Originally Posted by
wphamilton
Saddle dimensions are not necessarily all the same. The tip maybe closer or further from where you sit....
So I don't see how that method could possibly work, other than by accident, for setting reach. It might be helpful for checking whether the bike size is in the general ballpark.
+1
I've run a piece of string over the saddle, to help pinpoint where my sit bones go. Then I use that instead of saddle tip when trying to recreate a known working position on a new bike.