I want to get a folding bike because I travel frequently by air and would like to continue exercising while I'm away from home. I'm a road rider and my average pace on rides is 19 mph. I've seen a lot of high performance folders, but they are way out of my price range. While I'm not looking for the same performance and speed as my regular bike, I am looking for similar feel and effort. I just want to be able to have a good workout, speed is not my primary concern. I'd appreciate any suggestions.