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ShimanoUltegra Di2 RD-R8050 Rear Derailleur

$279.99 - $286.99

Item # SHI00G5

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  • Gray, Medium ($286.99)
  • Gray, Short ($279.99)
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Item # SHI00G5

Why We Like The Ultegra Di2 RD-R8050 Rear Derailleur

Shimano's refinements to the latest Ultegra Di2 group are truly remarkable, and while we always fancy a full Dura-Ace build, we'd be hard pressed to decipher a difference in performance. That makes sense since Ultegra gets Dura Ace trickle down technology, and for rear derailleurs, the RD-R8050 borrows heavily from the firm's top-end Dura-Ace RD-R9150—including the low profile Shadow design. This profile places it closer inbound to the frame and tucks the derailleur under the cassette. This protects the derailleur in the event of a crash and in general from getting banged around, so it remains better aligned making shifts smooth, quick, and accurate. The RD-8050's new geometry allows for shorter throws that result in faster and more precise shifts even over a wider range 11-34 cassette.

We're smitten with the performance of Shimano Di2. Derailleurs using spring and cable tension to move the chain from cog to cog almost seems archaic compared to electronic rear derailleurs, where the highly innovative digital technology of sending electronic signals to a motor to precisely position the chain exactly where it is needed on the cassette. Shifts happen much quicker and with less effort. Shimano even employs a saving mechanism that disengages the rear derailleur so it can handle side impacts without damaging the component. Shimano's excellent E-Tube software allows total customization including shifting speed, the number of cogs shifted with a press and hold of the button, and even what button does what.

A note on the cage length: Shimano offers the 8050 derailleur in two cage versions, an SS version that works up to a 30T cog and a medium cage GS version that works up to a 34T cog. The GS version can be used with Dura Ace Di2 if you want to use a 32T or 34T cassette with a Dura Ace group as that group only offers one short cage rear derailleur option.

  • Rear derailleur for electronic shifting
  • Slimmer Shadow plus profile
  • 11-speed shifting for wide gearing options
  • Mid-cage accommodates up to a 34t cog in the rear
  • E-tube technology for customizing shifts
  • Built-in crash safety protection

Tech Specs
Capacity[short] 33T, [medium] 37T
Cassette Range[short] 11-30T, [medium] 11-34T
CompatibilityE-Tube Di2
Manufacturer Warranty2 years
Activityroad cycling

Actual Weight

Gray, Medium
Gray, Short

Claimed Weight

Claimed weights are provided by the vendor.

Have questions? Chat with a Gearhead

[short] 8.5oz (240g), [medium] 8.7oz
240g), [medium] 8.7oz (247g

Actual weights are measured in-house by the Competitive Cyclist team.

Have questions? Chat with a Gearhead

What do you think about this product?



I am looking for the Shimano Ultegra Di2 RD-R8050 Rear Deraileur GS Cage. Could you confirm that the long cage version is in fact the RD-R8050-GS? the picture shown for long cage version doesn’t match the one shown on Shimano’s website. See Thanks so much for you help!


what's the different between SHIMANO Ultegra RD-RX805 vs. RD-R8050 Rear Derailleur? is it just a clutch?

>Rating: 5

Welcome to the future

DI2 is incredible. I have ridden every kind of component in mechanical form and now switching to electronic shifting I am blown away. The shifting is crisp, clean, and reliable. My favorite part is once set up, maintenance is next to none.

If you live in a hot/humid area, the derailleur will require lots of maintenance...the pivot bolts need to be lubed very regularly, otherwise the derailleur will seize up and not shift

I agree been Using Di2 for 4 and half Years first Problem front Derailleur Motor Quite Throwing to Big Ring Replaced Good as New Again Easy to Install.


will this model fit my ten speed Di2 Choose a photo No

Sadly, no. This is an 11 speed rear derailleur.


will this model fit my di2 ten speed I have a short cage

>Rating: 5

Robot Bike Love

I've put it through the wringer

There are so many things I can say about Di2 but I will keep it simple, it just works flawlessly. I can go most of the season on a single charge and every shift is perfect, even when my technique is sloppy. The long cage version of this derailleur will go up to an 11-34 cassette which is great especially if you are just starting out in hilly terrain or if you are a veteran that likes to spin a smooth 90+ cadence on steeper grades.


My derailleur cage is bent on my di2 9070 rear derailleur after an accident. Really don't relish the idea of dishing out $540 for the current DA rear derailleur. Would this one work with my setup. I have a 11-28 cassette. An update to my prior question: Forrest, I forgot to mention I have an all Dura-ace di2 9070 setup. Maybe you got that when I mentioned 9070, but I've heard or read that some Di2 stuff between dura-ace and Ultegra don't like each other. Is this true or not? Or should I be okay as you mentioned before?

Yeah it would plug in and work fantastically.

The Ultegra RD-8050 will work with the Dura Ace DI2 11 speed shifters.

>Rating: 3

Can not remove my rear wheel!

I've used it once or twice and have initial impressions

I purchased the long cage version and and a 11-34 cassette. I put it on my bike today. I am going on a trip to the mountains soon and have a Cannondale super six with disc brakes. I got the derailleur on with only minor issues but I can not remove my rear wheel without taking off the derailleur. I hope I don't get a flat tire. Be careful. This doesn't play nice with all bikes.

I have the same problem (cannot remove rear wheel with mid-cage version of the derailleur). A better solution than removing the derailleur is to deflate the rear wheel. Still less than optimal and this would be a real problem for people who race (that is not me though). I am checking with my LBS later today to see if there is a better solution.

Just got back from LBS. When you pull the derailleur back it feels like it stops at a certain point that is not back far enough to remove the wheel. It turns out that the rear mech will pivot further around a different bolt until you feel a second stopping point. Just keep rotating. That second stop is easily far enough to remove or mount the inflated rear wheel. Once the mechanic showed me how to do it it is as easy as on a short cage. But it is not intuitive. One other thing I learned is that Etube sets a default as 11-32 for the rear cassette if it detects that it is mid-cage. I suppose Shimano figures that most people buy the mid-cage so they can run big cogs for hills. But if you are actually running an 11-28 it is impossible to properly index gears unless you go into Etube and change that setting. Once you make the change it is easy to get things flawless.

>Rating: 4

I almost bought DA

I've used it several times

I just built up a 2015 Sworks Tarmac Disc and was trying to decide. Do I go Dura Ace or Ultegra? Previously there may have been a big difference, besides price. This version though is so close to Dura Ace that the big difference I saw was price. I went Ultegra and it is great. Mount and setup are easy and the weight and function are very similar. I am happy with my choice. There is still a place for Dura Ace because it is the uber groupset, but Ultegra will work fine for me. And it is cheaper to replace when i lay it over in a crit race. Let me know if you have compatibility or function questions.


Is this derailleur compatible with the 6870 Di2 group? (Replace RD6870 with RD8050)

Hey Alan! This rear derailleur is absolutely compatible with the 6870 group. Let me know if you have any questions and I'd be happy to get one on order for you if you'd like! -Kody

My local bike repair man called Shimano and said that all you need to buy is the RD8050 rear derailer and the 11-34 cassette and that it will work on the other 6870 di2 parts.

Everything on my bike is 6070 except the 8050 rear derailleur. Works perfectly. Just make sure Etube knows what rings and cassette you are running.