Chainring offset. H...
 

Chainring offset. Help!

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Right, I need some help with chainring offsets please.

Want to put a shorter crank on my new Cotic Rocket Max, Cotic states: 

Chainline: 52mm Shimano / 53mm Boost chainline for up to 32t round/30t oval chainring,

I've seen a crankset that is either 50 or 53mm chainline and takes a Sram 3 bolt chainring, which most seem to be 3mm or 6mm offset.

From what I've read offset is inboard, so if I put a 3mm offset chainring on the crank set with 53mm chainline does that end up as 50mm and therefore NOT compatible with my bike?

Or can I put one on the 50mm CL crank backwards and get 53mm....

🤯


 
Posted : 14/05/2025 7:48 pm
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Typically, Shimano control offset with axle length.

Typically others have a standard crank and control offset with the ring. It's likely that the 53mm is a 3mm offset ring and the 50mm is a 6mm off set ring, both starting from the same place. However, SRAM can be a minefield and it can vary by bottom bracket type 


 
Posted : 14/05/2025 8:08 pm
Posts: 21632
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Typically, Shimano control offset with axle length.

Typically others have a standard crank and control offset with the ring. It's likely that the 53mm is a 3mm offset ring and the 50mm is a 6mm off set ring, both starting from the same place. However, SRAM can be a minefield and it can vary by bottom bracket type 


 
Posted : 14/05/2025 8:25 pm
 mboy
Posts: 12647
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What Onzadog says…

Though it always used to be that a 6mm offset ring gave 49mm chainline, a 3mm gave 52mm and a flat ring 55mm with SRAM… That is until they buggered around further outboard with the latest T-Type stuff chainline wise.

Shimano have typically changed the offset with a longer axle as previously stated, so you need to change cranks with Shimano to change the offset, but only need to change chainring with SRAM to change it…


 
Posted : 14/05/2025 8:36 pm
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Ah so if I bought the 53mm CL crankset and swapped the 32 tooth chainring it comes with for a 3mm offset 30 tooth it would remain a 53mm CL and be bang on the CL Cotic recommends?

Cool, think I get it now. Basically I don't want to spend a fortune at the moment and buy Hope 155 cranks, but have found some Cube own brand ones that come in 160mm for not much money, so fancy giving them a try for a while and see I get on.

Cheers both.


 
Posted : 14/05/2025 8:39 pm
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Very likely but the reason for liberal use of the term "typically" is because not everyone plays by the rules, sometimes not even their own rules


 
Posted : 14/05/2025 8:42 pm
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Cool, makes sense though so I might give it a go. Cranks are only £60.


 
Posted : 14/05/2025 8:48 pm