Bought a new Di2 rear derailleur and need some help installing it? Read how to install the RD-R8050 / RD-R9150 / RD-6870 / RD-9070 Di2 rear derailleurs.
Medium Cage Rear Derailleur
The Shimano RD-6870-GS is the medium cage rear derailleur for the 6870 series.
It supports a max front difference of 16T, a low sprocket minimum of 28T and a low sprocket maximum of 32T. The top sprocket maximum is 12T and the minimum is 11T. It has a total capacity of 37T and weighs only 11g more than the short cage derailleur - 268g.
It also features Shimano's Crash Protection Mode - this prevents shifting after a crash to make sure the rear derailleur is damaged any further. To restore shifting functionality have a look at the FAQ: I had a small crash and my rear derailleur stopped working.
When paired with the BT-DN110 battery, synchronized shift is enabled for this derailleur. Read more on synchronized shift in the complete guide to synchro shifting.
- Model code: RD-6870-GS
- Series: Ultegra (6870)
- Weight: 268g
- Speeds: 11
- SD50 ports: 1
- Max front difference: 16T
- Total capacity: 37T
- Low sprocket max: 32T
- Low sprocket min: 28T
- Top sprocket min: 11T
- Top sprocket max: 12T
- RD type: Non-shadow RD
- Clutch: No
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Indexing, trimming, or fine-tuning Di2 rear derailleurs is done through micro-adjustment. Read how to set up your Di2 rear derailleur perfectly and ride without those grinding noises.