Just had to get these filled up with stuff and haul myself up the nearest hill to try them out. It's an Epic Designs frame bag and fuel tank - for fig rolls not petrol silly. They were actually ordered to fit my Karate Monkey but they happily fit the 1x1 (x8) just fine too. Once I'd adjusted my swinging baggy pants with the velcro straps there was absolutely no rubbage when pedalling. Got all my usual ride stuff in plus a JetBoil, insulated cup, spare gas (why?) and some soup - yum.
Loads of room to spare. I could tell because of all the rattling on the way back down the hill. None of it inteferes with any of the handling - it's all low slung and incredibly stable. Fantastically bivy-tastic.