Supreme DH Chainline issue

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Supreme DH Chainline issue
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flag rallyimprezive
Posted: Dec 11, 2021 at 13:41 Quote
Hello there!
I have a Commencal Surpreme DH 27 v4.3. I just purchased it used. I noticed while trying to dial in the shifting that on the lowest cog (smallest) in the rear, the chainline appears to be way off. The chain jumps on the derailleur's jockey wheel. I switched to a brand new Zee derailleur that I had and the issue persisted. So at this point I think its one of two things:
- chainline is wrong
- derailleur hanger is bent

The hanger doesnt *look* bent, so I measured the chainline from the center of the bb to the chainring and its about 62.5mm, which doesnt seem right. The chainring is a SRAM directmount xsync2 with a 6mm offset. The crank is the SRAM Descendant DH. I cant tell if this is right or not, and honestly this is where I start to get overwhelmed because there are just so many different hubs, BBs, chainring offsets, etc.

Could the crank and chain ring have been installed so wrong that it caused the chainline to be that far off? What is the right chainline? Is a 6mm offset chainring the right one?

HALP!

Thanks in advance!
flag Knollyp
Posted: Dec 15, 2021 at 20:03 Quote
I’m no pro but a few things that come to mind are , is the spacer on the hub driver behind the cassette? Maybe the spacers on the bb were put on in the wrong orientation? Is the chain guide not spaced correctly? Happy riding!
flag Knollyp
Posted: Dec 15, 2021 at 20:06 Quote
I see you are also in Colorado worst case scenario head down to the Golden Commencal shop and they would definitely help get it right !
flag brianhcm1
Posted: Jan 9, 2022 at 8:59 Quote
rallyimprezive wrote:
Hello there!
I have a Commencal Surpreme DH 27 v4.3. I just purchased it used. I noticed while trying to dial in the shifting that on the lowest cog (smallest) in the rear, the chainline appears to be way off. The chain jumps on the derailleur's jockey wheel. I switched to a brand new Zee derailleur that I had and the issue persisted. So at this point I think its one of two things:
- chainline is wrong
- derailleur hanger is bent

The hanger doesnt *look* bent, so I measured the chainline from the center of the bb to the chainring and its about 62.5mm, which doesnt seem right. The chainring is a SRAM directmount xsync2 with a 6mm offset. The crank is the SRAM Descendant DH. I cant tell if this is right or not, and honestly this is where I start to get overwhelmed because there are just so many different hubs, BBs, chainring offsets, etc.

Could the crank and chain ring have been installed so wrong that it caused the chainline to be that far off? What is the right chainline? Is a 6mm offset chainring the right one?

HALP!

Thanks in advance!

I have a 20/21 Supreme that i bought used too and had to switch to a 3mm offset chainring to get the chainline correct. It came with a 6mm offset which is OEM for the DH crankset, but its not correct for this bike.
flag HendersonMike
Posted: Jun 20, 2023 at 19:46 Quote
rallyimprezive wrote:
Hello there!
I have a Commencal Surpreme DH 27 v4.3. I just purchased it used. I noticed while trying to dial in the shifting that on the lowest cog (smallest) in the rear, the chainline appears to be way off. The chain jumps on the derailleur's jockey wheel. I switched to a brand new Zee derailleur that I had and the issue persisted. So at this point I think its one of two things:
- chainline is wrong
- derailleur hanger is bent

The hanger doesnt *look* bent, so I measured the chainline from the center of the bb to the chainring and its about 62.5mm, which doesnt seem right. The chainring is a SRAM directmount xsync2 with a 6mm offset. The crank is the SRAM Descendant DH. I cant tell if this is right or not, and honestly this is where I start to get overwhelmed because there are just so many different hubs, BBs, chainring offsets, etc.

Could the crank and chain ring have been installed so wrong that it caused the chainline to be that far off? What is the right chainline? Is a 6mm offset chainring the right one?

HALP!

Thanks in advance!

[Edit again after re-reading your post]

I think your Chainline is off. Both my Shimano DH cranksets work perfectly on both my Commencals.

I have a 2020 Commencal Furious, and a 2022 Commencal Supreme DH, both have a 107mm shell width, and both are using the same Shimano PF BB, and both are running Shimano 83mm DH cranks.

The Furious has the Saints, and Supreme has the Zees, both cranks appear to have ZERO offset, and Chainline for both Cranks (with Factory Ring) is listed at 57.9mm.

Both cranks are flawless in their shifting, I can go into the highest or lowest gear without issues. I am even running 11-speed on both bikes and and have a 10-42 cassette on both bikes! LOL
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