Originally Posted by
gerv
I've been thinking about trying some commutes with backpack on a bike that doesn't have a rack.
My only reservation is that my pannier load is 12 pounds, including a stout lunch. That seems quite a load on your back.
I've been using various types of backpacks all my life, not only for cycling but also for hiking.
My back and shoulders are used to it and I never get any pain or discomfort. Also not all backpacks are created equal, some are more comfortable then others, there are cycling specific backpacks which offer a little more comfort but they are not necessary, as a good hiking pack will also provide comfort. One thing which you can not avoid when using backpacks is sweaty back, it's just something that you will need to live with and get used to it.
Messenger bags are not as comfortable as backpacks but I like using them for doing short grocery runs, I can stuff a lot of groceries inside a large messenger bag.