I'm sure I'm not the first person to discover this product but have been really impressed with it over the last month:
http://www.amazon.co.uk/Pacsafe-StuffSafe-Waterproof-Secure-Stuffsack/dp/B000YOLDZS
Basically I got one because I commute to a railway station and have to leave all my gear on my bike. Luckily Santa brought me a pair of Sidi Adventures for Xmas which are great but don't really fit in the system panniers (1150gsa) that easily.
From experience it a well made product that I find neatly attaches to the grab handle when not in use and I leave my boots and helmet in it.
A couple of observations:
1. the padlock does not look very substantial so this could be something to change if you feel the need.
2. The dry sack itself could probably be replaced with a canoe type dry bag should it become damaged.
All in all, a good buy.

http://www.amazon.co.uk/Pacsafe-StuffSafe-Waterproof-Secure-Stuffsack/dp/B000YOLDZS
Basically I got one because I commute to a railway station and have to leave all my gear on my bike. Luckily Santa brought me a pair of Sidi Adventures for Xmas which are great but don't really fit in the system panniers (1150gsa) that easily.
From experience it a well made product that I find neatly attaches to the grab handle when not in use and I leave my boots and helmet in it.
A couple of observations:
1. the padlock does not look very substantial so this could be something to change if you feel the need.
2. The dry sack itself could probably be replaced with a canoe type dry bag should it become damaged.
All in all, a good buy.

