Ok, former MTB'er here, I have recently gotten a cross bike. I am now riding a lot of rural roads and would like a mirror to see approaching trucks, dog's etc. from behind. Pretty sure I don't want a mirror for the bars as I still shred some single track and would bust it off on a tree. Started my search on Amazon and there are a ton, so I'll ask you, what do you use? Also would like to keep it aroung $20 if possible. Thanks