Originally Posted by zonatandem

Most tandems are set up, and sold, with in-phase crank setup.
That does not mean you can't change that!
Suggest you try riding out-of-phase (OOP) for a few weeks and then decide which method you prefer.
We are proponents of 90 degrees OOP and have pedaled that way for 30+ years.
Easy to change over from in- to out-of-phase. The 'correct' way is to loosen the eccentric and put crankarms in the position you desire. Then re-tighten eccentric.
However, there's a shortcut that works a bit faster that we utilize.
Utilizing a workstand or have partner hold up rear end of the bike:
Spin the cranks backwards, derail that crossover chain with a small bladed screw driver. Set-up the crankarms OOP by as many degrees as you want, with either pilot or stoker leading (your preference).
Put chain back on by spinning cranks forward.
Now go ride!
Pedal on TWOgether (OOP!)
Rudy and Kay/zonatandem