hobkirk

In my ongoing saga: I bought some 6770 shifters, now I'm finding I can't find a 6700 RD. 10-speed is fine, but can I use a 6800 RD w/ my 10-speed cassette?

• I believe I can upgrade the 6770 shifter firmware to 11-speed
• Then I could use a 6800 RD, although it'd expect 11 gears
  2. Are the RD throws on 6700 and 6800 the same? (there's just one more, which I believe the 6770 shifter firmware can be modified to allow)
  4. Are the FD throws on 6700 and 6800 the same?
  6. Are the FD throws on 6700 the same for doubles and triples?
  8. Could I use a 6800 RD with a 10-speed cassette, using the limit screws to prevent "overshifting" past the 10th gear?

This process, upgrading to a 10-speed Di2, is more involved than I expected. Too much enthusiasm, too little knowledge. Unsurprisingly, it's not the first time I've done stuff like this.

Thanks for your tolerance, as always.

trailflow1

No. if you plug in the 6870 RD (and update the firmware - which i needed otherwise it wont work at all). The system will run as 11 speed. The RD determines what speed the system is.

Correct. but once you do. It is not reversible.


1. No. 11 speed has different spacing. The gaps between the cogs are slightly smaller.

2. If you update the firmware to 11spd. You need to buy the 6870 FD. The old 10spd 6770 FD will not work. You cannot mix and match 6770 and 6870. If you don't do the update the 10spd 6770 FD will only work with the 10spd 6770 RD.

3. There is no triple option for any Di2 system. Only double. There is no way to re-program it for a triple.

4. No. The spacing is different. Removing 1 cog from the 11 speed cassette is not advised with Di2 because the makeshift limit stop could potentially damage the motor and it may also cause the battery to drain. That's what happens on the low limit if it is too tight against the stop. There is a safety feature built in that automatically shifts down to the next cog if it is set too tight so i imagine it would be the same at the other end of the cassette.

Your options are -

Find a 6770 FD and RD on the forums,ebay,classifieds,NOS etc.

or fully commit to 11 speed. Meaning you need to buy both 6870 FD and RD's. 11spd chain and cassette. And an 11spd compatible rear wheel/hub. And a double chainset by the looks of it.

When you combine and add up the seperate prices for the shifters,derailleurs,junction boxes(x2),wires (x6),battery,charger,chain,cassette and wheel.

It may work out cheaper to just buy an 'upgrade kit' available from some british retailers like Merlin cycles or Ribble.
And source the rest yourself.

Shimano Ultegra 6870 Di2 Gear Kit | Road Bike Electronic Components | Merlin Cycles

Shimano Di2 Ultegra 6870 11 Spd Double Gearset at Ribble Cycles

Beware that you have an Internal or External battery option to choose from. That's if your current frame is internal Di2 compatible.


A common misconception of Di2 is that it auto adjusts on installation. This is not the case. Setting it up is the same as a mechanical set up. If you hold the button on the junction 'A' box. It goes into adjustment mode and you can make fine micro adjustments of the derailleur position in the middle of the cassette to eliminate any chain chatter on the next cogs. This is done via the buttons on the levers. Once set the derailleur should run perfect and silently across the full range of the cassette.

(for any confusion - the '6800' RD refers to the mechanical version. '6870' is the Di2 RD)

hobkirk

Outstanding reply. I know significantly more than I did before. Thank you!