hey everyone i could use a little direction. i do plan on going to my local bike shop but the more advice the better right. so my first bike, i also wanna get 1 for my girlfriend. couple points i wanna hit. is used just a horrible idea ? also theirs a concrete trail near us i wanna ride but i do want a bike i can get on some real trails with. is this an issue in regards to tires? from what ive read it seems like i wanna spend 300-600 any bike suggestions in this range? those and any advice when it comes to getting started in the sport would be greatly appreciated.