I have a nice bike bag. But inside it is a Specialized bike box, it’s that which does all the work. Knowing what I know now I wouldn’t buy a bag again, I’d get a good box, laminate it to **** with a mile of packing tape to give it more durability and weather resistance, fashion a couple of handles, and call it good. They slide along the floor better than most bags roll!
Box recommendation- go to Halfords, find an Apollo one. They’re a decent size, and made of some sort of mega-cardboard, very strong. They have to be, they’re for transporting 50 pounds of pig iron round the world on the cheap. My specialized box is for carrying lightweight expensive bikes that get looked after, so it’s way weaker.