https://si.shimano.com/pdfs/dm/DM-MARD001-00-ENG.pdf

Shimano's instructions show this step being done without the chain installed. Also, are you sure chain length is correct? Looks kinda short.

 

Is the derailleur hanger bolt seated? Loosen bolt, tension de against hanger and retighten.

 

I was looking at the instructions for the right chain length maybe it was cut to short. I guess shimano doesn't have the pins to rejoin chains anymore.

 

I guess shimano doesn't have the pins to rejoin chains anymore.

No. They were always a poor system, anyway. Long before Shimano stopped using them, I began using other companies' quick links on my Shimano chains because they're simply better.

 

Chain length was right. If i add more chain its going to be to long.

Pilsner1 i have looked and its flush with the derailleur mount tab.

 

That looks like it might be too short. My Yeti with XT 12 spd came from seller set up too short. I didn't think anything of it because I used to set up with chain as short as possible with derailleur really stretched at lowest gear. But it was having chain drop on biggest cog, and I couldn't get that B adjust to match the line. Turns out there was two problems. One was they had installed the derailleur wrong, theres that little piece that rotates and has a little additional tab for the B screw was not in position. The B screw was instead hitting directly on the frame hanger tab. Fixed that and still couldn't get the tension to match the mark. Then checked chain length, I ended replacing chain and making it on the long side. In the highest gear (smallest cog) my chain is 4mm away from the rubber bumper near the upper pivot of the cage. Yours still has lots of space. I wasn't used to this, but that's why they put that bumper there. Afterr that, no problems, shifts great.
https://forums.mtbr.com/attachment.php?attachmentid=1323115&stc=1

 

You have the derailleur installed wrong. The tab that I have circled goes on the other side of the hanger so that the B-gap screw tightens against it. Taroroot mentioned this earlier for you to check.

That looks like it might be too short. My Yeti with XT 12 spd came from seller set up too short. I didn't think anything of it because I used to set up with chain as short as possible with derailleur really stretched at lowest gear. But it was having chain drop on biggest cog, and I couldn't get that B adjust to match the line. Turns out there was two problems. One was they had installed the derailleur wrong, theres that little piece that rotates and has a little additional tab for the B screw was not in position. The B screw was instead hitting directly on the frame hanger tab. Fixed that and still couldn't get the tension to match the mark. Then checked chain length, I ended replacing chain and making it on the long side. In the highest gear (smallest cog) my chain is 4mm away from the rubber bumper near the upper pivot of the cage. Yours still has lots of space. I wasn't used to this, but that's why they put that bumper there. Afterr that, no problems, shifts great.

 

Chain pins are long gone.

You need a Quick Link which should come with the chain.

 

Is this a new set-up on the bike? Assuming it is, do you have the correct derailleur hanger on the bike? If you had a direct mount derailleur previously and are now mounting a standard mount derailleur on the direct mount hanger, the derailleur will be too far away from the axle. Both of my bikes with Shimano 12-spd have the derailleur mount closer to the axle than what your bike is.

https://wheelsmfg.com/blog/standard-mount-vs-direct-mount-derailleur-hangers.html

 

I have a Dartmoor Primal 29. I don't think it even has a option for a direct mount derailleur hanger.

 

So this is going to be a dumb question , but how do i create a post? I can't find anything that says create.

 

Back out of the thread, and you'll see the +Post New Thread button

 

I added some more chain length which let me hit the 51 tooth mark on the derailleur. But the chain is too long when in the 10tooth cog. So what the problem is with the derailleur tabs mount in the wrong position. So how did i fix this you say. Easy don't use the shimano b tension stop. Doesn't look the greatest but everything works fine.

I really like how this build came together even though the bike had so many problems from the get go.

Thanks everyone for your help.

 

I sent Dartmoor an email about the problem the other day. They probably won't have a clue what i'm talking about. Oh well The problem is the way the rear derailleur hanger is coming out so much an angle for the rear wheel to slide in. Most rear derailleur hangers go straight down. So they could easily fix this buy cutting the tab back. Or just have it setup the ghetto way. Everything works fine. Still lines up on the 51 tooth line after a few hours of riding.

 

Transition had to create a new hanger because the Shimano 12s was having problems, I'm guessing this is the same.

 

Found this thread as was having the same issues plus backpedal chain drop. Took a stab at trimming/filing down some pieces. Filed down the derailleur stopper plate and my hanger. Seems to be a lot better and can adjust to the point the derailleur is too close to the cassette. My frame is a 2019 Chromag Wideangle. Happy to note the trimmed bits are not showing any unexpected fatigue or wear. Mind you my bike is a hardtail and the derailleurs move much more on a full-suspension bike due to the rear leverage.

To remove the stopper plate you will need to remove the C Ring - see snippet below I grabbed from Shimano's Manual:

Stopper plate trimmed
View attachment 1945390

Hanger Trimming

 

Im having exactly the same issue on a 2023 Trek Slash. When I rotate the tab out of the way and the b tension screw sits directly on the hanger I can get my indexing perfect.