Knowledge Graph / Materials & Engineering
Bearing systems
The five Shirogorov pivot systems and the washers before them: what each is, which tier carries it, and how each feels.
On this page
The pivot is the part of a Shirogorov that people argue about, buy for, and misdescribe in listings. Five systems exist, plus the bronze washers that came first. The factory itself names four of them and says which tier gets which; the fifth, MRRBS, is a separate system, not an alias for DRRBS. Two teardowns have been published with counts.
The five systems
| System | What it is | Tier | Documented count | Caged or loose |
|---|---|---|---|---|
| SRBS, Single-Row Ball Bearing System | One row of steel balls each side | Early serial standard; still on some serial models (a Quantum Ursus NL listed on SRBS, 2020) | Loose or caged | |
| MRBS, Multi-Row Bearing System | Balls in concentric rows | Serial production; also Sinkevich-collaboration limiteds | 42 x 1.5 mm across three rows on one F95 teardown; varies by model | Loose |
| SRRBS, Single-Row Roller Bearing System | One row of cylindrical rollers each side, riding on line contact | Custom Division; some collaboration projects with other craftsmen | 17 rollers per side on a Custom Division F95, October 2014 | Loose |
| DRRBS, Double-Row Roller Bearing System | Two rows of rollers, often over hardened steel underlays let into the titanium | Sergey Shirogorov’s full customs; a few early Custom Division pieces (Hati 3D Seashell, F95 3D Silk) | ||
| MRRBS, Multi-Row Roller Bearing System | Multiple uncaged roller rows | Custom tier, alongside DRRBS; which pieces carry which is a per-model question | Uncaged by definition |
Before any of them, the earliest folders ran on phosphor bronze washers, which needed a break-in and periodic lubrication and now mark a knife as early. After the washers came single-row balls; the roller and multi-row systems followed. SRRBS was on a Custom Division F95 by October 2014, and MRBS was the serial standard by 2016.
Two configurations sit inside the MRBS family. Asymmetric MRBS and the “Mickey Mouse” pattern (three rows arranged like the silhouette) are layouts, not separate systems. A staggered DRRBS variant originated on custom NeOns.
Why rollers
A ball touches its race at a point; a roller touches it along a line. Line contact spreads the load, which is why the roller systems sit on the upper tiers and why they feel damped and hydraulic rather than fast. The trade is tuning sensitivity: a single row of loose rollers wants its preload set with more care than a multi-row ball bed, and DRRBS pieces go back to the factory or the dealer who sold them for service, and US owners can also go through Recon1. The underlays on DRRBS and the phosphor bronze rings on some roller pieces are there to give the rollers a hardened surface and keep pocket debris out.
The Captive Pivot System
Separate from the bearings but part of the same pivot, the factory’s Captive Pivot System (CPS) forms the rear of the pivot screw as a gear that keys into matching cutouts in the handle, so the pivot cannot rotate during disassembly or adjustment. It appeared on the Hati Gen 3 in May 2022, the first serial model to carry it, and is now standard on recent top serial models and Custom Division pieces.
What each feels like
SRBS is good rather than exceptional and feels like the older system next to anything newer. MRBS is the “Shiro action” most buyers mean: fast, self-centering, and tuned toward drop shut, where the blade falls closed under its own weight once the lock is released. SRRBS and the double- and multi-row roller systems are described as hydraulic, a damped and even travel, and tuned that way on purpose; drop shut and hydraulic are two tunings, not two names for the same thing, and the glossary keeps them apart. Moving up the factory ladder, serial MRBS to Custom Division SRRBS to Sergey’s DRRBS, is reported as a step up in smoothness and consistency each time.
The action smooths over the first few hundred deployments, closing most of all, and the roller systems need less of it than MRBS, which needs less than SRBS. A detent can soften after very extended use if the pivot is never adjusted. A closing that stalls part way and needs a second push has its own page: the service and care FAQ.
Looking after one
Bearings and locks by system covers the cleaning, oiling and pivot-setting procedure for each type. Tools and supplies lists the drivers, oils and solvents.
What this tells a buyer
The bearing system is a tier marker and an authentication cue before it is a performance number. Ball bearings where a listing claims SRRBS means the knife is not what it says. Rollers on a serial-tier model mean either a collaboration project or a claim to check. A DRRBS claim on anything but a Sergey full custom is a claim to check twice; on a Custom Division piece, DRRBS appears only on a few early pieces such as the Hati 3D Seashell and the F95 3D Silk. The tier ladder carries the rest of the cues, and Buying, selling and value carries what the tiers are worth.