Seat pack dimensions

[hmaddox]

After a somewhat successful MYOG frame bag, I've decided to try my hand at a seat pack. After studying a lot of photos of seat bags by Relevate, etc. I put together a rough design, cut a few pieces of cordura and pinned them together for a mockup. What I found was that the bag seemed too small to hold a significant amount of gear. Based on photos, it looks to me like most professionally-made seat bags are not much wider than the seat (at their widest) and typically don't stretch farther back than 3/4 of the way over the rear tire.

My mockup bag fit these rough dimensions but seems too small to hold a sleep system (30-degree synthetic MH bag and tarp) which was what I wanted to use it for. Is anyone carrying these things in their seat packs or do most people store those on the front end? Would anyone mind sharing the length (rolled and unrolled), width and height of their seat pack? I'd be most grateful!

[T-manTorin]

Hello there Hmaddox,
I came up with a design you might be interested in.  My seatpack measures, 7" high on the seatpost, 25" on top (front to back), 28" on the bottom (front to back), and a 9" opening.  It will collapse to around 8".  When it is full it measures approximately: the front @  7" x 6",  the middle @ 8" diameter, the Back end @ 10" diameter.  Total length when full is around 24".  It's a one piece main bag which offers a waterproof environment, so you don't need to use an addition waterproof stuff sack.  It has a protection cover at the front of the bag for the heavy abrasion areas and strapping areas. 
I have found that having you sleeping kit up front works really well as long as you keep it all no more than 5lbs. After 5lbs my bike gets to hard to control on the front end.  This includes you sleeping bag, pad, and one man bivy.  I also found that I can compress the whole sleeping kit by rolling it all up together really tight which allows you to have a stable pack system.  I have found to that the more stable everything is the more consistent control you have.
I hope this answers some of your questions and helps you out. 
You can check out my Bikepacking Picture gallery @  http://lonemountaininnovations.com/bikepackinggallery/
Take a look around my site and you can view a few of my bag products close up.  I'm not trying to sell you anything but enjoy being on this site to share the journey in all this and learning from each other.
Keep innovating!
 

[syb]

Hello there Hmaddox,
I came up with a design you might be interested in.  My seatpack measures, 7" high on the seatpost, 25" on top (front to back), 28" on the bottom (front to back), and a 9" opening.  It will collapse to around 8".  When it is full it measures approximately: the front @  7" x 6",  the middle @ 8" diameter, the Back end @ 10" diameter.  Total length when full is around 24".  It's a one piece main bag which offers a waterproof environment, so you don't need to use an addition waterproof stuff sack.  It has a protection cover at the front of the bag for the heavy abrasion areas and strapping areas. 
I have found that having you sleeping kit up front works really well as long as you keep it all no more than 5lbs. After 5lbs my bike gets to hard to control on the front end.  This includes you sleeping bag, pad, and one man bivy.  I also found that I can compress the whole sleeping kit by rolling it all up together really tight which allows you to have a stable pack system.  I have found to that the more stable everything is the more consistent control you have.
I hope this answers some of your questions and helps you out. 
You can check out my Bikepacking Picture gallery @  http://lonemountaininnovations.com/bikepackinggallery/
Take a look around my site and you can view a few of my bag products close up.  I'm not trying to sell you anything but enjoy being on this site to share the journey in all this and learning from each other.
Keep innovating!
 

As a noob to both this site and bikepacking in general, I really appreciate your dimensions and willingness to help out.  I'll be doing some DIY seat packs thanks to this post.

Syb