It's not my photo, btw, I just googled "Shimano RD-R8000 cable outer" image search and found it on the 4th post on this page:
https://www.bikeradar.com/forums/viewtopic.php?t=13083407
... which looks about right to me.
I think my mech is the same angle as the one played by Pierre. It’s fixed by the tabs on the mech againstes the tab on the mech hanger on the frame. I checked against the ones in the shop and it looks the same. I think an adjustment of the cable length to just a touch longer will get that to as good as possible. If that doesn’t get it perfect then I think the under bb routing needs some attention.
On most traditional (i.e. non-Shadow) rear mechs, a nice long cable loop is a good thing because it reduces the friction between the inner and outer cable that you'd get in a tight curve. The rear mech cable entry point pivots forwards and backwards as you change gears, so a big loop allows this to happen without causing extra friction.
On a Shadow-style rear mech like yours, joebristol, the design of the rear mech is different (it's been used on mountain bike rear mechs for years) and the cable entry point doesn't move as the derailleur pivots. So any cable route that minimises friction is good. If you've only got a short distance between the two cable stops, a section of cable outer that provides as near as possible to a smooth 90 degree curve would probably be best... or a big loop-the-loop that does 270 degrees!
Probably need a couple of cm longer rear outer in that case.
Did you ever resolve this?
I am having issues on my CAAD12 with rear shifting. New cables, new outers but where the ferrule enters the right hand side of the frame the cable catches (have tried running just cable through and still happens).
Is it a CAAD12 with a shadow style mech? I have to use a really small loop on mine (like a 5cm length) to get it to shift smoothly. And with the really soft shimano outer
Roller plus 1
I regularly move my old Avid Rollamajigs onto new bikes. NOS if you’re lucky or that JTEK further up.
NOS Rollamajig still on eBay.
Half the price of the JTEK.
I got it working acceptably in the end - with cable length like Pierre’s photo above. Where you say rubbing do you mean it’s not sitting straight in the end of the frame?
I’ve actually gone to Ultegra Di2 now which wasn’t without some initial setup/ teething problems but it’s absolutely brilliant now.
