Even though this may cost me reputation of a normal person, to really prove this 1 second you'd need to do the following:
- Measure a hell of a lot timings with the same rider, tyres, weather, and other factors on the same track, with 26 inch wheels.
- Measure the same but with 650b wheels.
Do a couple of statistical tests and then try to make any conclusions. Based on my experience proving 0.35% increase in speed may be very, very, veeeeery difficult If possible at all
BTW, while on this topic, why one can be sure that it's the bigger wheels and not the totally new (from what I can see) carbon frame?
Ahhh, analytics... :)