I am looking into getting into cyclo-cross, and I have been looking for either a complete bike or just a frame, but so far for I have noticed is the frames are huge!!! I am only 5'6" and ride a 52cm Felt with a standover of about 735mm, I was looking into getting a Redline, and so I was looking at a 52cm (thinking that they where all the same size) and the standover height was something around 780mm (it is not just Redline that I noticed this on) and if I am going to have to get off this bike to clear barriers I would like to do it with injury

should I looking into a 50cm on all brands?

so why is the difference so great? does it have to do with the higher bb?

how much "clearance" should I have?

Do then make cyclocross bikes that will be small enough for me?

Can any suggest a company that might make a frame that will be small enough?