It has been years since I rode a bike, mostly because with a three year old and one year old I had no means to take them along. I was recently given a bike trailer and was excited to get them all hitched up. MY GOD it was HARD! I'm hoping it was just pulling the two kids. I am going to try a run on my own. The bike I used was actually left here by the previous owners when we moved in and the tires were flat. I got air into them but maybe it would be worth taking it in to be looked at? I know little about cycling. Any tips would be awesome.