I live in Wisconsin, the weather can vary a lot, so in the morning it may be 50, in the afternoon it may be 80. I already have a saddlebag on there, with the tools and tubes etc. The bigger bag in question would mostly be used to carry extra clothes, a camera, maybe a lunch in some of my rides go into the boonies. The size of that bag seems just about perfect, however the real question is whether it is safe to mount on carbon. Thanks for your input guys!