Originally Posted by
AdamDZ
A word on waterproof panniers. I don't know exactly what Arkel had to say about waterproof panniers, but for commuting and short errands they work well. I have a set of Axiom waterproof panniers and I don't need to worry about forgetting the covers or having to pull over in traffic to put the covers on.
For longer use, however, like touring I wouldn't use them. Hot weather, ouch

They're fine up to like 1h maybe and then they get really hot inside, and outside too btw, there is no ventilation at all.
Here is what Arkel say about waterproof bags, they're not dismissing them but they do point out that condensation can be an issue and that would leave the bag's contents damp, something I hadn't thought of when considering the Ortlieb Back Rollers or Vario bags.