Yes you will need a frame rack on your bike.

I am of a mind that I should buy it once, so
I bought a Tubus rack and Ortlieb bags.
They do and hold more than I need, yet it's nice to know you can carry more if need be.
Sorry no pics of this setup.

Another thing to think about would be a Longflap bag.
Caradice makes a great one.
This along with the rack clamps to your seat rails.
It holds a LOT of stuff!

pics of longflap!