Are bicycle rear racks and panniers suitable for cross-country riding? Later this summer, I intend to make a ten-day travel. It is going to be mainly road touring with one-two-tree days of sloped dirt roads or forest trails possible.

I usually pack heavily, carrying a 60 litre pack, that I will probably fill up for this journey (tent, sleeping bag, beer will be restocked continuously). Both the backpack and bags have rain covers. However, my concern is that putting around 10 kg(22 lb), maybe 15kg(33 lb) directly over my rear wheel will ruin the rim at the first hole I bump.  Which should I choose : the backpack or the system of rear rack mounted bags system? 




Related: Why do cyclists prefer messenger bags over backpacks?
Gary Fisher Kaitai suffers from handlebar wobble at moderate speed with 10lbs on rear rack
I'm a member of Warm Showers, and regularly host cross-country bike tourists and get to check out their gear. Except for the occasional monk with orange robes and a small backpack, what bike tourists choose has been surprisingly uniform. 

It's usefully Ortlieb panniers on front and rear racks, and sometimes a handlebar bag. The details and presence of the handlebar bags vary some, but the choice and use of Ortlieb panniers has been a near constant. I don't own any yet, but I suspect they are chosen because they are waterproof and durable-- two key qualities for a long distance trip!

Here are a couple sample photos of bike tourists I've hosted (both with Ortlieb panniers)





I would add: don't worry about the weight-- with a proper rack, bike tourists sometimes carry 50 to 80 pounds of gear, much of it on the rear wheel.