SUMC · FLAT TOP CHAIN · SHIMANO
SUMC S12SL PRO Chain — Shimano 12-Speed, Black Rainbow Finish
Flat-top link design, hollow-machined ultra-light construction, and oil-sealed pins built for the long haul — finished in a head-turning Black Rainbow plating.
10,000 KM
Rated Riding Distance, Oil-Sealed Pins
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Flat-Top DesignSUMC is the only manufacturer producing a Shimano-compatible flat-top chain — a design otherwise exclusive to SRAM's own Flattop standard.
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Hollow-Machined Ultra LightPlates and pin shafts hollow-machined to 1-micron precision; pins hardened to 1600+HV with double-nitriding and titanium-nitride coating.
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Oil-Sealed PinsPatented O-ring seals keep lubricant inside every roller, rated for up to 10,000km of riding.
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10 Finish ColorwaysSUMC's widest color range at this tier — build-matching finishes without giving up performance.
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Why Are These Shimano Chains Flat-Top?
A lot of riders simply like the shape and feel of a flat-top chain — but until now, that design was locked to SRAM drivetrains only. SUMC set out to give Shimano riders more options, engineering a flat-top chain built specifically to run on Shimano systems too. The result is a chain shape that was previously off-limits to Shimano users, now available to them for the first time.
Shimano vs SRAM: What Actually Differs
Shimano and SRAM both use the same nominal chain pitch at 12-speed, but each brand tunes inner link width, pin length, and outer-plate chamfering differently to match its own derailleur cage geometry, cassette tooth-ramp profile, and quick-link/master-link design. This S12SL PRO chain is engineered and tuned specifically to Shimano's spec; SUMC also produces a separate SRAM-tuned version of this same tier for SRAM drivetrains. This listing is the Shimano-tuned version.
SL, EL, or No Suffix: What the Name Tells You
SUMC's tier naming isn't just marketing — it describes exactly how the chain is machined. This is an SL (Super Light) chain: it has hollow pins AND cut-out side plates, the lightest construction SUMC builds, bringing this 12-speed flat-top chain down to just 256g. Step down a tier to EL and the pins become solid while the side plates keep their cut-outs, landing at 268.5g. Chains with no suffix at all use solid pins and solid side plates throughout — the sturdiest and heaviest of the three, at 274.3g. As more material is machined away, weight drops and price rises, so you can pick the tier that matches how much you're willing to spend to save grams.
| Tier |
Pins |
Side Plates |
Weight |
| SL |
Hollow |
Cut-out |
256g |
| EL |
Solid |
Cut-out |
268.5g |
| No suffix |
Solid |
Solid |
274.3g |
Why SUMC?
SUMC is the only manufacturer in the world producing a Shimano-compatible flat-top chain, a design otherwise exclusive to SRAM's own Flattop standard. Every S12SL PRO chain is hollow-machined to 1-micron precision with pin shafts hardened to 1600+HV and finished with double-nitriding plus a titanium-nitride coating, keeping weight down without sacrificing strength. Patented oil-storing seals lubricate every pin from the inside out for up to 10,000km of riding, and the finish is salt-spray tested for 1000+ hours of corrosion resistance. This Black Rainbow finish is one of 10 colorways in the S12SL PRO line — SUMC's widest color range at this tier.
Specifications
| Speed |
12-Speed |
| Compatibility |
Shimano 12-speed drivetrains |
| Link Design |
Flat-top (crescent) outer plate |
| Chain Pitch |
1/2" x 11/128" |
| Finish |
Black Rainbow |
| Links |
126 |
SKU: SMC-S12SL-PRO-BKRNBW
