If the cake is too cool when you try to roll it, it will likely crack. That is why it is important to roll it in the sugared towel when it is fresh from the oven. Roll and unroll it gently as it is such a thin cake layer. If you do have a slight crack or tear in the cake, just keep rolling! It will likely not be noticeable at all as this is a forgiving cake design. Especially when the cake is frosted!