Quickbeam
I have looked at the bike and it probably makes more sense as a single speed with 2/4 options of gearing with a freewheel on each side of the flip flop, rather than fixed due to the less than straight chain line when you run two front chain rings. If that is the case, it seems like a solution in search of a problem. Why not just ride a multi geared bike and save all the trouble of flipping the rear wheel/adjusting the chain on the front chain wheel. Just my 2 cents. If you run it with just one chain ring on the front then it becomes a rather elegant single speed/fixed gear although a pricey one. I like Grant Peterson at Rivendell, but I think he over engineered this one in attempt to catch the wave of interest in fixed/ss biking that is currently afoot.
fixedgearhead