Russ Roth

So you're slow and unskilled? How does that relate to someone else's abilities. I grew up in an area where paving consisted of throwing down a layer of oil and covering it with a layer of loose gravel and hoping the cars packed it down. I regularly did over 20mph on that with basic 27x1 1/4 and later 700x23 tires. So does anyone who lives in the area on a yearly basis.

OP, the trek will give a better result towards your goal. The 7.1fx is a sport hybrid, little lighter and quicker and depending on the mtb could be a lot quicker. You said a schwinn, if a modern, heavy walmart schwinn the trek could be a huge improvement. If an older, shop bike it might not be as big. Personally I would keep an eye out for a lightly used gravel or cross bike from trek, felt, jamis, cannondale or a couple of other brands that offered them in 46 or 47cm. Something like the Caadx tiagra from cannondale can be found 4-5 years old and will be a fine size but should be right in your range. Look up what these brands have offered in the last 5 years and go from there. They will fit someone your GF's size with no trouble. Flat bars on a hybrid like the trek can be fine for an hour or two, past that that add some bar ends or switch up the bars to ones with an extra position or two.

I will agree with you that I think wheel sizes matters to a tiny extent. I know all the numbers sheets say otherwise and I've seen the write ups on why it doesn't but I've watched a dozen kids go from 650c wheels to 700c and they're faster every time. Bikes aren't always better but the kid is still faster and it isn't gearing as all the kids have to pass rollout for racing which is the same regardless of wheel size. Same with the kids that have moved from 24" to 650c. Just always a consistent speed increase. I've noticed that taller seem faster for me as well.