Bicycle Chain Standards Explained: Speeds, Widths & Compatibility | BikeQuiver Cyclopedia

Also called: 1/2" pitch, 12.7 mm pitch

12.7 mm (0.5 in) from pin center to pin center

The universal constant of bicycle chains: the distance between consecutive pins (rivets) is half an inch on essentially every bicycle chain made in the last century. Because pitch never varies, any chain meshes with any bicycle sprocket; all compatibility questions come down to width and plate shape, not pitch.

Why it exists: Inherited from early roller-chain industrial standards and frozen in place because every sprocket, chainring, and chain tool in the world assumes it.

Typically found on: All bicycles of every type and era

Also called: 1/8 inch, 3.2 mm internal, BMX/track chain

3.18 mm (1/8") internal width; roughly 9 mm external; 1/2" pitch

The wide, heavy-duty chain family used where the chain never has to shift sideways: BMX, track/fixed-gear, most single-speed bikes, and many bikes with internal-gear hubs (gears sealed inside the rear hub). Its thick plates tolerate abuse and it usually closes with a simple reusable clip-style master link.

Why it exists: Predates derailleurs entirely. With one sprocket there is no reason to make the chain thin, so the original wide dimension survived for strength and cheapness.

Typically found on: BMX, track/fixie, kids' bikes, many commuter bikes with internal-gear hubs

Also called: 3/32 inch, 2.4 mm internal

Nominal 3/32" (2.38 mm) internal width, narrowing to about 2.18 mm on 9-speed and up; 1/2" pitch

The umbrella family for all chains that shift across a multi-sprocket cassette with a derailleur. Within the family, external width shrinks with each added speed while internal width stays close to constant, which is why sprocket tooth thickness has changed far less than sprocket spacing over the years.

Why it exists: Derailleur drivetrains needed a chain narrow enough to sit between adjacent sprockets and flexible enough to be pushed sideways from one to the next.

Typically found on: Every derailleur-equipped road, gravel, mountain, and hybrid bike

Also called: HG chain, IG chain

About 7.1-7.3 mm external, 2.38 mm internal

One chain width serves 6-, 7-, and 8-speed cassettes and freewheels because their sprocket spacing is nearly identical. These are the most interchangeable derailleur chains: any brand's 6/7/8-speed chain works on any brand's 6/7/8-speed drivetrain, and they remain in production because millions of commuter and entry-level bikes use them.

Why it exists: The mature form of the 'friction era' chain, standardized around Shimano's Hyperglide cassettes in the late 1980s before the narrowing race began.

Typically found on: Commuters, hybrids, older MTBs and road bikes, entry-level new bikes, many hub-motor e-bikes

Also called: CN-HG93 class

About 6.5-6.8 mm external, roughly 2.18 mm internal

The first step in the narrowing race. Nine-speed chains from Shimano, SRAM, KMC, and Wippermann interchange freely in practice. Still common on mid-1990s to mid-2000s road and mountain bikes and on current budget and touring groupsets.

Why it exists: Adding a ninth sprocket to the same freehub body forced tighter sprocket spacing and a thinner chain.

Typically found on: MTB and road bikes ~1997-2005, current entry-level and touring drivetrains, many e-bikes

Also called: CN-4601 class, narrow 10s

About 5.9-6.2 mm external, ~2.18 mm internal

Ten-speed chains are slightly asymmetric in some brands (Shimano road 10s chains are directional in shape though not marked for the rider). Cross-brand interchange generally works: KMC, SRAM, and Shimano 10-speed chains all run acceptably on each other's 10-speed drivetrains, though shifting is crispest with the matching brand.

Why it exists: Continuation of the sprocket-count race on road (2005+) and MTB (2010+, SRAM's original 1x11 precursor 'Dynasys' era for Shimano).

Typically found on: Road bikes ~2006-2012, MTB ~2011-2015, current mid-range gravel/commuter and many e-bike drivetrains

Also called: CN-HG601/701/901 class

About 5.5-5.6 mm external, ~2.18 mm internal

The dominant road standard from 2013 to 2021 and MTB standard 2014-2018. Shimano and SRAM 11-speed chains are widely used interchangeably, and KMC/Wippermann/YBN sell single 11-speed models advertised for all brands. Campagnolo 11-speed prefers its own chain but third-party 11s chains labeled Campy-compatible work.

Why it exists: Eleventh sprocket added on a slightly wider road freehub body; MTB followed with wide-range 1x11 cassettes (SRAM XX1, 10-42T).

Typically found on: Road bikes 2013-2021, MTB 2014-2018, current Shimano 105/GRX-class bikes, many e-bikes

Also called: HG+ chain, Eagle chain, CN-M9100 class

About 5.25-5.3 mm external, ~2.18 mm internal; standard roller-chain profile

The mainstream 12-speed chain shape used by Shimano (road and MTB) and SRAM Eagle (MTB). Shimano's Hyperglide+ chains have asymmetric plate shaping and are directional: the printed logo must face away from the frame. SRAM Eagle chains are their own optimized design but share the conventional profile, and aftermarket 12-speed chains from KMC, YBN, and Wippermann are sold to fit both Shimano 12s and SRAM Eagle.

Why it exists: Shimano shaped Hyperglide+ plates so the chain shifts under load in both directions; SRAM designed Eagle around huge 10-50/10-52T cassettes.

Typically found on: Nearly all current mid-to-high-end MTBs, Shimano 12-speed road bikes (105/Ultegra/Dura-Ace Di2), most current mid-drive e-MTBs

Also called: Flat Top, road 12/13-speed AXS chain

Narrower than standard 12s with flat-profiled top on the outer plates; oversized rollers; only fits Flattop-specific cassettes/chainrings

SRAM's 12-speed road AXS groups (Red, Force, Rival, Apex) and 13-speed XPLR use a visibly different chain: the outer plates have a flattened top edge and the rollers are slightly larger in diameter. It is a closed standard: Flattop chains require Flattop cassettes, chainrings, quick links, and chain tools, and are not compatible with SRAM Eagle MTB drivetrains or with Shimano 12-speed parts. SRAM Eagle 'Transmission' T-Type MTB groups use their own distinct Flattop-style chain as well.

Why it exists: SRAM claims the flat-top profile adds strength and quiet running in a narrower chain, enabling its 10-tooth-small-cog road cassettes.

Typically found on: SRAM AXS road and gravel bikes (Red/Force/Rival/Apex AXS, XPLR), SRAM T-Type e-MTB and MTB transmissions (MTB variant)

Also called: Ekar chain, XPLR 13s

About 4.9-5.25 mm external depending on brand

The newest niche. Campagnolo Ekar (gravel, 2020) uses its own ultra-narrow 13-speed chain; SRAM's 13-speed XPLR AXS (2024) uses the road Flattop chain; Rotor and some hub-drive systems also offer 13-speed. There is no shared 13-speed chain standard, so match the chain to the exact groupset.

Why it exists: One more sprocket for wide-range 1x gravel drivetrains without a front derailleur.

Typically found on: Campagnolo Ekar gravel bikes, SRAM Red XPLR 13s gravel bikes, Rotor 1x13

Also called: eBike chain, KMC e-series, reinforced chain

Same speed-specific widths as regular chains; reinforced plates and pins

Not a different size but a different duty rating. E-bike chains such as KMC's e8-e12 series keep normal 8/9/10/11/12-speed dimensions so they fit standard cassettes, but use thicker or harder plates, stronger pin riveting, and higher tensile strength to survive mid-drive motors, which multiply pedaling torque through the chain and shift under power. Marketed as compatible with Bosch, Brose, Yamaha, and Shimano STEPS systems.

Why it exists: Mid-drive motors put motor torque plus rider torque through the chain, and shifting under that combined load snaps or rapidly wears standard chains.

Typically found on: Mid-drive e-bikes (Bosch, Shimano STEPS, Brose, Yamaha); recommended for any e-MTB or e-cargo bike

Also called: master link, PowerLock, PowerLink, MissingLink, Connex Link, SM-CN900

Speed-specific: a quick link's plate thickness and width must match the chain's speed (an 11s link does not fit a 12s chain, and Flattop links fit only Flattop chains)

Two ways to close a derailleur chain. A quick link (master link) is a special two-piece outer link that snaps together by hand or with pliers; a connecting pin (Shimano's traditional method) is a guided rivet pressed in with a chain tool. Quick links are now the norm for all brands at 11-13 speeds. Reuse rules differ sharply by brand: Shimano and SRAM officially state their 11/12-speed quick links are single-use, KMC's MissingLink is sold in reusable and non-reusable versions, and Wippermann's Connex Link is fully reusable by hand with no tools.

Why it exists: As chains narrowed, field repair and cleaning removal by chain tool became riskier (pressing pins weakens narrow plates), so snap-together links replaced them.

Typically found on: All modern derailleur chains; 1/8" chains use simpler clip-style master links

By counting rear sprockets

Count the sprockets (cogs) on your rear cassette: that number is your chain speed. 12 sprockets means a 12-speed chain, 11 means 11-speed, and so on. If the bike has only one rear sprocket and no derailleur, you likely need a 1/8" single-speed chain (though some single-speed conversions use 3/32").

By markings

Look at the outer plates for stamped or etched text. Shimano chains carry a CN- model code (e.g. CN-M8100 = 12-speed); SRAM chains say Eagle, Flattop, or PC-xxxx; KMC stamps the series (X11, X12, e12). Search the code online to get the exact speed. A visibly flat upper edge on the plates means a SRAM Flattop chain. An arrow on the quick link shows required drive direction.

By measuring

With calipers, measure across the chain at a pin (external width): about 9 mm is 1/8" single-speed; ~7.1 mm is 6/7/8-speed; ~6.6 mm is 9-speed; ~5.9 mm is 10-speed; ~5.5 mm is 11-speed; ~5.25 mm is 12-speed. Pitch is always 1/2", so also verify wear: with a 12" ruler, pin 0 to pin 24 should measure exactly 12"; more than 1/16" over means replace.

By drivetrain brand and groupset

If you know your groupset (e.g. Shimano Deore 12s, SRAM Rival AXS, SRAM GX Eagle), the chain family follows: Shimano 12s uses Hyperglide+; SRAM road/gravel AXS uses Flattop; SRAM Eagle MTB uses Eagle. For anything 11-speed or below, any reputable chain of the matching speed count will work.