Delving into di2 - Help me!!

Hello all.

I have purchased a new Genesis Datum gravel bike. This is capable of being internally routed, but not my handle bars.

I have decided to treat myself to a di2 upgrade. However, it seems to be a mine field of junction boxes, batteries, cables, charging points etc.

I am looking at the Shimano GRX 815 1x system (if I can find stock).

Can anyone advise on what other bits to purchase. My handle bars aren’t capable of being internally routed so I would assume I would need the junction box that would be situated under the stem as opposed to the bar end plug type?

Thanks in advance all.


  • PMark
    PMark Posts: 159
    edited January 2022
    You might want to have a look at SRAM axis instead, it is wireless so you don't have to worry about junction boxes/cables etc, plus it is better if you are going for a 1x system (wider gear range).

    The downside of Axis at the moment is 12 speed spares (chain/cassette) are generally more expensive and you would need to change the cranks and rear wheel freehub (to support 12 speed).

    But if you really want 11 speed Di2, then Merlin do group sets with all the parts you need.

    Edit: Just be aware there are both disc and rim brake versions of the electronics group sets and the rim brake ones are often a lot cheaper (not always obvious which is which without checking model numbers).
  • BetterShifting_Terry
    edited January 2022
    If you want Di2, you'd need:

    - Junction A (the SM-EW90-A under-the-stem you mentioned would work, yes. Alternatively, SC-MT800 display. Comes with BluetoothLE/ANT)
    - Battery charger: SM-BCR2
    - Junction B (SM-JC41). Technically you can do without. But don't :)
    - Rear derailleur: either the GRX 1x RD-RX817 (max 42T), or the MTB RD-M9050/RD-M8050 (max 46T).
    - Shift levers: ST-RX815 (GRX hydraulic disc) would be a good choice :)
    - EW-SD50 wires
    - Battery: BT-DN110
    - Seatpost battery holder (assuming you're putting the battery in the seatpost)

    (I'm assuming you're building a disc brake bike here)

    SRAM (full) wireless would work too, of course.

    If your current bike has Shimano brakes installed on them, keep in mind that you would also need to replace those (and the hoses) if you switch to SRAM.
    Same the other way around - if you're on SRAM brakes now, they won't play nice with Shimano shift levers.
    I run - Di2 help / tips / guides
  • t_willo
    t_willo Posts: 16
    Amazing. Thank you
  • MattFalle
    MattFalle Posts: 11,644
    how much would that little lot cost out of interest?
    The camera down the willy isn't anything like as bad as it sounds.