Editing Inline skates (section)

=== Bearing shields ===

Inline skate bearings are protected from external contamination primarily through the use of shields. While 608 bearings in general can employ various shield types, inline skating and skateboarding commonly use one of four: non-serviceable metal gap shields (Z), serviceable metal gap shields with a C-ring (ZS), serviceable rubber gap shields bonded to a metal insert (RS), and full-contact labyrinth rubber lip seals (RSL).<ref name="usenet-chen-FAQ-inline-bearings"/>{{efn-ua|name=bearing-sealing-designations|
Bearing shielding and sealing are designated by suffixes that vary between manufacturers. These designations are typically published in technical handbooks and catalogs.<ref name="bds-bearings-complete-guide-bearing-seals-types-designations"/> One NTN suffix conversion table can be found on page 178 of the Bearing Nomenclature Guide by BDS.<ref name="bds-bearings-bearing-nomenclature-guide"/> There is no industry-wide standard that clearly defines when a "shield" becomes a "seal," nor where non-contact shields end and light-contact or non-contact seals begin. Likewise, the skating industry adopts suffixes inspired by those used in the bearing industry, but does not apply them consistently across brands.<ref name="usenet-chen-FAQ-inline-bearings"/> Generally, removable metal gap shields are labeled with the suffix "Z" in a fairly uniform way.See [https://bladeville.com/rollerblade-training-sg-9.html Rollerblade SG9 bearings] ([https://web.archive.org/web/20240814200225/https://bladeville.com/rollerblade-training-sg-9.html archived]). C-ring mounted metal gap shields, popularized by TWINCAM, are rarely marked with a distinct suffix, but when they are, they follow the "ZS" convention used by SKF.<ref name="powerslide-download-guides-bearings-by-wicked"/><ref name="skf-group-rolling-bearings-1152-pages-2018"/> The skating industry’s use of the "RS" suffix typically refers to a non-contact NBR shield that physically resembles the RS/2RS contact lip seals used by INA/Schaeffler, but instead leaves a narrow gap, similar to SKF’s non-contact "RZ" shields.<ref name="miniature-bearings-australia-skate-bearing-faq"/><ref name="fireball-dragon-bearings-6-misconceptions-about-bearings"/><ref name="schaeffler-ina-product-reference-guide-2003"/><ref name="skf-group-rolling-bearings-1152-pages-2018"/> The "RSL" suffix in skating refers to a full-contact labyrinth seal, comparable to SKF’s own RSL low-friction seals, except that SKF RSL leaves small gaps while bending the contamination path.<ref name="fireball-dragon-bearings-6-misconceptions-about-bearings"/><ref name="skf-group-rolling-bearings-1152-pages-2018"/>}}

{{multiple image
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 | image1 = Inline bearings-Bauer ZZ metal gap shield-Gap illustrated-IMG 7649-FRD.jpg
 | image2 = Inline bearings-Bauer ZZ metal gap shield-Gap illustrated-IMG 7644-FRD.jpg
 | footer = Gap between shield and inner race in a Z shield
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'''Z Shields''': Z-type '''metal shields''' are among the most common on 608 bearings. These simple metal shields are labeled "Z" by manufacturers and skate brands. They snap into a groove on the outer race and do not contact the inner race, leaving a small '''gap''' that prevents friction but allows dirt and moisture to enter. A '''non-contact''' gap shield allows the inner race to rotate freely without drags from the shield. Bearings shielded on both sides in this manner are designated "ZZ", and are '''non-serviceable''', as the shields cannot be removed without being bent or deformed. Rollerblade SG bearings are typical examples of ZZ-shielded bearings.<ref name="vandem-longboard-on-skateboard-bearings-the-truth"/><ref name="ntn-snr-rolling-bearings-handbook-2017"/><ref name="skf-group-rolling-bearings-1152-pages-2018"/>{{efn-ua|name=bearing-sealing-designations}}

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 | image1 = Inline bearings-Max ILQ-like Abec 3-C ring removed-IMG 7536-FRD.jpg
 | image2 = Inline bearings-Max ILQ-like Abec 3-Non-removable metal retainer n balls-IMG 7548-FRD.jpg
 | footer = ZS shields released by removing the C-ring
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'''ZS Shields''': ZS '''metal shields''' are held in place by a '''removable C-clip''' (or C-ring) seated in the outer race. Bearings with this design on both sides are labeled "2ZS" or "ZZS". Like Z shields, ZS shields are '''non-contact''' and impose minimal drag on the bearing, but they offer limited protection against dirt and moisture, because of the gap. Their key advantage is '''serviceability''': skaters can remove and reattach the shields without damage, enabling regular cleaning and relubrication to keep bearings working at top condition. SKF manufactures such bearings, and TWINCAM has made this shield style popular with its ILQ inline bearings.<ref name="powerslide-download-guides-bearings-by-wicked"/><ref name="usenet-chen-FAQ-inline-bearings"/><ref name="skf-group-rolling-bearings-1152-pages-2018"/>{{efn-ua|name=bearing-sealing-designations}}

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 | image1 = Inline bearings-TRUE Swiss-Bones REDS-alike-Non-contact shield removed-IMG 7484-2-FRD.jpg
 | image2 = Inline bearings-TRUE Swiss-Bones REDS-alike-Disassembled-Exploded view-IMG 7518-7520-7526-7528-7533-bg-FRD.png
 | footer = Typical single RS shield with removable retainer
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'''RS Shields''': In skating, RS '''rubber shields''' specifically refer to the style popularized by Bones Swiss. These consist of a nitrile rubber shield bonded to a metal insert. The shield snaps into the outer race and can be pried off for maintenance. RS shields are '''non-contact''' and offer improved protection over Z and ZS shields, particularly against microscopic particles. However, moisture can still penetrate and cause corrosion. Many popular skate brands avoid double-shielded 2RS bearings and instead use a single RS shield, leaving the opposite face of the bearing open for ease of maintenance. This open side is positioned inward when mounted inside the wheel hub, which effectively protects it from external debris. This configuration allows skaters to remove the plastic retainer and lubricate the bearing balls without needing to remove the shield, providing both protection and convenient access for '''servicing'''.<ref name="miniature-bearings-australia-skate-bearing-faq"/><ref name="fireball-dragon-bearings-6-misconceptions-about-bearings"/><ref name="schaeffler-ina-product-reference-guide-2003"/><ref name="skf-group-rolling-bearings-1152-pages-2018"/>{{efn-ua|name=bearing-sealing-designations}}

[[File:Kugellager.jpg|thumb|right|160px|Bearing packed with grease]]

'''RSL Seals''': '''Full-contact labyrinth rubber seals''' (RSL) represent a stark departure from non-contact shield designs. These seals feature a '''lip''' with a labyrinth-shaped profile lightly touching a surface of the inner race. This configuration effectively seals out not only dirt but also moisture. Typical bearings with non-contact shields use light oil as a lubricant, since grease tends to trap any debris that makes it past the shield, accelerating internal wear. Bearings with RSL seals, however, are far more resistant to contaminants, allowing them to be packed with heavy, '''viscous grease'''. This grease provides '''longer-lasting lubrication''' and superior protection in sealed environments compared to the '''lighter oil''' formulations used in non-contact shielded designs.<ref name="fireball-dragon-bearings-6-misconceptions-about-bearings"/><ref name="skf-group-rolling-bearings-1152-pages-2018"/>{{efn-ua|name=bearing-sealing-designations}}

RSL-sealed bearings are designed for '''near-zero maintenance''', with the tradeoff being '''increased bearing drag'''. Contact seals alone can account for about 60% of total bearing friction, with an additional 30% from the viscous grease, and only 10% from rolling friction between the balls, cage, and raceways. In addition, Heavily-greased bearings do not spin freely when unloaded. However, when subjected to a skater’s full body weight, the pressure forces the grease out of the ball paths, enabling smooth and efficient wheel rotation under load. Dragon Bearings offers several 2RSL models featuring full-contact labyrinth seals on both sides of the bearing.<ref name="hambini-ceramic-vs-steel-bearings-friction-analysis"/><ref name="fireball-dragon-bearings-6-misconceptions-about-bearings"/>