I've started cycling (learned to cycle as a kid but never really did it more than once a week) to lose weight. I've been using a family friend's folding bike and a bike sharing app. I also just got a brand new bike today (yay!) but haven't taken it out for a spin yet. While using the folding bike and bike sharing app bikes, I find that I will suddenly feel off-balance and veer to one side. Of course, this can be very dangerous, and I'm putting my plans to join cycling groups on hold because I might crash into to other cyclists if I don't figure out how to stop doing this. Any tips or advice? Since this has happened on different bikes, it must be me, not the bikes.