Electronic & Hydraulic Shifting (Di2, Ui2, customisations)

Can confirm what @hippy says, I've also got an R8050 rear mech working with a 6870 front mech and actually I think 6770 shifters with no firmware updates

My setup uses the old R785 (pre-Ultegra) shifters too. It also does the anti cross-chaining thing, which surprised me.

Mine does, but only for small-small. Unless that's how it's meant to work?
I was running 52-34 with a 30 cassette, which apparently shouldn't work. It does, but the new derailleur locks out the small-small to stop the chain drooping

Oh wait, just re-read what you said. Yeah mine doesn't do the anti-cross chain...

You can mix 11 speed road/RX/GRX mechs from any generation pretty interchangeably, but not the 6770 10 speed stuff. Also pretty much all of the shifters ever made (bar the very obsolete 7970 Dura Ace) for any family (road/mtb/e-bike) can be used on any setup, even with the newest kit.

All of the smarts are in (I think) the battery firmware, so you get the anti slack chain feature with whatever shifters if it recognises you have one of the rear mechs that wants it.

Yeah 11speed and 11speed 👍🏻
I know it’s a front mech but apparently an 11speed rear and 10speed front don’t work together

@TooTallTim 6770 shifters don’t care if they’re 10 or 11 speed...
@grams yes, this

There's three modes, Full, Semi and Off or something like that.
"Full" stops both ends of crossing chaining by automatically shifting the FD as required, "Semi" stops small-small and "Off" does nothing. You can change it on the Junc A with press duration. Google it.
I have my race bikes either Off or Semi because big-big cross chaining is sometimes preferable to dumping chain into little ring.

Shimano's teeth limits are always very conservative because -some- frame combos might not work. It's typically a case of try it out and see. I use 34/46 with an 11-42T cassette just fine on R8000 kit.

Ah, I never had any 10spd electronic. I work in software - you NEVER buy the first version :)

8050/70 locks you out of small small regardless of what mode you're in. 6870 you can still get into small small in manual mode.

Where is that controlled? I quite like it. Not that I'm in the habit of cross chaining but sometimes on ultras I go up gears forgetting I changed into the little ring a while back. It's nice feature but I guess you need to two deraillers talking to each other for it to work.

This is saying it's controlled based on chainring and cassette sizes, but how does it know what sizes I'm running? That sounds like bullshit to me.

https://forums.roadbikereview.com/components-wrenching/shimano-ultegra-di2-r8050-cant-shift-into-smallest-2-cogs-when-small-chainring-364072.html

I mean, this is for people trying to override the settings in the app. By default it must be in Semi-auto mode, because I've never adjusted anything with an app, just the Junc A.

I'm on the old battery, pre BT, so I shouldn't have that function. I've literally no idea why it does it now, haha

Ah, that'd be why then

Putting the charging junction inside the seatpost/seattube, with enough cable to pull it out every so often to charge... Any reasons it's a stupid idea? Go.

I don't know what batteries are in mine. I've never waved BT near them.

Because who wants to remove the seatpost every time you charge? You also lose the ability to fine tune gears on the fly, take bike out of crash mode, etc.

I probably only charge 3-4 times a year, Ive changed seatposts more often than that. And in the 5 years I've used Di2, I've never had to tune gears once initially set up, or use the crash mode

Sods law I'll need to once I try this

If you plug your junction box into a PC you can adjust the cassette and chainring sizes that are stored in the battery's memory chip. I think by default it's set to 52/36, 11/28.

Or if you have the newer battery and BT wireless unit you can do it on your phone.

Only useful if you use synchro shift (full or semi). Also helpful if you like having your gear ratio shown on your Garmin/Wahoo.

Currently, I've got wires coming from each shifter to the junction attached to Raceware mount, zipties trying to keep it all tidy. Then wire into frame.

The plan is to run one wire across the shifters through internal handlebar routing. Then one really long wire shrink-wrapped to the rear brake housing into frame, then stick everything in the seattube where it's not exactly hard to access every month or two.

Cleaner looking and cheap solution.

It does depend how much you use your bike. I have to charge mid-race during ultras so hiding the charge port is pretty silly. I also like to leave my bike in places where it will definitely fall over onto the derailler and I have been know to throw myself off hairpins in the middle of the night for some lols.

You ride further in one race than I do in a month sometimes...

Cleaner looking and cheap solution.

You could lose the Junc A altogether and hack together an e-tube charger. It's documented somewhere.

https://forum.slowtwitch.com/forum/Slowtwitch_Forums_C1/Triathlon_Forum_F1/How_to_charge_a_completely_internal_DI2_Setup_P5546327/

Yeah, there's no amount of "clean looks" that will make me hide my Di2 junction box :)

Maybe on the TT bike for aeroz but that'll only do 24hrs in one go.

Oh well, shit. Accidentally bought 6870 setup on a whim. About 500 euros excluding brakes, crankset and charger.