Originally Posted by
fietsbob
but.. sewn Nylon fabrics needle holes let moisture in adding the rain cover would help ..
(+ elastic cord mounts bounce off racks .. Unless those rail hooks lock shut)
though this combination: a seatpost beam rack, + a pack you slide a pocket in it, over the rack,... is interesting
Backpack - Randonneur Rack
Does not leak in my experience. It's a backpack and a pannier. No extra parts to put on and take off to change it from one to the other. That doesn't work too well when going from walking to having to put the bike on a bus rack (for example). Arkel Bug comes off the rack, you peel open one of the strap covers and it's over your shoulder while you wrangle your bike.
Rail hooks lock shut, they are cam locks. The only way you can get it off is if you open the cams. You don't have to use the shock cord if you don't want to, you can remove it. FWIW, Arkel makes a number of products that have only the rail cams and no elastic cord. Also works fine.
I have a number of Ortleib products as well. When it comes to convertible backpack/panniers, this one is the winner.
J.