Two Chainrings on a Rear Wheel

From Sheldon Brown (of course):
Bruce Ingle, a fellow member of the Charles River Wheelmen, has gone me one better, and made a triple-fixed mountain bike. He used a Shimano cassette hub, which he immobilized by brazing the ratchet mechanism together. I am a bit nervous as to the long-term prospects for this hub, in particular the connection between the freehub body and the hub shell, but I think I will have to copy his setup. He's got:

        Gain    Inches    Meters    
48/20    Fixed    4.65    62.4    4.99
42/26    Fixed    3.13    42    3.36
36/32    Fixed    2.18    29.3    2.3

(http://sheldonbrown.com/singlespeed.html)

Triple front ring, triple rear, but always with the same overall number of teeth for each ratio, so same chain length.