A carbon chainring that doesn't wear out like a carbon chainring.

Carbon where the load is, aluminum where the chain is. That's the whole idea, and it's why RIGEL works where the concept has failed before.

Handcrafted in Barcelona, SRAM 8-bolt direct mount, 6.5mm offset. Available 40T through 50T.

How it's actually built

The obvious objection to a carbon chainring is that carbon teeth would be chewed to nothing by a steel chain inside a season. Gemini's answer is that the teeth aren't carbon.

Inside every RIGEL is a 7075-T6 aluminum core, CNC-machined with the full tooth profile. That's the surface your chain actually rides on — the same alloy used in premium machined chainrings, doing the same job.

Carbon fiber is then laid over that core with the fibers oriented to follow the tooth profile, and the whole assembly is compression-molded at over 100 tons of pressure using a forged carbon process borrowed from hypercar manufacturing.

The result is a ring where carbon carries the structural load — stiffness, strength, and the weight savings — while aluminum handles wear. Neither material is being asked to do the job it's bad at.

Bikerumor described it plainly: crafted "mostly from carbon, but with alloy at the chain's contact surface."

Narrow-wide, no chain guide needed

The teeth alternate wide and narrow to match the alternating inner and outer plates of your chain, phased so every link seats into a tooth shaped specifically for it. That's what holds the chain on a 1x drivetrain with no front derailleur acting as a fence — no chain guide, no clutch workaround, no compromise.

The design is closed rather than spidered, which does two things: it's cleaner through the air, and it stops mud and grit from packing into the ring. A rib on each wide tooth actively helps push debris back out.

78 grams

A 40T in SRAM 8-bolt comes in at 78 grams. Larger sizes scale up from there, all of them well under what a comparable machined aluminum ring weighs.

Worth being clear about what that buys you. This is not a chainring that will win you a race on weight alone — it's tens of grams, not hundreds. What you're buying is the combination: lower weight, lower friction at the chain interface, a stiffer structure, and a component that looks like nothing else on the bike.

Who makes it

Gemini Composites is a small Barcelona operation founded in 2015 by Roland Baides, a bike design engineer who spent two years as chief design engineer at Unno before returning to build Gemini full time. Design, engineering, and carbon production all happen in one workshop.

RIGEL took more than three years of development, over 500 prototypes, and thousands of kilometers of testing, and produced two international patent applications along the way.

Every ring is made by hand in Barcelona. Production is limited by what that workshop can produce, which is the honest version of "exclusive."

Choosing your size

Ring size on a 1x setup determines your entire gear range, so it's worth matching to the riding rather than defaulting.

• 40T — loaded gravel, bikepacking, steep sustained dirt. The lowest climbing gear available here.
• 42T — general mixed-terrain gravel. The most commonly specced size in the category for good reason.
• 44T — fast gravel and gravel racing, or mixed riding with a lot of pavement between the dirt.
• 46T — all-road and fast gravel where you're holding pace on tarmac more than climbing.
• 48T — road 1x and criterium racing. Over a 10-tooth cog this outruns a traditional 50/11.
• 50T — road racing, time trial, and triathlon. The fastest gearing on offer.

Rule of thumb: match or go one tooth larger than what you're running now if you're happy with your range. If you consistently run out of gears at one end, move two teeth in that direction rather than one — the difference is more subtle than people expect.

Compatibility

Interface: SRAM 8-bolt direct mount, 6.5mm offset — SRAM's standard 1x road and gravel offset. It fits any SRAM crankset using the 8-bolt DM interface, including Rival, Force, and RED, and works as a direct replacement for a stock SRAM X-SYNC direct mount ring.

Drivetrains: 1x11, 1x12, and 1x13 speed.

Chains: compatible with 11 and 12-speed chains from both major brands, including SRAM Flattop.

Not compatible with 2x setups, SRAM 3-bolt cranks, Race Face/Easton, or Cannondale Hollowgram — those interfaces exist in the RIGEL line but are not the version sold here.

Living with it

Treat it like any other chainring, with one preference: run a dry chain lube. Gemini recommends it, and dry lube attracts less grit into the tooth interface, which is where wear happens on any ring.

Gemini's position on service life is that real-world durability is effectively comparable to a conventional aluminum chainring. They don't publish a mileage figure, and we'd rather tell you that than invent one. What we can tell you is that the wear surface is the same 7075-T6 alloy a machined ring is made from.

Keep it clean, watch your chain wear, and replace the chain before it stretches — that's what protects any chainring, carbon or not.

Specifications

• Construction: Forged carbon over CNC-machined 7075-T6 aluminum core
• Molding: Compression molded at 100+ tons
• Tooth profile: Narrow-wide, phased for chain retention
• Interface: SRAM 8-bolt direct mount
• Offset: 6.5mm (SRAM standard)
• Sizes: 40T, 42T, 44T, 46T, 48T, 50T
• Drivetrain: 1x11, 1x12, 1x13
• Chain compatibility: 11 and 12-speed including SRAM Flattop
• Design: Closed profile, aerodynamic, debris-shedding
• Finish: Natural forged carbon with molded graphics
• Weight: from 78g (40T)
• Origin: Handcrafted in Barcelona, Spain

Installation

Standard SRAM 8-bolt direct mount procedure. Use a torque wrench and follow your crankset manufacturer's torque values for the 8-bolt interface — do not guess, and do not use an impact driver.

Check chainline after installation. The 6.5mm offset is designed to place the ring at SRAM's standard 1x position, but if you're moving between crank platforms it's worth confirming rather than assuming.

Install a fresh chain if your current one has any measurable wear. Putting a stretched chain on a new ring is the fastest way to ruin the new ring.

Quotation from Bikerumor's coverage of Gemini RIGEL chainrings, referenced for context and not an endorsement of State Bicycle Co. RIGEL and Gemini are trademarks of Gemini Composites S.L. SRAM, X-SYNC, and Flattop are trademarks of SRAM LLC. Specifications subject to change without notice.