RC: I have and will conctinue to make the point that the origin of both 26 and 29 inch wheels was a matter of convienience--not science. 2 x 1.75-inch whees were the only alternative that wold work with the components available when mountain bikes were "invented." Hub withs, bottom bracket and crank designs would nbot support  700C or even a 650B format. Wider hubs and dirt-specific drivetrains now make larger whels possible, but we chose a conventional 700C road bike wheel to base 29ers from--again, because it existed. Are 29ers best? is the 26-inch format valid? Is 650B (another off-the-shelf wheel) best? Now that off-road cycling is established, we owe it to ourselves to evaluate the best wheel-diameter compromise that will fit into all modes of the sport--XC racing to long-travel gravity stuff. Science, not religious fervor should make the call this time.

 

The limitations of 29 inch wheels are especially troublesome when suspension travel exceeds 5 inches. At this point, the mid-sized 650B allows more tire clearance, bigger tires and lighter wheels--all of which play well to the needs of the medium-travel trailbike as well as the downhill bike set.   

 

That said, Trek and Specalized are at war with each other at present to establish themselves as the inventors and leaders of the 29-inch movement. With the full force of the two big-brand's marketing departments (and also their buying power) focused on 29ers, there is little hope of any other wheel format taking hold until the limitations of 29ers have run their course. Once that has happened, Trek and Specialized's design groups will no-doubt fly the alternative-wheel diameter flag as their own.