SUMC · FLAT TOP CHAIN · SHIMANO
SUMC S12 PRO Chain — 12-Speed Shimano Flat-Top Chain in Rainbow
SUMC's S12 PRO brings the flat-top (crescent) outer-plate link design to Shimano 12-speed drivetrains, finished in a vivid rainbow plating that catches light from every angle.
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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Oil-Sealed PinsPatented O-ring seals keep lubricant inside every roller, rated for up to 10,000km of riding.
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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 12-speed drivetrains share the same nominal chain pitch, 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 master-link design — Shimano's own quick-link versus SRAM's PowerLock/Flattop link. This S12 PRO chain is built and tuned specifically for Shimano 12-speed drivetrains; SUMC also produces a separate SRAM-tuned version of this chain at the same tier.
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 chain carries no SL or EL suffix: it uses solid pins and solid side plates throughout, the sturdiest and most affordable construction SUMC builds for this 12-speed flat-top platform, at 274.3g. Step up to the EL tier and the side plates gain cut-outs, dropping weight to 268.5g. Step up again to the SL (Super Light) tier and the pins become hollow too, for the lightest build at 256g. 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's flat-top Shimano-compatible chain isn't available from any other manufacturer — flat-top link plates are otherwise exclusive to SRAM's own Flattop standard. Every pin is oil-sealed with a patented O-ring, rated for up to 10,000km of riding. The rainbow finish carries a 4-micron anti-corrosion coating that's passed 1000+ hours of salt-spray testing, and it's RoHS/REACH/CPSIA compliant. SUMC backs all of this with a wide range of finish colors to match any build.
Specifications
| Speed |
12-Speed |
| Compatibility |
Shimano 12-speed drivetrains |
| Link Design |
Flat-top (crescent) outer plate |
| Chain Pitch |
1/2" x 11/128" |
| Finish |
Rainbow |
| Links |
126 |
SKU: SMC-S12-PRO-RNBW
