I carry most of my valuables such as camera gear in my tank bag as I can easily take this with me (the shoulder strap is invaluable).
This type of tank bag mounts to a special ring mount around the fuel filler and stands proud of the tank paintwork,
Here;s a picture of the attachment ring on the bottom. Obviously you need to be able to remove it quickly to fill the fuel tank, the red release lever allows this.
In case the ring should ever fail there is a safety strap which I attach through the sat nav mounting bracket
Safety strap attached to sat nav bracket.
If (when) it pours with rain there is a bright yellow waterproof cover (for visibility to other traffic in poor conditions).
