Wrong derailleur for that cassette. Look up the max cassette size for it and get that size.
nforrest on
It looks okay from here but I’d suggest looking at the B gap before making any changes. If it’s from the factory/bike shop like this, I’m inclined to think it’s right but if it’s giving you trouble, you could take it back, describe the issue, and ask the shop to look at the chain length and derailleur adjustments.
Worst-case, you could add a small chain guide that would keep it from coming off the chainring.
If you didn’t get one with your bike, get a b gap tool for AXS.
Lastly, check the derailleur hanger with a hanger tool.
How do you transport the bike? Could the rear derailleur have taken a whack during transport?
TG__Goose on
use the sram b-gap tool to check its set correctly.. on XPLR you measure this on the 2nd largest cog. it should be a 7-8mm measured gap on the tool.
If thats a 42 tooth front chainring, you should probably have 112 links on a Crux frame with a 10-44 cassette. No matter what a calculator says, measure the chain in the big/big combo without routing thru the derailleur. add two sets of links past where they meet for 1x systems.
If the jockey wheel is too close to the biggest cog.
Go to the lowest gear 11t. Shift to the next one and pull up your bike and spin slowly the crank. If you hear something grinding you need to tight b screw and correct limit screws and cable tension.
If nothing happens it’s probably a chainline. You’ll need a front derailleur and two chainring crank. But that must be done by an experienced bike shop so he can figure out what size in mm you’ll need.
12 speed cog and one chainring will perform really bad if the chainline is off. 12 sp and two chainring the chainline are the way to go in my opinion.
Edit I read that the chain falls from chainring.
it looks like the previous owner broke front derraliour and added a single chainring without changing bb and axle length.
You could go for new bi-plate, chain and shifter or chain guide like the fellow biker suggested.
7 Comments
Dropping from chainring?
Wrong derailleur for that cassette. Look up the max cassette size for it and get that size.
It looks okay from here but I’d suggest looking at the B gap before making any changes. If it’s from the factory/bike shop like this, I’m inclined to think it’s right but if it’s giving you trouble, you could take it back, describe the issue, and ask the shop to look at the chain length and derailleur adjustments.
Worst-case, you could add a small chain guide that would keep it from coming off the chainring.
Yeah, it looks a link too long to me.
This would be an easy chain guide to run though.
https://www.wolftoothcomponents.com/collections/gnarwolf-chainguides/products/gnarwolf-chainguide-braze-on-mount-rev2
https://www.performancebike.com/specialized-aethos-crux-front-derailleur-mount-w-hardware-s201900005/p1269972?srsltid=AfmBOoocHngsRMXY11B-WcyR9lSUxR21vufCqBFXZ3tZ6pXUH6FXS3lr
Is it an XPLR Rear Derailleur?
If you didn’t get one with your bike, get a b gap tool for AXS.
Lastly, check the derailleur hanger with a hanger tool.
How do you transport the bike? Could the rear derailleur have taken a whack during transport?
use the sram b-gap tool to check its set correctly.. on XPLR you measure this on the 2nd largest cog. it should be a 7-8mm measured gap on the tool.
If thats a 42 tooth front chainring, you should probably have 112 links on a Crux frame with a 10-44 cassette. No matter what a calculator says, measure the chain in the big/big combo without routing thru the derailleur. add two sets of links past where they meet for 1x systems.
[https://docs.sram.com/en-US/publications/2bJvdvYz3DCAfCZVNeUucG/UM%20-%20eTap%20AXS?models=rd-riv1-e-d1#hashItem=chain-installation](https://docs.sram.com/en-US/publications/2bJvdvYz3DCAfCZVNeUucG/UM%20-%20eTap%20AXS?models=rd-riv1-e-d1#hashItem=chain-installation)
If the jockey wheel is too close to the biggest cog.
Go to the lowest gear 11t. Shift to the next one and pull up your bike and spin slowly the crank. If you hear something grinding you need to tight b screw and correct limit screws and cable tension.
If nothing happens it’s probably a chainline. You’ll need a front derailleur and two chainring crank. But that must be done by an experienced bike shop so he can figure out what size in mm you’ll need.
12 speed cog and one chainring will perform really bad if the chainline is off. 12 sp and two chainring the chainline are the way to go in my opinion.
Edit I read that the chain falls from chainring.
it looks like the previous owner broke front derraliour and added a single chainring without changing bb and axle length.
You could go for new bi-plate, chain and shifter or chain guide like the fellow biker suggested.