Justin Bieber & Selena Gomez -- The Couple that Segways Together ...

Justin Bieber and Selena Gomez have segued from separate to together ... at least for the afternoon.

Take a look at this pic. Our Calabasas spies tell us Justin and Selena were just spotted tooling around The Oaks -- where Justin lives -- on their Segways.

The two haven't been spotted together for months, and it seemed Selena was done with him.

Justin is clearly showing her who's boss ... leaving Selena in the dust at a mighty 12 MPH.