It depends on what you mean by a "big ride." If it's just a long ride that I plan to do at an easy pace, I can replenish on the road. I'd only do anything special nutritionally before a high-intensity event like a road race or gran fondo. I'll carb load before a full marathon, but not a half.

The latest I've been reading is that it's best to fat load first starting five days before your event, then deplete your body's glycogen and replenish it fully one or two days before the event.