Hi all
I have been riding with my kickr core and zwift cog for about half a year now. but suddenly today m it begins derailing and i simply cant figire out why… i have tried remounting and loosening it but nothing works
Does anyone know the cause of this
Thank you all in advance
Do you mean your chain is coming off the cog?
If so, make sure you are in the correct gear and make sure the cog offset is where it normally is. If either of these are “off”, yea the chain will pop off the cog.
Can you post a picture taken from directly behind the derailleur? If chain alignment is the problem, what you are seeking is a perfectly straight line from the Cog to the chain to the derailleur pulleys.
A worn chain can also jump off the Cog so you could check that as well, or take the whole mess to a bike mechanic for hands-on service.
As you can see the chain is already derailing here. its almost as if it forces itself of no matter what i try and how many times i put the chain back on
Frederik, it looks like the cog offset is too high for whichever front chainring you’re on. Adjust the offset down to 1 and then work your way up until your chain is lined up on the top, then adjust cassette gear until chain is lined up at the back.
If you don’t know how to adjust the cog offset, do this.
rotate the cog until you can see the little window on the left hand hub (left side of the chain when looking from the rear, the part with the little ears / bosses) and can see the number inside the window
Hold the right hand hub (part covering the orange cover)
While holding the right hand side still, turn the left side using the ears and watch the number in the window. You should hear a pop and see the number in the window change as it indexes between offset positions.
Keep turning the left hand side until it indexes back to 1 (it will wrap back around from 10), then work your way up through 2, 3, etc until the chain lines up, then adjust rear gear until derailleur is vertical.
If you ever change front chain rings, you will need to adjust the cog offset again.
It’s hard to see how it’s aligned from your photo since your camera is not directly behind the Cog and the chain is not on the Cog.
The condition of the chain makes me wonder how much mileage is on it and whether you have measured wear. SRAM recommends replacement of a 12 speed chain at 0.8% elongation so you need to understand if it is at or above that level. If you don’t have the tools to measure that, you should either take it to a bike shop or just put on a new chain.
The chain stays on now but its like it wont freeride anymore only when i loosen the bike but i cant ride on it like that
It looks like the adjustment is a little bit misaligned with the derailleur pulling the chain to the right. It doesn’t look really bad. This can be affected by my perspective on it, so having a mechanic look at the bike on the trainer would be a good idea, and they could also tell you if the chain is worn. It can be hard to understand this type of problem from pictures, but it’s usually easy to do it with the bike in front of you. You also need to have the drivetrain cleaned so you don’t wear it out faster.
Also I noticed in your previous picture that the quick release skewer is not closed properly. A bike shop could explain to you how that works. When it’s not closed properly there is the possibility of the bike separating from the trainer if you do a crazy sprint.
@Paul_Southworth is there also an end cap missing? It looks like the Cog is rubbing right against the derailleur hanger.
Can’t tell without a picture with the bike off or better angle 
Turns out i just was being stupid and using the wrong endcaps
I also had a bike mechanic check the chain and he said it wasnt anywhere near being worn out just needed a cleaning
But thanks all for the help
