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Welcome to the Future.
Shimano's refinements to the latest Ultegra Di2 group is truly remarkable and while we always fancy a full Dura Ace build, we'd be hard pressed if we could 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 Shadow low profile 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 are 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
- Item #SHI00G5
- Q & A
I almost bought DA
- Familiarity: 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. email@example.com
Is this derailleur compatible with the 6870 Di2 group? (Replace RD6870 with RD8050)
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!
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.