RD8000 Ultegra on Cannondale synapse HiMod.
The hanger on the Synapse has one notch, and the RD has 2 notches.
I assume that the one notch on the hanger should be in between the 2 RD notches.
A friends same bike and RD has the hanger notch above the upper DR notch setup by the LBS.
Both bikes shift well.
I assume the hanger notch should be in between the DR notches.

Am I correct. Pls advise.

From the Shimano dealers manual for install on common dropouts. Don't know if your frame has an unusual rear derailleur hanger.



Shimano rear derailleurs are designed for dropout of the following frame requirements. Let us know if you have another style.

Thanks for the detailed info.
In my case, in the "inner side" diagram the point "z" is in between the 2 protrusion of the DR.
Show I remove the DR and re-installed it so that it matches the position on the dwg?

I'm not really familiar with this series of derailleur so don't know what affect the different positions of the protrusion makes.

It will change the position of the RD a little, and thus may make a difference in the capacity of the RD. I assume that the attached information from Shimano is based on their instructions.




If you are within those specs, I don't see any reason to not follow their instructions.

The RD that I am using is the RD-R8000-GS with a 34 cassette.
I removed the DR and turn it, and installed it per the dwg. The "z" contact area is small.
Since the DR got turn CW with this new position the distance from the end of the chain stay, where the cable gets inserted to the barrel adjust on the DR was shorten substantially.
The cable housing got reduced to about 10cm, and was quite difficult to install because of the short distance and the cable stiffness.
I tested the shifting on the bike stand and it performed well.
Tomorrow I'll take for a ride uphill to see the result. Usually, on the uphill is when it starts skipping if the adjustment is incorrect.
Thanks again for yr time.

The geometry of Shimano's newer generation shadow RDs results in a shorter distance, and potentially a tighter cable loop, between the RD and the chain stay. Shimano specifies a more flexible cable housing for this loop.

SHIMANO Shift Cable Housing for Rear Derailleur | SHIMANO BIKE-EU

In my limited experience, this more flexible housing is definitely necessary if the RD cable exits the frame at or next to the rear axle.

Let us know the result. Does it shift better, worst or the same?

Some people here may be interested in knowing if the position of the 'bracket' matters, especially since you are at the large cog limit. Riders seem to always be trying to exceed the largest cog limit these days.

I installed the RD-8000 together with the 34 tooth sprocket on Ultegra 6800 shifters a year ago.
I must of installed the RD in the correct position because I noticed how short the distance was between the end of the chain stay cable housing entrance to the barrel adjuster.
I had no problems shifting.
Recently, I replaced my old shifters with Ultegra 8000.
I removed the RD to check the hanger alignment which was ok.
When I re-installed the RD I must have inadvertently placed the butting surface on the hanger between the upper and lower RD notches.
In this position, the housing was longer.
I went for a ride did a couple of adjustments to the barrel adjuster, and all was well.
A riding friend with the same bike and RD had the setup as I originally had it.
That puzzled me so I posted the question.
When the reply came I re-installed the RD according to Shimano's dwg with the lower RD notch butting against the surface "z" on the hanger. I had a hard time installing the inflexible cable housing within such a short distance; I need to get some flexible cable housing.
Went for a ride did some minor adjustments and all was well.
Shimano indicated that there should be no gap on surface "z" because the gap could affect shifting.
I don't know how much the RD would rotate if tightened within specs.
Also, what is the upper RD notch for; a possible different setup.
I can't say the shifting was any different between the 2 setups, but maybe in the long run it would be.

I don't know what the upper RD notch (stopper) is for. There is no mention of it in Shimano manuals. The 'Shadow' style MTB RDs that I have seen doesn't have it. Also don't recall seeing any modern RD hangers that would use a stopper in that location.

As for the cable housing, the type mentioned in the other post above is the Shimano recommended one. Seems to be low compression coiled housing, similar construction to brake housing. Originally, in the 1980s, the SIS cables were also wound. This was before the SP40/41, linear strand was used.

As for the cable housing, the type mentioned in the other post above is the Shimano recommended one. Seems to be low compression coiled housing, similar construction to brake housing. Originally, in the 1980s, the SIS cables were also wound. This was before the SP40/41, linear strand was used.[/QUOTE]


I was able to locate the flexible cable housing OT-RS900 at LBS. I've already replaced the stiff one with the new one which was easy to install.

Tested the shifting on the stand, and everything looks ok.

Thanks for responding