i'm 260lbs and on my Specialized Expedition Sport my front tire depresses a little once i get on the bike and start riding. I had taken it out of the bike shop after putting stuff on the bike, they had the tires aired just right they said. it was only a day or two later that I start to notice the depression. The depression doesn't seem to be getting worse, but i do think about it, since its visable from up above. i did not invest $40 in a bike pump i know soon I will have to.