It's an interesting if impractical idea. Why can't they put the filtration technology on the water pump for everyone to use and use normal bikes? This is 3rd world 'keeping up with the joneses' if you ask me. What next, a barbecue bike that roasts an ibex by the time you're home much to the envy of the next hut?
Nice idea, demonstrating another aspect of life I take for granted. A critical factor would be the terrain though...
Given that a litre of water weighs a 1kg, moving and stopping all that mass would be one way of building muscle! Cornering might be interesting too...
