YoYo Wiki
Yo-yo ball bearings

Ball bearings, in the context of yo-yo play, were introduced in the early 1990s. They are used to reduce friction while the yo-yo is sleeping. A ball bearing yo-yo can be played in two extreme states. One configuration involves using a thick lubricant in the ball bearing, so that sleep times will be low. This configuration is generally used for looping tricks. The second configuration involves either running a bearing with thin lube in small amounts or cleaning the ball bearing of any lubricant - playing a "dry" bearing. Dry bearings are usually used so yo-yos will be less responsive during string trick play.



Anatomy of a Ball Bearing

As the cross section diagram shows, a ball bearing consists of an outer race (top blue bar), an inner race (bottom blue bar) and balls (grey) that roll in grooves in the races. To keep the balls evenly distributed, some bearings employ a so called cage (green). Since dust inside of the bearing is quite detrimental to its performance, the side walls are often protected by shields (red) that are fixed on - and rotate with - the outer race. The shields can usually be removed by taking out the small steel springs that hold them in place.

In a yo-yo, the bearing is mounted around an axle (light grey) and gripped on the sides by either a bearing seat machined into the inner faces of the yo-yo or by shims (yellow) which are mounted on the axle on either side of the bearing. Since the shields rotate with the outer race, it is very important that the shims do not touch the shields. Many players remove the shields permanently to prevent this, and to allow easier cleaning and inspection.


  • Steel - Historically, most yo-yo ball bearings have been made from steel. Some are stainless, but since stainless steel is much softer than ordinary steel, this reduces the life time of the bearing. That's why many manufacturers (such as Buzz-On Industries) use non-stainless bearings.
  • Ceramic - A more expensive variety use ceramic silicon nitride (Si3N4) balls inside, but retain a stainless steel race and exterior. It is supposed to sleep even longer but can cost from $7 to over $100 for one bearing. Along with that, ceramic bearings are also susceptible to shock damage.

Sometimes bearings are marketed with a corresponding ABEC number. These numbers are often, but incorrectly used to refer to the quality of the bearing. The number is, more or less, a reference to it's dimensional tolerances set up by the Annual Bearing Engineers Committee. ABEC and ISO standards do not cover: radial play, raceway curvature, surface finish, material, ball complement, number, size or precision level, retainer type, lubrication, torque, cleanliness at assembly, packaging and other factors that may be essential to the desired bearing performance.

Usually, yo-yo bearings come as ABEC-3, although more expensive bearings, such as the KonKave bearing, are ABEC-7. However, the majority of yo-yoers are of the opinion that ABEC ratings do not make any difference to yo-yo play, as a higher ABEC rating bearing will not spin any longer.


There are many different bearing sizes, and knowing what size the bearing is in a yo-yoer's yo-yo is important if they want to upgrade the bearings. Using the Buzz-On SPR kits, it is even possible to modify the size of bearing that fits into a particular yo-yo.

Infinite Illusions sizes[]

Infinite Illusions uses a lettering system to simplify bearing choices. These are the most common sizes you may run into. The listed measurements are, in order, Inner Diameter x Outer Diameter x Width.

  • Size A - The A bearing fits most Duncan, Playmaxx, YoYoFactory, ZanNavi and many other yo-yos. Measures 5 x 10 x 4mm, part number MR105. Relatively common in looping and small bearing 5A yo-yos.
  • Size B - This bearing fits small bearing YoYoJam yo-yos, including the SpinFaktor series (but not the HG or the SFX), Kamaitachi, Sunset Trajectory, Matrixx, and certain other yo-yos. It also fits the SuperYo Renegade, and the Spintastics Revolver and Eclipse yo-yos. Measures .250 x .375 x .125 (1/4" x 3/8" x 1/8"), part number R168. Good for looping yo-yos.
  • Size C - Fits large-bearing YoYoJam yo-yos including the Hitman, Lyn Fury, Spinmaster 2 and 3, Big Ben, Patriot, Night Moves 2 and 3, Shockwave 3, the Speeder and the Speedmaker, as well as the YoYoFactory G5 and 888 and many other yo-yos today. This size has become the most popular for competition-level 1A yo-yos. Measures .250 x .500 x .187 inches (1/4" x 1/2" x 3/16") or 6.35 x 12.7 x 4.7498mm, part number R188.
  • Size D - Commonly fits B.I.S.T., HSpinSPYY, and XCube yo-yos. Measures 5mm x 11mm x 5mm. (0.196" x 0.433" x 0.196"), part number 685, or alternatively part number MR115 for the 4mm wide bearing. Some yo-yos made by companies in Japan or the United States had produced yo-yos that use this bearing size, due to its faster rotational speed than the C size.
  • Size E - Fits the Spintastics Tornado 2, Tigershark, Riot, Great White, Comet, Torch, and Firefly, and Yomega small bearing yo-yos such as the Raider. Measures .156" x .312" x .125" (or 3.962 x 7.925 x 3.175mm), part number R155. Similar in size to the bearing used by the YoYoFactory Mighty Flea, and as such, there's often confusion between the two sizes, and some Size E yo-yos may be compatible with the the Mighty Flea bearing (Size K, 4 x 8 x 3mm).


Special sizes[]

These bearings are usually made for a specific yo-yo or specific manufacturer.

  • Size F - A mid-sized bearing featured exlusively in the YoYoJam Fiesta yo-yo. Measures 12 x 3.5 x 8mm
  • Size G - A very small bearing that fits all Custom Products yo-yos. Measures .187" x .375" x .125" (3/16" x 3/8" x 1/8"). In 2008, Custom discontinued the use of this size, switching to A-sized bearings for all of their yo-yo products.
  • Size H - Fits the SuperYo Sonic Spin II and Invader yo-yos. It has an outer plastic housing that allows the bearing to make an amusing buzzing noise as the yo-yo spins.
  • Size I - Fits all Tom Kuhn ball bearing yo-yos. Measures .125" x .312" x .140"
  • Size M - This extra-large bearing fits the YoYoJam Big Yo 2, and is only available through special order. Measures 9 x 17 x 5mm, larger than even an L-bearing!
  • Size K - A miniature bearing designed for the YoYoFactory Mighty Flea, and is smaller than even an A-bearing. Measures 4 x 8 x 3mm, part number MR84. Has also seen use in the Loop 900 and its successor, the Loop 1080. It also appeared in the Duncan Hornet, as well as some yo-yos in Bandai's HyperCluster series. It is similar in size to an E-sized bearing. 
  • Size J - A large-size bearing by Yomega used in yo-yos such as the HyperWarp Heavy Wing, the Hot Shot, the original version of the Maverick, and the Dash. It is smaller than and is discontinued in favor of the C-bearing. Measures 5.98 x 11.98 x 3.96mm. This is compatible with 6 x 12 x 4mm, part number MR126.
  • Size L - A large-sized bearing similar in dimensions to a C-bearing at 6 x 13 x 5mm, so it would be too easy for the uninformed to confuse the two sizes. Seen mostly in ILYY and Oxygene yo-yos.

Specialty Bearings[]

Over the years there have been a few innovations in ball bearings specially designed for the yo-yo market.


Center Trac[]


The Center Trac bearing was developed by YoYoFactory in collaboration with Central Bearing Co. to center the string. It is similar in design and function to the KonKave bearing, but instead of a smooth, curved shape, it is flat with flared edges. YoYoFactory claims that this is to keep the string from bunching up in the center of the bearing. There is also a Gold (see below) version of this bearing available. As of recent, there is a 10-ball variant, known as Center Trac X (CTX for short). It is also referred to as a "UFO-style" bearing by Japanese players. Standard Center Trac bearings come in Size A and Size C. Similar to the KonKave bearing (see below), it had become popular enough that its shape became imitated by non-brand bearings.



The KonKave bearing was developed by Dif-e-Yo in 2003. It is designed to keep the string centered on the bearing and away from the response system. The outer surface of these bearings, is not flat, but slightly concave (as the name implies). Originally, Dif-e-Yo used a bearing that had a groove on the outer race that centers the string. Most Dif-e-Yo yo-yos from 2002-2003 onwards come with a KonKave bearing as standard. For many other yo-yos, Dif-e-Yo offers conversion kits, and the process of upgrading an existing yo-yo thus became known as KonKaving. Comes in Sizes A, C, D, and L. There is also a variant of the Size C KonKave that comes with ceramic balls. Because of its popularity among advanced- and professional-level players, its shape is often imitated by other non-brand bearings.

Trapeze Bearing[]

A v-shaped bearing by Henrys, usable in non-AXYS yo-yos such as the Viper Neo, Viper Neo XL, etc. Available in Size D only, and is exclusive to the Max Gap +TP shim pack. Centers the string to prevent accidental returns and allow for more advanced tricks.


The V-Cave bearing, developed by B.I.S.T., features a single-angled recessed v-shape designed to center the string, similar to the KonKave bearing, and preventing accidental returns.

DS Bearings[]

YoYoRecreation's Double Straight (DS) bearing features a double-angled design on the outer race which centers the string, while also minimizing sleep loss for all string trick styles. This high-end, rust-resistant 10 ball bearing's design has a more gradual angle than most others, and that allows it to center the string more gently during play for a much smoother feel. It was originally a custom bearing that was made specifically for the Dazzler, until the company began to use it in other yo-yos, and even began selling it as a standalone component in May 2014. Available in "C" size only. A higher-quality verison of the DS bearing was recently released, produced by NSK Micro.

Trifecta Bearing[]

The 10-ball Trifecta bearing, developed by Twisted Stringz, combines a KonKave-style shape with a grooved area on the outer race that centers the string for completely unresponsive play. Available in Size C only.

Born Crucial Grooved[]

Born Crucial, the company behind the introduction of the delrin yo-yo into the mainstream, has also produced grooved bearings designed for unresponsive play. The first version of the bearings had a flat outer race, similar to the bearings used in the early Dif-e-Yo collector models, and eventually, the groove is combined with a curved, KonKave-style shape, as the Crucial Grooved Bearing 2.

Pixel Bearing[]

Developed in collaboration by CLYW and iYoYo, the Pixel Bearing features a series of eight steps, starting at the side walls and staggering down to the center of the bearing. This allows the string segments to micro-adjust and move past each other easily during complicated tricks. Available in C size only.




Real ruby balls have been used in experimental bearings made by Wolf Yoyo Works. The exceptional hardiness of ruby reduces rolling resistance and increases durability. The image to the right is taken from the Wolf Yoyo Works Instagram page. The bearing was never officially made available.


The Dorothy bearing used in YoYoFactory's premium yo-yos is also intended to be played dry and not cleaned. It has been speculated that they use Teflon coated parts. These bearings were considered to be very temperamental by some players, as they were prone to locking up. These have been replaced in all YoYoFactory premium yo-yos with the newer SPEC bearings.


The Gold bearing got its name from the coloration that resulted from the treatment process it was given. The gold coloring wears off after a few hours of play. It was commissioned by Taka in Japan and had initially showed promise of being even better than ceramic bearings. However, these bearings have shown a decrease in performance in a relatively short period of time after using them in a yo-yo and cannot be cleaned. They have only been sold at Spingear and Infinite Illusions and newly stocked at YoYoExpert at shop.yoyoexpert.com/product/487/Gold-Plated-Bearings.


Another novel variety of bearing is the Mercury bearing. These were first introduced into the mainstream yo-yo hobby market by Infinite Illusions. The Mercury bearings, named after the Roman God of the Sea, do not contain any elemental mercury. What makes this bearing special is the factory cleaning process that increases spin time and decreases responsiveness.

Mercury Fat Lip[]

A variant of the standard Mercury bearing, the Mercury Fat Lip bearing features a wider inner race to ensure that the shims cannot touch the shields.

Phi 1.618 Super-Bearing[]

The bearing in the Kyo Phi 1.618 features a special coating (Kyle Weems, the designer, won't go into details) that allows it to be played dry. As it is the same size as YoYoJam ball bearings (Size C), it can be used in YoYoJam yo-yos and Dif-e-Yo yo-yos, as well as generally any other C-bearing yo-yo. Kyle ran a series of tests to try to determine the best bearing by using a rig to spin the bearings up to a certain speed and to see how long they took to stop spinning, which resulted in him selecting this bearing.

Electrodynamic Bearings[]

This bearing works with electrodynamic forces induced by a rotor spinning in a permanent magnet field - generating eddy currents. The technique is not requiring any active controller to operate. Electrodynamic bearings are supplied by Magnetal AB (www.magnetal.se)

10 Ball Bearings[]

10 ball bearing has ten balls instead of eight, inside of the bearing. This allows it to be smoother and noticeably quieter than most other bearings. One downside, is that it takes a long time to break in, but once broken in, it will play amazingly.

NSK Bearings[]

These top-of-the-line ball bearings developed by Japan-based NSK Ltd. are machined in such a precise way (to a tolerance of 5/1000) that they need little to no maintanence, employing some very special manufacturing processes for maximum smoothness, and as such, perform extremely well out of the box. Much like the popular KonKave bearing, these NSK yo-yo bearings employ a curved shape on the outer race that centers the string. The standard "Platinum Grade" version performs similarly to most high-end concave-shaped bearings, while a gilded Gold version boasts massive sleep times. However, with such precise machining done in the making of these bearings, the user would have to be careful to prevent them from locking up during play. Available in Size C only.

MonkeyfingeR Design[]

Introduced with their Tri-B return top is the REvolution bearing, a 10-ball composite-material design, which is comprised of ceramic balls complimented with a steel cage and races, making for a smooth and long spin. A variation of this bearing is the Tasmanian Tornado, which features a Center Trac-style shape on the outer race.


  • 1959: Jack Sauer places a ball bearing in a sort of "yo-yo doll", marking the first known use of a ball bearing axle.
  • 1965: Milton Isaacson puts a ball bearing in a "typical" yo-yo.
  • 1984: SKF produces novelty ball bearing yo-yos for promoting their products.
  • 1990: Tom Kuhn releases the first all-metal ball bearing yo-yo, the legendary SB-2.
  • 1991: Yomega releases their first ball bearing yo-yo, the Raider.
  • 1992: Tom Kuhn releases the Roller Woody and Sleep Machine yo-yos, marking the first modern wooden yo-yos to use a ball bearing axle. At the time, most other manufacturers produced yo-yos that had fixed axles.
  • 1997: Playmaxx releases the ProYo Turbo Bumble Bee, the first ball bearing yo-yo to come with a replaceable response system, in the form of BPT (Brake Pad Technology).
  • 1999: Duncan releases their first ball bearing yo-yos as part of the Hardcore series.
  • 2002: Frank Difeo produced the limited Dif-e-Yo Daizzy-Fly, which featured a grooved bearing that centers the string to allow for low-responsive tricks.
  • 2003: Dif-e-Yo introduces the KonKave bearing.
  • 2005: Kyle Weems releases the Kyo Phi 1.618, which included a super-bearing that boasts a non-stick coating that reduces sleep loss to a minimum. YoYoFactory releases the G5, the first yo-yo commercially available to come equipped with bearing-based hubstacks as standard.

More information to be added


To get the most out of your ball bearing, it requires some care.

Breaking In[]

A bearing usually does not perform perfectly out of the box, they need some breaking in. This can usually be achieved by throwing a few long sleepers. Some players stick their bearings on the tip of an electric drill in order to break it in, hence the saying "to dremel a bearing". Alternatively, some players do continuous Gyroscopic flops to help break in the bearing.



How to wash a bearing


Lubrication is often referred to as lube by yo-yoers. Bearings usually run at their least responsive, when they are 'dry', i.e. all lube has been cleaned out of them. This gives them nearly no response at all. The downside of this is a reduced life span, the possibility of rusting, as well as being significantly more noisy. If you decide to use lube, you should clean the inside of your bearing first to remove any old lube or string lint etc, so you can choose how much or how little lube to use.

Unresponsive yo-yo bearings can be slightly oiled with a thin lube. This keeps them from rusting and significantly reduces noise. The main purpose is to give them slightly less response. Trumpet valve oil is one example of a thin lube that makes the bearing nearly as unresponsive as a dry bearing, although it can attack plastic. Most yo-yo stores however now offer yo-yo specific thin lube, which is more effective and doesn't harm the yo-yo.

For yo-yoers who want more response for looping yo-yos, a thick lube is used in much greater quantities. This is most commonly seen in AA play. This makes the ball bearing nearly as responsive as a fixed axle, but with longer sleep times. Types of thick lubes include petroleum jelly and 3-in-1 oil. This is usually applied without cleaning the outside of the shields, to give them more friction against the yo-yo halves.

Bearing life[]

Bearings will eventually wear out, however the way you treat them has a great effect on how long they last. Running bearings completely dry will reduce their lifespan and make the bearing more prone to rust. Using a dremel during the cleaning process will also reduce their lifespan significantly. Bearings should also be kept away from magnets, for if the bearing becomes magnetised the balls stick to any metallic grit and wear out very quickly. Finally, storing bearings within the yo-yo with the string attached for long periods of time is not recommended, because the string will absorb moisture and increase the risk of rust.

External links[]