Dura Ace - Ultegra Upgrade?

geoffub

I have a Dura Ace R9000 Di2 rear derailleur which is limited to 28T rear sprocket. As planning a 'hilly holiday' this summer, thinking of upgrading to 32T or even 34T on the rear cassette.
Looks like the Dura Ace R9100 & 9200's are limited to 30T so only option would appear to go Ultegra Di2 rear mech and that would allow 32/34T?
1. Is it technically possible to mix and match an Ultegra rear mech when everything else is Dura Ace.
2. Has anyone tried a larger cassette on a 9000 unit than 28T?

johngti

1. Yes
2. Not sure. I believe a 30 would work, might be pushing it with 32+

BetterShifting_Terry

Yeah.. 30 would work. I wouldn't try 32+, but that's up to you

The Ultegra RD-R8050-SS max is 30T, so you can get away with 32T if you really want to.
The RD-R8050-GS max is 34T, which is probably what you want .

Keep in mind that you can only use derailleurs from the same category and same speeds.

So: any derailleurs you install must be 11-speed, and must be a road or GRX derailleur
(No MTB derailleurs - M8050 / M9050).

These would all work:

• RD-6870-GS (max 32T)
  
• RD-9070 (what you have right now)
  
• RD-R8050-GS (max 34T)
  
• RD-R9150 (max 30T, so not ideal)
  
• RD-RX805 (Ultegra with clutch, released before GRX existed, I wouldn't. 34T max)
  
• RD-RX815 (GRX, with clutch. 34T max)
  

What wouldn't work: RD-M8050/RD-M9050 (MTB), RD-R8150 (12 speed), RD-R9250 (12 speed)

geoffub

Thanks guys,
I was looking I suppose at (but open to alternatives) the RD R8050 medium cage which Shimano themselves suggest a 34T is suitable. I agree the short cage version does not have sufficient capacity.
On the assumption Shimano quote 28T max for the DA 9000 rightly or wrongly I am hoping the R8050 would easily cope with a 34T max as quoted by Shimano?

super_davo

A left field option would be to buy a oversized pulley wheel; that will increase the range without buying a whole new mech.

Doesn't need to be Ceramic Speed - there are plenty of cheap one of AliExpress (see https://www.aliexpress.com/item/1005003786990283.html, but there are many others).

The "ceramic bearings" in them are rubbish because they are essentially unsealed, but they can be changed, and I am sure they would survive the holiday as is.

If you go that route, you can get chain + pulley + cassette and still have change from what you would have had to pay for the mech alone (plus I think it looks better).

geoffub

A left field option would be to buy a oversized pulley wheel; that will increase the range.

Not sure I follow how oversized jockey wheels increase the range? What range?
A 52T chain ring to a 26T rear sprocket is still a 2:1 ratio irrespective of size of jockey wheels.

Mad_Malx

geoffub said:

A left field option would be to buy a oversized pulley wheel; that will increase the range.

Not sure I follow how oversized jockey wheels increase the range? What range?
A 52T chain ring to a 26T rear sprocket is still a 2:1 ratio irrespective of size of jockey wheels.

The oversize jockey wheel has the same effect as lengthening the cage, so it can take up more chain slack. That means the range of the cassette ( tooth difference between small and big cog) can be larger without having a floppy chain on the small cog.
It doesn’t affect the derailleur ramp angle though, so doesn’t work quite as well l as a derailleur designed for a larger cassette range. Whether that is important or not probably depends on your specific set up and your perception.

geoffub

Thanks Mad_Malx, I can now see what Super Davo meant.

Is this something that someone else has tried with a Dura Ace Di2 9000 rear mech? and what range of cassette works?

super_davo

Mad_Malx said:

geoffub said:

A left field option would be to buy a oversized pulley wheel; that will increase the range.

Not sure I follow how oversized jockey wheels increase the range? What range?
A 52T chain ring to a 26T rear sprocket is still a 2:1 ratio irrespective of size of jockey wheels.

The oversize jockey wheel has the same effect as lengthening the cage, so it can take up more chain slack. That means the range of the cassette ( tooth difference between small and big cog) can be larger without having a floppy chain on the small cog.
It doesn’t affect the derailleur ramp angle though, so doesn’t work quite as well l as a derailleur designed for a larger cassette range. Whether that is important or not probably depends on your specific set up and your perception.

Exactly right on all counts. Seeing as Geofffub was only talking about a minor increase in size over the current 28T max then it is not being pushed too far out of spec, the small increase in length should be enough to give that bit extra.

Shimano are notoriously conservative with their spec limits. I can run my 6800 series Ultegra (which is same gen / max capacity) on 11- 30T just by loosening the B screw a bit. You might even by able to do that on your current mech as is. If I wanted to run 11-32 it wouldn't take much of an increase in cage length to give that extra range. However it is worth noting that it isn't just the mech you need to consider, it's also the frame and how it positions the mech - what works for my frame won't necessarily work the same on yours (though Wolftooth extenders could fix that).

Acknowledge the point about ramp angles - this would not be a total "run whatever size cassette you want" solution - more a temporary "run something larger than normal for a holiday" solution that's a fair bit cheaper.