Electronic & Hydraulic Shifting (Di2, Ui2, customisations)

No
Yes

oh and to connect two tt levers to a di2 system presume i need two cables to connect to the 3 port junction box , then one down to a junction box and then another cable to the rear and only deraullier, i have another di2 bike so if a front der is needed for setup thats not a problem.

You dont need a front mech at all for 1x.

Also the TT shifters have cables attached to them already so you don't need to buy those.

You can carry the cylindrical "internal" battery in a case next to the bottle cage. This gives you charging via the front junction and the case also has 6 ports, replacing he lower junction. Oh, and internal wiring.

my thinking was that the internal battery is 130 vs 45 for the external one, plus i have a spare mount for an external battery

Oh Merlin have new DI2 in stock and its £2800

Watch out, I thought these climbing switching connected to the STI shifters and not the junction box?

From what i've read, it's the sprinters switches you can't connect directly to the junction box.

The climbers ones have all the tech inside them to operate by themselves.

The R610 sprinter switches connect to the brifters because they don't have their own chips to join the CAN bus with. R600 Climbing/Pave shifters connect to the junction box because they have their own chips.

Oh I see, my bad for the confusion then. What follows is that to use climbing shifters and sti a 5-ports junction is needed?

You can still plug the climbing shifters in to the sti

If you can, they're not r600 climbing shifters.

Can I get 10 speed 7971 TT shifters working with 11 speed?

No.

Different wires, different system..

7900 Di2 is the old pre-eTube version. Not compatible with anything.

Bummer. Thanks @Jaap and @Emyr

They're a LOT cheaper. Now I know why!

Uhm, planning on using some Di2 Climbers switch so I can use Di2 on some loop bars which means I will need to get some flat bar brake levers. Is this a stupid idea? If not, do I need to get two to control the front and rear derailleurs? Are there any other options available? I have 6870 for reference.

You could also use the di2 XT shifters (http://www.chainreactioncycles.com/nl/en/shimano-xt-di2-m8050-11-speed-shifter/rp-prod148576) instead of climbers switches.

Now onto the complicated bit, you prefer to use 2 buttons with 2 derailleurs, correct?

Shimano has something called "synchronised shifting" where you can setup the moment it switched chainrings through the PC software, but this needs a certain combination of junction box, battery or derailleurs. You can find out about it in their compatibility chart (http://e-tubeproject.shimano.com/pdf/en/HM-CC.3.2.0-01-EN.pdf). They are ordered by battery, then derailleur (scroll through it). It's not an easy thing finding the right parts for setting up synchronised shifting, so you could just go for the easy solution and mount 2 shifters.

Hope it helps :)

y no 1x?

synchronised shifting

SC-M9050, SC-M9051 or SC-MT800 is required for synchronized shift, plus MTB mechs, but roadie shifters are ok, including R600 pave shifter.

Was actually thinking of 1x, just dont know where to start yet. Will be going down that route after though, definitely

XT Di2 rear mech, the new battery and the display!
MT-800 series.

will need to check that out, if I need to sell my 6870, then selling it will be
Thanks!

No it's not that simple, you can use 6870 parts. You just need the right junction box and battery

from http://carltonbale.com/shimano-di2-everything-you-need-to-know/ :

Synchronized Shifting and Bluetooth Wireless Units can be added to all
E-tube Ultegra and Dura-Ace systems but the battery has to be upgraded
to the BT-DN110 Internal Battery or BM-DN100 External Battery Mount.
To add Bluetooth capability, a EW-WU101 or EW-WU111 inline transmitter
must be added to road bikes and for mountain bikes, the SC-MT800 or
SC-M9051 display/transmitter unit must be added.

So @Shroom you can just about do anything, but it all depends on what parts you have and how fancy you want everything..

i have the full 6870 groupset. So, what exactly do i need to run loop/flat bars? the first one you linked looks good, XT shifters