The front wheels collapses into the frame with every use. Our little Cavalier King Charles Spaniel topples over if we don't lean the bag against a wall or other supportive surface. I love the large size, my only gripe is the two front unreliable wheels, but balance is important when transporting dogs inside carriers. We want them to feel safe and secure. I don't see another bag that's a good size like this one, so I guess I'm stuck with it for now. We've used it everyday for almost three weeks now, so we've adapted to the defect.