So in other words - its a Crock anyway you look at it. Old timing methods folding into new timing methods…
The Best maths would be to look at the Current BASIC times.
Beijing = 9.69 x 2 = 19.38 - however, we know he slowed down in the 100m, so a 19.30 would be about right.
Berlin = 9.58 x 2 = 19.16 (pretty darn close)
This is what we know he can and has run. Usains maths is simple - double the current 100m.
Im sorry, but all this talk about Predicting a sub 19sec run, is akin to talking about a 9.58 with a 2mtr tail wind, raced in altitude, raced on a B track instead of a A track, wearing a new swimming suit and running a 9.42…
Not saying a sub 19 wont be done, but Usains 200m Maths is in - double his current 100m