Our All-Rounders vary from 43cm to 46cm. It's also fair to say we belive low bottom brackets have a tremendously positive affect on how a bike tilts and turns and descends. Bottom bracket height is determined by the frame's bottom bracket shell's position relative to the centerline of the dropouts, and the wheel radius. Most road frame drops are between 68mm and 70mm. Ours are 80mm.
Nobody makes a frame with more drop than that.
No high-volume production bikes go to 80, for reasons too complicated to go into here. We're most comfortable, and we believe most people are most comfortable, when the bump just below your knee is well behind the pedal axle. If you like steep seat tube angles, don't order a Rivendell, because custom or not, we won't build it. Our bikes feel pretty neutral. They feel as good at 12 mph as they do at 55 mph.