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Ratio Ring – 12/13 speed, 5 Bolt 110 BCD


The 7075 aluminium Ratio Ring, machined by Ratio in the Lake District, was designed for the broadest possible compatibility; the teeth are narrow enough for Ekar™ 13 speed, but the tooth profile means the chainring can also handle SRAM Eagle™ and Flattop™ 12 speed chains. 40, 42 & 44t sizes are also compatible with Shimano HG+ 12 speed chains. The ring uses a standard 5 bolt 110 BCD fitment and features an offset tooth profile for improved chainline.

View our Support page here. For more information, check our compatibility guide.

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The Ratio Ring is the first aftermarket chainring option to be compatible with Campagnolo Ekar™ 13 speed chains, and features a tooth profile that can also be used with SRAM’s Flattop™ and Eagle™ 12 speed chains. 40, 42 & 44t sizes are also compatible with Shimano HG+ 12 speed chains.

We’ve designed an asymmetric tooth profile that allows one roller to react all the load from the slack side of the chain. This helps manage the disengagement of the chain even when it’s stretched, and secures the lower span of the chain while freewheeling over rough terrain – preventing the “wave” behaviour that can otherwise cause the chain to jump off the teeth. At the tight side, the narrow-wide profile ensures the chain engages smoothly during pedalling and a chamfered seating curve helps to clear debris.

The tooth profile is adapted to engage with SRAM’s 7.9 mm Flattop™ rollers without compromising the kinematics of standard 7.7 mm rollers.

Chainline – for all sizes except 34t the chainring tooth centreline is in line with the mounting face. This is the same chainline as SRAM and improves performance in the large sprockets of the cassette. Due to geometric constraints the 34t centreline is 0.8mm outboard of the mounting face. This isn’t enough to cause chainline issues and is less offset than the majority of aftermarket chainring options.

The Ratio Ring is designed and manufactured in the Lake District, UK from 7075 aluminium.

Weight: 34T – 43g, 36T – 52g, 38T – 69g, 40T – 72g, 42T – 82g, 44T – 89g

Bolts not included.

Weight 100 g
Dimensions 20 × 20 × 2 cm
Chainring Size

34T, 36T, 38T, 40T, 42T, 44T


To reduce waste we will send orders of over 10 units in bulk packaging rather than individual kit boxes. If you have ordered less than 10 kits but would also like to reduce the packaging of your bulk order or have any questions please email us at Equally if you would like the full packaging for orders of 10+ kits drop us a line too.

Large orders

If you wish to order more than 50 units please contact us directly via

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