I have a friend looking for a used mtn bike so she can get some mtn biking on trails in as well as some scooting around town with her kids. She's 5' 4" and has budgeted $400. I know this is a little low for a decent bike, but putting the word out there. Anyone need to make room in the stable? I'd say at 5' 4" she's going to need a small frame if 26" wheels (I take a medium and I'm 5' 6"), or x-small for larger wheels. I could be guessing wrong, but that's what I'm thinking.