Just ordered myself a Waterproof Travel Bag for the bike, mainly to carry Teela's riding gear to National Rally, but also for extra storage when it is just me, it looks pretty good!
Caribee Kokoda 65L
(http://i1222.photobucket.com/albums/dd499/ozstoc/caribeekokoda65l_zpsb4a0a27a.jpg)
Volume 65L/60 x 35 x 35cm
Heavy duty weather proof Caribee PVC tarpaulin barrel bag
#10 water resistant zips
Removable padded shoulder straps convert barrel bag to back pack
Heavy duty 2" webbing encircles the bag for extra strength
End haul handles
Twin QR compression straps
ColoursBlack (58071), Charcoal (58074)