I spent some time making my own seatpack based on the industry standards and came up with the below. I used 1000d cordura on the high wear/abrasion areas and 500d on the extremities. I think next time I might go a bit lighter but as it stands the bag is no dog. If anyone is interested I can take some pictures of the patterns that I made.
I test fitted it today and located some weak stitches and the like but in all it came together really well.
Does anyones bags interfere with the inner thigh? I have some light interference that worries me a bit. I'll have to get it on the trail to see how it feels in action but anything that rubs the skin for hundreds of miles is going to be an issue.
How much sway do you guys get from side to side? I am thinking that a third strap around the seatpost might be necessary to lock it down a bit better.
Successes:
- Creating daisy-chain webbing on the top for multiple seat-rail lashing points helped in getting the vertical angle fit right.
- The fabric and materials worked together very well.
- The size and fit on the bike was good except for the girth near the seatpost. I would guess the capacity to be around 10-12 litres.
- Sewing machine worked the part with denim needle and some care on thicker areas. I used an older brother home machine. It is made from heavy cast iron which helps keeping things in line on denser materials.
Alterations for 2.0:
- Addition of third strap on seatpost
- Continuing the 1000d layer further back on the bottom for splash/kick-ups from the tire
- Addition of an internal compression strap mid-way through to help in the fit
- Adjusting the girth near the seatpost. I still might bring in that seam to correct for leg rub
All in all a success! Let me know if you would like any additional pictures of specific areas.