Get everyone on STW to ride their local loop on a 26″ or 29″ bike and report back the distance, time and wheel diameter. Correlate the results and there is the final and definitive answer.
.. you’ll find there is no definate answer and the wider the test sample the wider the result range.
Mountain biking is far too variable to be able to say that a bigger wheel = faster. In some cases yes, but not all. I’ve not seen a convincing study done yet, they all have too many ‘constants’ attempting to be good test method that in fact constantly skew the results.
The one thing I have read into the tests is that 29ers can have less variance in speed, ie a more constant rolling / average speed. That can ‘feel’ faster to some. But, that average speed is only higher than a 26″ on certain courses. We ride for fun though mainly, so whatever you like the feel of, ride it.
Anyway, back to big companies 29/26 product mix, not what’s ‘better’ –