Erm, what's the point of this ? Everybody on the forum, and every shuttle manufacturer knows that choice of shuttle is temperature dependant. What confuses me with this ad. is that Yonex are using a 1 to 7 scale whereas most players/manufacturers relate to 76/77/78/79 or the 40's/50's speed scale. Why use another system to confuse people ??? 'Wow' indeed.
isn't it the responsiblity of IBF to decide on this, or Yonex thinks they are important enough so that everyone will follow them?
I think Yonex probably wants to have a numbering system for both feathers and plastics. Anyway, the feathers numbering system used by Yonex may not be so accurate. For example I use Yonex AS-50 for testing/evaluation extensively for comparative purposes and I find their speed 2 is actually more suitable for a temperature of 25 degrees C, RH 50% and maybe a bit fast. The chart says differently and seems to be tailored to women or players who cannot hit well. I would rate the Yonex AS-50 as similar to speed 78.