Despite the fact I have packed lightly, my hiking backpack is not quite small enough to carry on. So, I have to check it, but I’m worried that the straps and buckles might get caught on things. Does anyone have any suggestions for ways to protect the bag?

Someone suggested using a duffel bag, but then that negates the purpose of a hiking backpack since then you have to carry the duffel bag around Europe. Does anyone have any other suggestions? I was thinking maybe I could just drop the hiking backpack into a trash bag or two (those are light and can be carried throughout europe), so I could protect the bag on the way there and back.