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Shimano Ultegra Di2 RD-6870 Rear Derailleur

Sale $159.95 - $169.98 $228.99 28% off

Item # SHI0657

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  • Gray, Short Cage ($159.95)
  • Gray, Mid Cage ($169.98)
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Item # SHI0657

A close second.

Shimano’s Ultegra Di2 RD-6870 Rear Derailleur features much of the same level of performance as the Dura-Ace group without the podium-topping price tag. Taking its cue from the Dura-Ace 9070, the profile of the 6870 has been trimmed, making it leaner than the previous Ultegra Di2 rear mech. The 6870 Di2 rear now also has 11-speed shifting capability with sleeker, more professional-looking wiring and a mid-cage version that can accommodate a 32t cog in the rear.

Shimano’s electronic shifting features E-Tube technology, which allows you to customize shifting speed and even program how many gears the rear derailleur shifts through when holding the shift button down. Finally, the 6870 rear derailleur has built-in crash protection. In the event of an accident, the rear mechanism will actually compress and tuck away.

  • Slimmer profile
  • 11-speed shifting capability
  • Mid-cage accommodates a 32t cog in the rear
  • E-tube technology
  • Built-in crash protection

Tech Specs

Material:
aluminum
Actual Weight:
Gray, Short Cage: 270g
Recommended Use:
road cycling, cyclocross
Manufacturer Warranty:
3 years

Size chart

Shimano

Di2 Reference Guide

 

Note: This reference is meant to be used as a guide for creating a Shimano Di2 drivetrain package. For further assistance please feel free to give us a call.

 

Battery and Wires:

Our Shimano Di2 packages are built for three standard configurations based on battery location and wire routing. First, you'll need to determine if your frame uses an internal or external battery mount, and whether the routing is either internal or external. Below is a guide for which battery, charger, mount, and junction boxes are required for your configuration.

Battery and Wire Configurations
 BatteryBattery ChargerBattery MountJunction AJunction B

External Battery

w/ External Routing

SM-BTR1 SM-BCR1 SM-BMR2 SM-EW90 A/B 3/5 port SM-JC40

External Battery

w/ Internal Routing

SM-BTR1 SM-BCR1 SM-BMR2 SM-EW90 A/B 3/5 port SM-JC41

Internal Battery

w/ Internal Routing

SM-BTR2 SM-BCR2   SM-EW90 A/B 3/5 port SM-JC41

Battery Mounts:

The SM-BMR2 battery mount is available in three configurations -- Long External, Short External, and Long Internal. Both Long versions are to be mounted using the bottle cage mounts, while the Short version is designed for Di2-specific frames with either a chainstay or down tube mounting location.

 

Junctions:

There are two junctions needed for completing your Di2 build -- A and B.  Junction A, SM-EW90, is located at the handlebars and available in both three- and five-port options. The three-port option is intended for standard shifting with a left and right hand shifter. If you have the intention of using Shimano's satellite sprint shifters, or a combination of time trial shifters and shifter/brake levers, the five-port junction box will be the necessary selection.

Depending on your frame specification, Junction B (SM-JC40 or SM-JC41) is located either internally or externally at the bottom bracket area. Accordingly, SM-JC41 is designed for frames with internal wire routing, while SM-JC40 is intended for external wiring options.

 

E-Tube Wires:

For your convenience, we've created wire packages for your Di2 build kit in the sizes Small, Medium, and Large. Below, you'll find which wire lengths are included in each kit. Additionally, we've recommended a kit size based on your frame size.

 E-Tube Wire Length Chart
 SML
Down Tube Wire 700mm 750mm 950mm
Front Derailleur Wire 300mm 350mm 400mm
Rear Derailleur Wire 500mm 550mm 600mm
Battery Wire 300mm 350mm 400mm

 

 E-Tube Wire Frame Size Guide
 SML
Frame Size  47-52cm 53-56cm   57+cm

Please Note:

E-Tube Wire length suggestions are an approximation. 

Reviews & Community

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Nice!!

  • Familiarity: I've put it through the wringer

I've had the 6770 and now this 6870 and the work just like they should, quite, fast and precise. The 6870 is much smaller than the previous 10 speed 6770, the cable hides better too since the exit port come in the back between it and the seat tube. Don't spend extra for Dura-Ace, unless you get it at the same price, Ultegra is just like dura Dura-Ace, just a few grams heavier, diet for a week and your there.

Avg. ride time: 3h 24m per week
  • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

Durable & Precise

  • Familiarity: I've put it through the wringer

I've been extremely impressed with the performance of the Ultegra Di2 rear derailleur. I've logged considerable miles off road on my gravel bike, and while it's been banged around a bit, it hasn't missed a beat. It still delivers precise, quick shifts every time.

Durable & Precise

Reliable

  • Familiarity: I've put it through the wringer

I purchased a bike with Ultegra Di2 about a year ago. It was my first foray into electronic shifting and it's just flat out reliable. The batteries last forever and you get quality dependable shifting. In the year that I've had it, I have had zero hickups.

I am currently running Ultegra 6770 Di2 10 speed drivetrain. Can I convert to the newer 11 speed by changing to a Ultegra 6870 rear and Front derailleur, cassette, and chain or will I need the new junction box too?

One bike mechanic told me that you need to replace the brake shifters as well because the 10-speed shifter only accommodates 10-speeds. Plus, there's the question of whether your old Di2 has an external battery that you'd like to replace and make it internal. In that instance you'd need wiring, the internal battery and a junction box too. One other potential issue is whether your rims can accommodate 11 speeds. I discovered that not all 10-speed rims can accommodate 11-speeds.

Avg. ride time: 9m per week
  • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

Solid, fast shifting

  • Familiarity: I've put it through the wringer

I've been riding this RD since last Oct. 2015 and it is awesome. Super quick, precise shifting RD that was very easy to install and set up.

Sticking with it!

  • Familiarity: I've put it through the wringer

Building a new bike is always exciting and it's always tempting to try new things. The drivetrain decision was particularly easy this time however, after my previous experience with Ultegra Di2. The light weight and sexy lines of the Dura Ace Di2 group are indeed tempting, but for the cost you can't go wrong with the Ultegra. I have had exactly :::zero::: issues with my previous group other than problems I have inflicted (read: derailleurs are not-crash-proof). This also makes the Ultegra a great option if you race, where close quarters and periodic pavement sampling are a fact of life.

Works great, easy to install

  • Familiarity: I've put it through the wringer

I bought this as part of an upgrade to 11-speed for my Trek Domane. Installing the derailleur was the easiest part of the installation. I got the medium cage because I wanted to use a 32-tooth cog on my cassette.

The derailleur was very easy to install. I don't have the special tool Shimano recommends for disconnecting and connecting the Di2 wire to the derailleur, but I did it easily with my fingers. I disconnected and unbolted the old derailleur and bolted on the new one. I connected the wire, and tested it - it worked immediately.

After putting on a new 11-speed chain, I ran through all the gears and it worked right away. Adjusting the Di2 is simple, first the limit screws and then the shifters. All 11 gears worked immediately, and the derailleur is fast and quiet. I've used it a lot on steep hills and on the flats, and it works like Di2 should - accurate, fast, and quiet.

Avg. ride time: 8h 17m per week
  • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

best der ever

  • Familiarity: I've put it through the wringer

I have no review that would actually convey my feelings for the DI2. I love this stuff, mechanical is dead, long live mechanical.

Flawless shifting, great value!

  • Familiarity: I've put it through the wringer

I have been riding a full Ultegra Di2 setup for more than a year and I am never going back to mechanical if I can help it! Why? Perfect shifts, front and rear, easy setup, expandability (currently using the

Flawless shifting, great value!

I am currently running Ultegra Di2 10 speed drivetrain. Can I convert to newer 11 speed by changing rear derailleur, cassette, and chain or will I also need to change shifters?

Best Answer

Bill,



Ideally, you want the entire drivetrain to be Di2 but you can make do with rear derailleur, cassette, and chain. The front shifting won't be perfect, but it will work. Shifters, Wires, and battery don't need to be updated but you may need to plug them in for a firmware update.

consistent & reliable shifting

    i'm running the 6770 on both of my road bikes and i love how effortless the shifting is. no missed shifts, no adjustments for cable stretch/fatigue that often results in chain rattle. i have > 2,500 miles on these derailleurs and they have been very reliable, even in long rainy rides. battery life is sufficient for several months of shifting between charges. micro adjustment makes dialing in various/different cassettes very easy to do, even on the fly. i will never go back to mechanical.