Hi,
to get a little bit more room for my stuff and to level out the weight distribution when driving with the seatpost-bag
http://www.bikepacking.net/forum/diy-make-your-own-gear-(myog)/diy-seatpost-bag-waterproof-lightweight-trail-worthy/, I started a toptube-bag.
The idea: a flat waterproof bag with a roll closure hanging over the toptube directly behind the steerer tube, attached with straps.
I found an old flat Ortlieb-Bag, purchased a bit of PVC-canvas, some straps and closures. From the canvas I cut some 7x7cm pieces with two slots to thread the straps through, and glued them to the bag. One strap is going horizontally around the steerer tube, (closures in front of the steerer and behind the bag between top and downtube), one is going vertically around the middle of the bag (one closure on the side) and a third one going diagonally under the downtube to keep the bag away from the fork.
After a first testride the attachment works pretty well with no wobbling. But the problem with the ortlieb-style roll closure (trapped air inside the bag will "inflate" the bag while closing) is made worse by "bending" the bag over the toptube, so the bag touches the inside of your knees when riding out of the saddle on very steep uphills. So I took an old inner tube and glued the presta valve to the bag to have the possibility to deflate the bag while fastening the straps. I hope it works (glue is still drying).
Bye, Kai
