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Discussion Starter · #1 ·
I'm mainly trying to find Shimano's specs on rear derailleur placement, probably in relation to the axle. Anyone know where to find such a thing? The rear derailleur can't be stuck just anywhere especially with 12 speed, but I'm not finding anything for manufacturers, just installation and adjustments.
 

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Discussion Starter · #4 ·
Is your setup anything different from this video at 5:00?

For anyone else, I have a post in Drivetrain about what I'm dealing with:



No, I'm set up just like that. But again, in that video the line is basically perpendicular or tangent to the teeth while mine is at an angle. To me this says something isn't right and the angle is different for some reason, like the chain length is wrong or the derailleur is allowing the chain to wrap more or less around the cassette than it should (don't have it in front of me to know which).

I've gone over Shimanos instructions a bunch and it's set up just like they say and like all these videos show so something else has to be off since everything is new and Shimano. The only thing that really makes sense is that the derailleur isn't exactly where it should be? At least I haven't come up with anything else. I'm about to go thru those Sram documents but I imagine Shimano is essentially the same since they showed up to the party late. I can't imagine that's it unless I somehow have a wrong hanger, but running out of ideas.

I'm new to 12 speed but I was a bike mechanic for quite a few years and usually can figure out what is wrong if I mess with it enough and was actually the guy people brought stuff to when someone else couldn't figure it out. But everything is much more precise now and the location and angles of everything really effects how it works and why the B screw adjustment is so critical. So I'm just going to walk away from it for a day or 2 and come back with fresh eyes but if anyone has suggestions I'm open to anything to try.
 

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From the top of my head, but am sure it’s quite easy to find the info from google.

Centre to centre axle to mech hanger bolt 32mm +/- 2mm
Horizontal distance (parallel to ground)
9mm +/- 1.5mm
And as an angle from hanger bolt to axle I THINK 25° no idea on tolerance. Do some trig from the other numbers to get a better idea on angle.
 

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Discussion Starter · #10 ·
Your response was not ignored and it was appreciated! I found out my hanger is out of spec by a good amount with your very helpful link to frame fitment specs - aka - frame building.

I also spent many years working in bike shops and racing and know how to adjust a derailleur. Which is also how I knew something was out of spec and why I asked the question, and asked it where frame building specs are relevant even if my intentions were not to build a frame.

I looked quite a bit for the info from Shimano since those are the parts I'm using, so your Sram document was very helpful!
 
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