Ultegra RD-8050 convert SS to GS

[zvucetic]

Hi,

I'm just checkin the option to convert di2 short cage to medium.

I was checking difference in parts for the two derailleurs:
http://www.sjscycles.com/Drawings/Shima ... ch_Doc.pdf
http://www.sjscycles.com/Drawings/Shima ... ch_Doc.pdf

Seems that the only difference is in the two plates (inner/outer).

Has anyone tried this, what are your experiences?

[Klaster_1]

What's your goal? Do you plan to go 1x or use existing RD with wide range cassette? As far as I know, SS and GS have varying main parallelogram geometry to accommodate ramp angle difference between tight and wide range cassettes. Cage length only affects chain capacity. When you compare outer plates from diagrams, the cage rotation limit pin (beneath cage pivot axle) locations don't match, this might be an issue.

[zvucetic]

My goal is to mount the 11-34 cassete in case of hilly routes (or at least 11-32)
Are the ramp angles quite different in this 11-34 case?

[zvucetic]

Short cage 8050 doesen't exist, only medium (RD-R8050-SS) and long (RD-R8050-GS).

You only need Y3HR00040 and Y3HR98060 references.

so it's only up to chain capacity for the bigger cassete?

[Klaster_1]

.

[2lo8]

I'm pretty sure the parallelogram geometry is different between SS and GS because shadow RDs are only single pivot. Changing the cage will increase chain wrap capacity, but the slope of the slant is meant to track narrow range cassettes instead of wide.

[alcatraz]

Short answer: You can't clear larger cogs by swapping the cage.

You can only increase chain wrap capacity.

If you only need a little bit more chain wrap capacity you can oversize pulley wheels. You can get a roadlink to clear big cogs but you'll sacrifice shift quality unless you run something like a 14-34t cassette.

If shift quality is important then use the appropriate size derailleur. If you don't use the cassette often just hunt for a 2nd hand ultegra 6800 derailleur. They aren't as expensive.

[ooo]

Shimano do not have "medium" cage in catalog, actual abbreviations meaning:
. . . . . short cage = . SS
. . . . .. long cage = . GS
super long cage = SGS

This will explain why changing cage will not improve shifting on cassettes that was not recomended for rd with stock cage:
Difference of GS and SS road RD (example: RD-6870 GS vs SS, photo by handsonbike):

[2lo8]

Shimano doesn't use short/medium/long cage consistently in their English language materials. They have called GS derailers short (when only GS/SGS), medium (and mid) and long (traditional catalog and tech doc usage) in various official Shimano materials. There's very little point bickering about the "right" way of calling a long/mid cage RD when it is obvious what is meant is GS because Shimano themselves are very bad at it, although I beleive that Shimano is trying to move from short/long/superlong to short/medium(mid)/long for "vernacular" and marketing usage.

The only thing shimano can seem to agree on is SS is not midcage, even though some people want to call it that since it can handle bigger cassettes than it used to.

All from the Shimano website:

RD-M9100-GS
- Short cage derailleur
- 45T max cog size
- Works with both 11-speed and 12-speed 10-45-tooth cassettes
- Better ground clearance (28mm shorter cage)

The medium cage 11-speed rear derailleurs (RD-M7000-11-GS)

The XTR RD-M9000 is available in GS (mid cage)

ULTEGRA Rear Derailleur (11-speed). RD-6800 (SS/GS) Short Cage/Long Cage

[kofsw4]

I looked into swapping just the cage on my 6870 RD to be able to use larger cogs a while ago. In the end I got a good deal on a new GS derailleur and sold my old one on eBay. Cost me £30 and probably saved a lot of hassle, poor shifting etc

[zvucetic]

seems that it's not only the plates



But if the SS goes up to 11-30, 11-32 should fit with the b screw all the way?

[alcatraz]

The derailleur's "swing" angle is fixed, and it's different for each version.

The b-screw can help you to clear the cassette but it won't change the angle.

The manufacturer can specify a range like 23-30t support but only one cassette size will fit optimally (probably somewhrere in the middle of thr range). The further you stray from this optimal size, the less consistent will your shifting be.

I'm not advising against it. It works well enough for many people. I'm just trying to explain what exactly it is you are sacrificing by mismatching.

Short answer, 32t works fine on the short cage 7000/8000/9100 derailleurs. Is it a good setup? Depends how you ride and how picky you are. Not for racing.

[Billiano]

I do own a Di2 RD-8050 GS rear derailleur.

1. Converting from GS to SS
I got some cage plates fron Durace 9150.It is not possible for me to get them work.
The reason is when you try to convert from GS to SS the stop screw that exists on the cage is stopping to a block.

In GS case the stopping block is wider so does not allow to the cage to rotate that much in order to be retracted that much.
In SS cage the block is narrower so it retracts more.
The remedy is to Dremel cut the block and make it smaller.
It is an easy job.

2. Converting from SS to GS
It is possible ,but when the cage is fully retracted the lower pulley will be touching the derailleur.

Thats because GS is bqanana shaped while SS is Straight.

[hlvd]

Hi, I tried this with the previous generation 6870 and found it didn't work.

The derailleur body geometry is different and just changing the cage doesn't give anymore clearance for a larger cassette.

In the end I sold my SS derailleur and got a GS, worked perfectly.

[Billiano]

The swing angle is fixed as mentioned above. The GS has narrower angle due to and extra piece(block) fixed which limits swing.
While SS has only the block which slides the spring's end.

I am looking to transform GS to SS.
Has anyone done it?
The following Pics are from GS.
I would like a clearer Pic for the SS one.
To see if I can do the little surgery.

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