Chris C wrote:

I was fitted for a road bike (specialized
sequoia) yesterday. The man at the
shop told me a 54cm was right for me (he
was the same height as me) , the
56cm felt stretched out. He told me it's a
compact frame. Is this going to
be my size if I was to buy a used bike off
ebay and does a compact frame
make a difference for the sizing ? I am 5' 11" .

If this is your first road bike you may feel stretched out at first.
Buy there's much more to fit than a "frame size." For one thing two
different "54 cm" bikes may be VERY different. Your height is only part
of the story. More important are leg length, arm length, and torso
length. Not to mention your flexibility and type of riding. If it
doesn't feel right to you, something's probably wrong. To some extent,
fit can be accomplished by chainging the stem height and reach.

See:
http://sheldonbrown.com/frame-sizing.html

If you're not sure that a 54cm bike feels right in person, I certainly
wouldn't recommend you buy one on eBay!

Art Harris