I also belong to the triples for mountain bikes and doubles for road bikes camp, although I have also enjoyed the third-step (49-46-43/13-16-19-23-26) and half-step-plus-granny (48-45-34/13-15-17-19-21-23) road setups I have used in the past.
It depends on how much range you need, how high a top gear and how low a bottom gear. I simplify the problem greatly by topping out in the mid-90s (93 to 98 gear-inches on the four road bikes) and bottoming in the low-mid 40s (43 or 44, although the Sieger does have a hardware-constrained higher-than-ideal low of 47 inches). The road bikes each get a 2x6, with either half-step or 1.5-step, but the mountain bike does have a 3x8 1.5-step-plus-granny (48-40-24/12-13-15-17-19-22-25-28).
I saw the 14-speed Rohloff IGH mentioned, but the ratio step is a bit larger than my preferred 6 or 7 percent.
__________________
"Far and away the best prize that life offers is the chance to work hard at work worth doing." --Theodore Roosevelt
Capo: 1959 Modell Campagnolo, S/N 40324; 1960 Sieger (2), S/N 42624, 42597
Carlton: 1962 Franco Suisse, S/N K7911
Peugeot: 1970 UO-8, S/N 0010468
Bianchi: 1982 Campione d'Italia, S/N 1.M9914
Schwinn: 1988 Project KOM-10, S/N F804069
Last edited by John E; 12-22-15 at 12:55 PM.