After not having owned a backpack for nearly a decade, I recently bought one - mainly for nature walks, which I hope to do more of. The backpack is on the small side, lightweight, with lightly padded adjustable straps. I do not know much about backpacks, but this one is very comfortable for walking and it is waterproof.
Of course having gotten the bag, I was immediately tempted to wear it on bikes that have no provisions for carrying loads. It was fun at first, but now that the novelty has worn off here are some notes:
. I can feel the weight on my back. When I move around on the bike the weight inside the bag shifts and affects my balance.
. The straps rest a little too heavily on my shoulders and their width constrains movement. (Interestingly, I have tried a few cycling-specific backpacks in the store and their straps are even wider - I can hardly move my arms.)
. On an upright bike, it feels as if the weight of the bag pulls me backward a bit.
. On a roadbike, despite being small the bag obscures my vision as I check behind me for cars.
. Each time I have worn the backpack on a bike, my back was drenched in sweat afterward.
. These things notwithstanding, having tried riding with messenger-style bags when I first began cycling, I definitely prefer the backpack. It feels more secure and stable. I've never been able to get a messenger bag to really stay put on my back, even when it's a bicycle-specific design.
In a pinch having a backpack is great, because it makes it possible to carry a load on any bicycle without requiring the presence of racks, baskets or panniers. But if given a choice, I would rather attach things to the bike itself.
On a separate note, I wonder whether there have been attempts to make a backpack for road cyclists to run errands on their way home from a ride. It would fold up tiny, fitting into a jersey pocket like a musette bag but expanding into a large rucksack. It could then be filled with groceries on the way home and would be fine to wear for just the last mile or so. I sometimes wish I could stop by the store on my way home from a ride, without having to switch to my transport bike first. Of course, there is also the issue if locking up the bike...
What has been your experience cycling with a backpack?