that have caused the lubricant to degrade.
Can you lubricate a sealed bearing? ›If you are using a shielded bearing or an orange seal bearing you can apply the oil to the bearing with the seals/shields intact. If you are using a contact sealed bearing or grease you will need to remove the seals/shields to apply the lubrication.
What size hub do I need for my bike? ›Choosing a hub
Hubs are generally 100mm wide in front and 130mm wide in the rear for road bike frames; mountain bikers generally use 135-142mm front and rear hubs to allow space for disc brakes, which require extra material on the outer edge of the hub for mounting the disc.
Wheel bearings have an average lifespan of 136,000 to 160,000 km (approximately 85,000 to 100,000 miles). This is only a rule of thumb though, the actual lifespan of a wheel bearing depends on the quality of the wheel bearing and the operating conditions.
How tight should a bike hub be? ›Press it against the bearings and rotate it to check it's seated correctly. Refit the cone to the non drive side of the axle and tighten it until contacts the bearings. It doesn't need to be very tight – finger-tight will do. You can then spin the axle to make sure it rotates cleanly.
What type of bearing is best for high speed? ›Angular contact bearings are the best bearing choice for high-speed applications. One reason is that the balls are smaller and smaller balls weigh less and produce less centrifugal force when rotating.
What is the best bearing grade? ›
Specifically, thanks to its smaller runout and axial play, an ABEC 7 bearing will perform better and last longer in high speed applications, than an ABEC 3 rated bearing. So, if you need a super precise, long-lasting bearing, ABEC 7 is probably the bearing for you.
Which bearing is fastest? ›Bronson Skateobard Bearings are dedicated to their name. They advertise their bearings as the fastest, strongest, longest lasting, longest spin skateboard bearings ever made. Their next generation bearings have really proven popular. Their G2 bearings are Bronson's answer to Bones REDS, an affordable option.
What do I do if my headset is too big? ›A common trick to make the headband of headphones tighter is to place the headphones over something (like a stack of books) that is slightly smaller than the headphones currently are and then wrap the headphones with a cord or elastic band to squeeze the headphones inwards to make them tighter.
How do I know what forks will fit my bike? ›Take your existing front wheel out and measure the current axle diameter to work out further narrow down what fork your bike can accommodate.
What size bearings for 44mm headset? ›44mm MTB Headset Top Cap Bearings 28.6mm (1-1/8") Tube Fork Aluminum Alloy Bike Front Fork Stem Headset Bike Nuts Replacement.
Which is better RS or ZZ bearing? ›RS provides a better seal but more rolling friction than 2Z. RS - Bearing with rubber seal on one side, one side open. 2 Z / ZZ - Bearing with a metal seal on both sides.
What does ZZ mean on a bearing? ›2 Z / ZZ - Bearing with a metal seal on both sides. Z - Bearing with a metal seal on one side, one side open. E - Reinforced Design. P2 - Highest precision.
What is a 609 bearing? ›The 609 is a 9 mm Ball Bearing that can be used in many rotary and factory automation applications. The 609 Miniature Ball Bearings is an open style bearing. The 609ZZ ball bearing has a single row raceway and it is shielded on each side. The 609DDU, 609LLU ball bearing are shielded by two rubber seals on each side.
Which wheel bearing fails first? ›The most common failure pattern for wheel bearings is for those on the passenger side of the vehicle to fail first. The passenger side bearings are exposed to the most standing water in the gutter.
What is the most commonly used bearings? ›The most commonly used bearings are Deep-Groove Ball Bearings. Thanks to their simple design, they are easy to maintain and not as sensitive to operating conditions thus are used in a wide range of different applicaitons. In addition to radial forces, they absorb axial forces in both directions.
Which is better roller bearing or ball bearing? ›
Choosing a Ball or Roller Bearing
As a general rule, ball bearings are used at higher speeds and lighter loads than are roller bearings. Roller bearings perform better under shock and impact loading.
The quick release axles are cheaper, lighter, and easier to remove whenever needed without a single tool. The thru axles offer more stability, better handling, and improved brake performance, plus they are thicker and more durable for a safer option.
What is the difference between boost and non boost hubs? ›What is Boost? Boost refers to front hubs which are 10mm wider and rear hubs which are 6mm wider than 'standard. ' Boost front hubs use the same diameter 15mm front and 12mm rear axles. By making the hubs wider wheels can be built which are stiffer, and more clearance is available for 11 speed drivetrains.
Are hubs outdated? ›Hubs are therefore considered obsolete and switches are commonly used instead in modern LANs. Hubs have numerous disadvantages over switches, such as: they are not aware of the traffic that passes through them. they create only one large collision domain.
What happens when you over tighten bearings? ›“Excessive preload will cause excessive friction and the bearing will run hot, compromising lubrication and eventually leading to flaking (material coming off) at the large end of the rollers/races,” he says.
What are the symptoms of an over tightened wheel bearing? ›The most common and often most-identifiable symptom associated with a bad wheel bearing is noise coming from the wheel or tire area of the moving vehicle. You may mistake this as engine noise, but when you listen closely you are likely to hear grinding or grating that gets louder as the vehicle accelerates.
What is the best bearing for bicycle? ›Radial bearings 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.
How do you know which bearing to use? ›Small-to-medium-sized loads usually work best with ball bearings. Heavy load applications usually work best with roller bearings. Determine the rotational speed of your application. High speeds (RPM) usually work best with ball bearings and lower speeds usually work best with roller bearings.
How do you know which bearing is right? ›Select a bearing that matches the dimensions of the shaft or housing from the bearing boundary dimensions table. Check that the type of bearing you have selected is appropriate by using the "Performance comparison of bearing type" with the bearing usage criteria.
How do you know what size your bearings are? ›To measure the outer diameter of a bearing, place the jaws of your vernier caliper around the outside of the bearing and close it until it meets the outer edge of the bearing. It should be a snug fit, but not tight. Now, you can read the value on the caliper to find the outer diameter measurement.
How do you determine the number of bearings? ›
Measuring your bearing: Most bearings are measured in three ways, the inside diameter or (ID), the outside diameter or (OD) and the width or (W). It is important to note that our bearing measurements are all done in the following order: Inside diameter (ID) x Outside diameter (OD) x Width (W).
What are the 3 rules of bearings? ›- Always measure the angle in a clockwise direction.
- Always measure the angle from north.
- Always give a 3-figure bearing (E.g. 030° instead of 30°)
Specifically, thanks to its smaller runout and axial play, an ABEC 7 bearing will perform better and last longer in high speed applications, than an ABEC 3 rated bearing. So, if you need a super precise, long-lasting bearing, ABEC 7 is probably the bearing for you.
What are the three common bearing types? ›The most popular types of bearings are ball bearings, Tapered Roller Bearings, Ball Thrust Bearings, and Roller Thrust Bearings etc.
How tight should bearing fit? ›tight to 0.004 in. tight. For a tight fit, the wheel hub inside diameter (ID) should be smaller than the outer race OD by the fit values shown on the tables. For inner race fits, the spindle OD should be smaller than the inner race bore within the loose fit range.
How do you check for bearing misalignment? ›Misalignment in a failed bearing can typically be diagnosed by examining the rolling element path inside the bearing. As bearings rotate, the rolling elements generate a wear path on the inner and outer raceways.
What is bearing number examples? ›For example, R4-3RS is the bearing number. Here, R4 indicates the inch bearing. R4 also denotes the bore size of the bearing. Mainly, R4 is equal to 4/16 or 1/4th of an inch.
Do I need 7mm or 8mm bearings? ›Those refer to the inner diameter of the bearing and the size of the axle its going on. Most of the new skates use 8mm axles so the standard 8mm bearings would be needed. The older models, and high end skates use 7mm axles so they would need the 7mm bearings.
What does ZZ mean on bearing? ›2 Z / ZZ - Bearing with a metal seal on both sides. Z - Bearing with a metal seal on one side, one side open. E - Reinforced Design. P2 - Highest precision.
What does J mean on a bearing? ›“J” Type: Two piece ribbon consisting of two halves that are assembled one half from one side, and the other half from the opposite side. Fold down tabs secure the two halves. This type of cage is guided by the balls. “Loose” clinch type provides lower torque.
What does C3 mean on a bearing? ›
Internal clearance being C3 means that the bearing has room for expansion if needed between the races of the bearing, whilst holding the outer ring and moving the inner ring in a radial movement you will detect a little amount of play between the two rings.