we know the yanks like a nice stat
Niner did some studies btw comparing descending speeds of 29er and 27.5 all mountain Bikes. The venue was the lift-assisted trails of Keystone Bike Park in Colorado. This is a true all mountain course with chunky rocks and raucous descents. Of course the source may be biased given that Niner is a 29-inch wheel sized only company. But we don’t doubt their general findings that in these conditions, a well designed 29er is faster.
niner might be slightly biased though!