Rider is 5'8, which is than the average for males. Her overall design gives off the impression that she's much taller though.
Truth be told many of the human characters of FSN are surprisingly short. Maybe it's because they're all still teenagers but still...
I mean look at Shirou for example who is 167cm tall or Rin who is 159cm tall. That's like 5 feet 5 3/4 inches and 5 feet 2 something inches. Japanese are generally short.
NNescio said: Iskandar has enough Magic Cancellation magic resistance to prevent the auto-petrify, right?
According to the Type-Moon wiki, you need a Rank A Mana to avoid being affected by Cybele, Mystic Eyes of Petrification. Izkandar is C Rank in Mana and would be petrified immediately. He also has D Rank in Magic Resistance ("Cancel Single-Action Spells").