Originally Posted by twocicle

For the road tandem we use a 11spd triple XTR Di2 derailleur setup with a SGS rear cage, 48/36/26 rings x usually a 11-28 cassette for typically hilly stuff or a slightly closer 11-25 for cruising. These are our go-to close ratio cassettes and the rings are on a 104/64 mtb triple spider. For comparison, the 26x28 combo is a slightly lower ratio than a 30x32. We have a 11-36 cassette ready to pounce on any unsuspecting climb which thinks it is steep enough to warrant it, but we typically hate the bigger ratio jumps on this kind of cassette and so only resort to it for seriously hard day to day tours when fatigue will be a factor.

Obviously a 48x11 is by far not a big enough gear for racing, but IMO (and we have never been dropped) plenty for high spirited riding. My advise to everyone is to get gearing you can use all the time, not what you wish you could use.