R8100 front mech not working

focuz

Not long received my Scott Foil with R8100, fiddling around with the seatpost and taking it off and on only to find the front mech not working now.

I can see in the seatpost battery there’s only one wire going into it. Assume there should be two the going to it the front, and the rear mech?

jpj84

There should only be one cable to the battery. Then there's a junction box - tiny little lego brick thing, which just has four ports:- to the battery, front mech, rear mech, and front junction respectively. This box usually lives somewhere near the bb inside the frame.

It sounds like the cable to the fm had been detached from this junction box - should be as simple as clicking it back into place: there's a very distinct click with di2 cables. Of course, you'll need to remove the cranks to get at it.

focuz

Thanks for that.

Ah okay that makes sense, was just surprised as I’ve only just gotten it and was working the other day.
Thought it was the battery cable disconnected as there was a di2 connector plastic connector end in one of the spare holes in the battery ports but no cable!

Off to the bike shop I go…

BetterShifting_Terry

On R8100, there should indeed be two wires going into the battery.

R8100 doesn't use any junction boxes (unless you're on a rim brake setup), and the battery has three ports.
Also, all three ports MUST be used. Either by a wire, or a dummy plug. If they're not, the system will probably not work.
Finally... a wire should be plugged into the 'center'/middle port.

jpj84

Every day's a school day - I retract my advice, and deign to someone who's evidently a bit more clued up than me (in my defence, the last Di2 I used was 6800)

focuz

BetterShifting_Terry said:

On R8100, there should indeed be two wires going into the battery.

R8100 doesn't use any junction boxes (unless you're on a rim brake setup), and the battery has three ports.
Also, all three ports MUST be used. Either by a wire, or a dummy plug. If they're not, the system will probably not work.
Finally... a wire should be plugged into the 'center'/middle port.

Ah okay thanks, yeah noticed the battery has 3 ports now instead of the one on the last gen. There’s one wire from the bottom plugged in and one dummy plug in place. The other port is free.

So do I need another dummy plug, or am I missing another wire into the battery?

BetterShifting_Terry

Yeah.. you're missing a wire - it's probably somewhere down the seatpost/tube
(One wire for each derailleur)