bathoutdoors.co.uk has used the Blackburn Outpost Bikepacking bags for years now and believe they are one the best systems for people getting into bikepacking.
Blackburn says - Keys, check. wallet, check. energy bars, check. hydration bladder, check. The Outpost frame bag is the perfect companion for your all day pleasure ride or your week-long adventure ride. An expandable bottom compartment accommodates more mission critical gear.
This size large is perfect for bikes 19" or 58cm & above. if in doubt please contact the store for advice.
• Expands to fit a wide variety of frames and sizes
• Simple to install and remove
• Highly water resistant
• Interior organisation and exterior slip pockets
• Includes hydration tube port