Tinkering 101: Shifting big gears with Shimano Dura-Ace 9100/9150 & Ultegra 8000/8050 Derailleurs

Shimano’s latest 11-speed Dura-Ace 9100 mechanical / 9150 Di2 rear derailleurs and their Ultegra cousins, the 8000 mechanical and 8050 Di2 – in the regular / short cage variant, are listed by Shimano as having a maximum rear cog capacity of 30 teeth. The mid-cage of the latest Ultegra derailleur, mechanical or Di2, is designed to work nicely with the company’s newest cassette addition, the 11-34 ratio.

But like a lot of manufacturers, Shimano is playing it safe. JOM of the Gravel Cyclist crew figured the short / regular cage versions of these derailleurs are capable of much more, so he produced a video about it.

Can you shift to a 36 tooth cog using Shimano’s latest lineup of 11-speed Dura-Ace / Ultegra short / regular cage rear derailleurs?

As an FYI, the Ultegra versions of these derailleurs will be all over gravel bikes from 2018 onwards.

Thank you to ROTOR America for supplying the 3d+ crankset and bottom bracket as seen in this video.

Thanks for watching!

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  1. Avatar David

    Do you think it would have managed that 11-36 with a 50/34?

    • Avatar old geezer

      Just put a 11/36 cassette on my road bike, with 34/50 crank. The Ultegra 6700 rear derailleur only needed a bit more set to the B screw, to keep the upper guide pulley from rubbing the largest inner cog.
      Know that this system shifts perfectly, AS LONG AS you are smart enough to NEVER shift big-to-big, i.e. 50 front onto the 36 rear, as there is not enough chain for this combo. Small -small isn’t an issue, it just maxs out the wrap / chain slack storing capacity of the rear cage arm.
      Touring riders have experimented with all sorts of gearing and shifting alternatives, for years, and once you understand why and how components function, you can decipher the limits and ways of compromising to gain more versatility, sometimes at the expense of a bit of smooth performance. MTB rear units used to work with road shifters, but the planned obsolescence foisting 1 x 12 or whatever also has changed systems so they are largely not compatible with older components, nor road with mountain. 1 x anything is arithmetically idiotic, as achieving a wide gear range involves huge gaps between gears that only freeriders or young macho bros can handle, if they ever ride uphill to begin with.

  2. Avatar Paul

    Just had my local guy install a rd r-8000 Ultegra I have an 11 X 36 cassette ( used the wolftooth link ) and it seems to work great so far, with a 46/34 on the front.
    Gravel Grovel will be the test in a few weeks.

  3. Avatar Tom in MN

    Can you repeat in text what you said at the end? It sounds like you said even the short cage version could handle the large cogs. But then the short cage would limit the chainring difference and how far you could crosschain, correct? But is there any reason to ever get the short cage instead of the midcage? Thanks for an interesting demo.

  4. Avatar stephen

    Interesting! Please let us know if any of these RDs work okay with an 11-40 cassette; I’ve had very poor shifting with the Roadlink and 5800GS so prefer to avoid it. FWIW, the 5800GS is fine with 11-36 (stock on Specialized’s Sequoia Elite), and can just handle 11-40 with the B-tension maxed out – on one bike at least. As the 5800GS/6800GS are dual-sprung rather than Shadow designs they ought to handle smaller cassettes like 12-25 better too, despite Shimano saying they’re for 28T+.

    A friend has set up a number of bikes with 5800/6800/9000 short cage RDs and 11-32 cassettes, so Shimano are quite conservative. I’ve also found the pre-Shadow MTB RDs shift well on road cassettes like 12-23 if the B-tension screw is relaxed.

    Surely it must be about time for a road-lever-compatible rear derailleur with a clutch from Shimano, and a subcompact crankset like 46×30 or smaller too…

  5. Avatar wheels

    I have Di2 6870 and Sram PG-1170, 11-36 (650b wheels) and Shimano 11-34 (700c wheels).
    I used roadlink a while, then i took it off.
    I preferred to run my RD drilled, so i could have higher tesnion, on the tension spring.
    This makes the pulley move closer to the cassette.
    My B-screw is not used at all.
    I am sure i could use a 11-38T cassette if they existed.

    Looking at JOM’s video, it seems the pulley run far from cassettes tooths (i might be wrong!?)
    But it looks like mine did when i used Roadlink.

    I would like to know what difference it is between Di2 8050 and 6870.
    Does 8050 offer any mechanical advantage?
    Shifting is really good at 6870.

    Also the shifters. Are the grip at hoods closer to rider (less reach) than 785 shifters?

    I also wonder about the FD cage on 8050 vs 6870.

    • Avatar stephen

      Agreed re 11-38; somebody should make one – or a conversion cog for the Sjimano 11-32 – just remove the 13 and add a 38. With 5800GS (equivalent to 68x0GS) and chain length set for 11-36, 11-40 works okay on the small ring but the top jockey wheel only barely clears the 40; there’s not enough chain to run the 40 with the big ring, not that I would.

      Dunno about the levers, sorry.

      I think the main difference with any Shadow derailleurs is that tracking across the cassette is almost totally down to patallelogram angle, plus B-tension adjustment. With the older sprung top pivot design the derailleur will successfully track a larger range of cassette sizes as the whole mech can pivot up or down on the dropout as needed.

      The FD cage on the R80x0 is much more compact than the 68×0 – the attachment between the two sides at the rear is inside the cage rather than below it. This gives more chainstay clearance so smaller outer rings will work than with 68×0. The new (mechanical) design gives more tyre clearance too, and removes the need for a barrel adjuster.

    • JOM JOM

      One thing I learned about the Shadow design derailleurs. They are very sensitive to B-screw adjustments. If you turn the B-screw in a decent amount to cater to a bigger cassette, shifting will be horrible on a cassette such as a 12-25. But, back off the screw and shifting perfection returns.

      I played with the latest DA Di2 hydro levers recently… their brake travel was much less than the R785 levers. I hope that trickles down to whatever Ultegra Di2 hydro levers we see?

      • Avatar stephen

        Re Dura-Ace versus Ultegra hydro levers: I went to the local Shimano 2018 product launch here in Sydney and the shapes of the DA and Ultegra levers appeared to be identical. However, the Ultegra samples they had were non-working 3D printed parts. The Dura-Ace hydro levers (both Di2 & mechanical) are available, but the Ultegra 8020 mech/hydro levers had an ETA in January 2018 last time I looked. Given how far the 9120 lever delivery dates were delayed I wouldn’t be surprised if this was optimistic.

        • JOM JOM

          Stephen, thanks for chiming in about this. Ironically, Shimano ran a “flash” sale on their S-Tec USA website for 8050 Di2 derailleurs, Ultegra flat-mount disc brakes, and rim brake Ultegra Di2 shifter levers. No hydro stuff.

    • Avatar Sidhenidon

      KCNC makes 11-38t titanium cassettes. 😀

  6. Avatar Tom

    Sorry to duplicate some of what’s already posted above, but I really need to know whether the RD-R8000 (Ultegra Shadow mechanical mid-cage) will accommodate an XT CS-M8000 11-40t (11-speed MTB cassette) when paired with 46/34t chain set. This setup requires a 41-tooth capacity, but the listed capacity on the RD-R8000 is 39t. With only a 2-tooth difference, I’m guessing it will probably work with the B screw slammed, but who knows for sure.

    My other option is to take the long cage off a Deore RD and put it on a 105 RD, which would give me a capacity of 45t. The cost is about the same either way, but I’d rather go with the RD-R8000 if it’ll really work.

    JOM you say it’s almost certain to work. Do you have reservations, caveats or more details? Thanks!

    • JOM JOM

      Caveat is… don’t run the big chainring / big cog combo, especially in the field.

      I am pretty confident, based on what I demonstrated with the DA Di2 derailleur, that a 40T won’t be a problem with the longer cage Ultegra version. Remember, I haven’t tested this setup, so please don’t hold me accountable if it doesn’t work! Experimentation is how much of this works.

      • Avatar Tom

        Solid advice. I can be a sloppy shifter, so I’ll take that warning seriously. Thanks, man.

    • Avatar stephen

      If you look at Lennard Zinn’s tech column at velonews:


      …someone fitted a T670 SGS cage to a 5800 rear derailleur and used it successfully with 50×34 & 11-40. The 5800 uses a different cage attachment to 6800/9000 so this mod won’t work with those – the exploded diagrams at si.shimano.com are a useful resource. That cage or one of the other “trekking” series SGS cages *may* fit the R9100/R8000SS/R8000GS RDs based on the exploded diagrams as they look similar, but without actually trying things I’m only guessing. 🙁

      Re R8000GS: This is claimed to have 39T capacity as opposed to 37T for 5800GS. The R8000 cage appears to be longer and Specialized certainly think the *5800GS* will handle 41T as that’s what it does on the Sequoia Elite with 48×32 & 11-36; I can vouch for it working. If you look at the exploded diagrams for the R8000SS/GS, it appears the only different parts are the cage plates and what Shimano are calling the “End Adjusting Bolt” (part #5), which is 3mm longer on the GS; this is analogous to the B-tension screw on trad derailleurs.

      Until someone actually tries the R8000GS with an 11-40 it’s impossible to be certain, but chances of success are good IMHO. I’ll probably buy one and try it at some point, but please don’t hold your breath waiting. 🙂

      I note also that the R8000SS/GS and R9100 RDs have the top jockey wheel concentric with the cage pivot, so the only things which are going to affect shifting are the “End Adjusting Bolt” and chain length. This assumes the R8000GS uses the same patallelogram angle as the SS version, hard to tell as the exploded diagrams don’t give a part number for that. My guess is that they are probably the same, but without having them side by side there’s no way to be sure. If parallelogram angle *is* the same, the GS RD should be fine with smaller cassettes too, just a few grams heavier than the SS version.

      • Avatar Tom

        I don’t think I had seen Zinn’s article. Thanks for posting that. He’s absolutely correct in saying the cages from some Shimano MTB RDs will not fit some road RDs.

        I am virtually certain the Super Long Cage (SGS) from the Deore LX 10-speed (RD-T670) will fit onto the 105 RD because they have the same mounting pin, according to the respective Shimano exploded views. That Frankenstein combo should produce a 45t capacity, which is enough to combine a 50/34t crank with an 11-40t cassette.

        In this video, the guy gets the 11-40 to work – barely – with the RD-R8000. He never says what size the chain rings are, but they look like 50/34. I don’t consider this conclusive video evidence. Therefore, JOM’s ruling on the field stands – proceed with caution.

        • JOM JOM

          The bloke making that video really needs to orient the camera a bit differently.

          One of my friends has a 40T cassette laying around… I will have to see if I can get the 9150 DA Di2 derailleur to shift to it… could be very suspect!

    • Avatar Tom

      Well, Santa brought me an RD-R8000, an XT 40t-11t cassette and a new chain. After a 3-hour gravel ride yesterday with lots of steep hills, I can confirm the new Ultegra derailleur and the 40t MTB cassette work flawlessly together when paired with a 46/34t crank. I put the chain in all the worst situations, like shifting from big/big to little/big and then downshifted while going uphill, and it never missed a beat.

      The first adjustment I made in mounting the RD was to slam the B screw all the way down. That move provides good clearance between the top jockey wheel and the 40t sprocket. Initially I had some shifting problems, but I put in a new cable and shortened the housing, which fixed the problems. My Lynskey Cooper CX has full cable housing. This new RD does not move vertically like my old 6800, and you need very little slack in the housing where it approaches the mech. Once I shortened the housing and remounted it with the new cable, everything worked perfectly.

      Yes, the 40t is overkill for most routes, but it will be great for Southern Cross and any other mountain ride, as well as MTB trails. This combo performs so well, I may just leave it on my bike all the time. The RD-R8000 is a significant improvement over the 6800, which is a really good RD. The new one keeps better tension on the chain, especially on rough gravel, which results in better shifting. So, go knock yourselves out!

      • Avatar stephen

        ^ Were these the GS (long cage) versions of the 6800 & R8000?

        I recently got an R8000GS too and have been wondering how small a cassette will work, so will try it and report back; I’ve got 11-23 & 12-25 as well as a couple that are officially meant to work, and 11-42/46. I’m really hoping both 12-25 & 11-40 will shift okay, but we’ll see.

  7. Avatar Ronnie Bryant

    Just got my 8050 GS rear derailleur. I was able to get the 11×42 XT Cassette to work just fine with a 46×34 crankset – Pu the “B” screw almost all the way in. I also used an 11×40 and was able to shift into the Big Big combo – I will be running full Syncro Shift so I will never be in that combo. This makes big hills much better and can also be used for loaded touring.

    • JOM JOM

      Excellent! Thanks for chiming in. We tried a 40T cog without issue, glad to gear the 42 works well, especially with a 46 x 34 combination! You should be able to climb telephone poles with that uber low gearing 🙂

      • Avatar stephen

        ^ Well, maybe if they’re laid flat on the ground!; FWIW, I ran 32×42 (shifted poorly with 5800GS & Roadlink) in the Blue Mountains and could have used another gear or two. It’s good to know 11-42 might work, though I think 42×27 plus 11-40 should hopefully be enough for touring; I’ll find out after my frame arrives, hopefully in April.

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