I think most of the difference in geometry is accounted for by the adjustable dropouts on the 19. Download the Whyte brochure as it has the accurate figures, the website itself is prone to throwing up all sorts of strange specs and sizing info. The other day it was suggesting that the 19's came with DT forks for the Ti and SIDS for the ally one. It also throws up incorrect sizing from time to time. The 905 is only 1/2 pound heavier than the 19 which may well be down to the kit rather than the frame.