Originally Posted by Metaluna

I didn't even realize that the SM-BTC1 had a B junction in it. I thought it was basically just a plastic tube to hold the battery, but if it also replaces that horrible under-BB junction box (SM-JC40), then it's starting to look like a pretty good value (it looks like it might even include an e-tube wire for the battery, so that's another $20 savings). Anyway I'd be amazed if it didn't work with road groups, as I think the B junction just passively wires all the ports together and doesn't care what kind of packets are being sent over the CAN bus. The other junction B's (SM-JC40, JC41) are used for both mountain and road, so this should work with both also.

P.S. According to this, the SM-BTC1 is compatible with road and mountain groups. It doesn't specifically list the Ultegra 8000 generation, but from an e-tube point of view, there's no difference.

https://www.bike-discount.de/en/buy/...sm-btc1-220699