Bikepacking Saddlebag Specialized Epic Dyneema

When a 250 mile bikepacking trip falls in your lap, the answer is yes, even if you only have 2 weeks to design, develop and create an entire bike bag system for your XC MTB.

With such a tight deadline, it was important to be efficient and extremely prepared before starting the final designs to avoid costly mistakes and/or failures in the process.  Taking the time research properly bring to light what is most important in the final design. Also, ordering all needed supplies is the most important piece…obviously.

After a few days of research, I laid out my goals for the bags:
-Shape must keep bag from rubbing the back of my legs while pedaling
-Waterproof/resistant construction
-Reduce/remove the swaying left and right while pedaling (especially noticeable while climbing out of the saddle)
-Bag must perform when filled to capacity and when carrying smaller loads.
-External shock cord attachments for drying and bulky items
-Stuff sack to easily remove contents while bag is still attached to the bike
-Reflective and light attachment points

Surprisingly none of the bags I found had all of these features in one product. I thought about one of my favorite quotes, “recognizing the need is the primary condition for design” (Charles Eames) and got to work.

The Details:
To keep the shape narrow enough to prevent rubbing, I kept the width of the top/front panel to a minimum at the seat post and flared the seam to match the width of the saddle rails, then extended the top shape to be half of the opening.


To achieve the best water resistance, I utilized one seam construction. The bottom is LS07 with a 5oz Dyneema patch for the attachment points and for added structure.  I seam sealed the bottom patch stitching on the inside of the bag to keep it waterproof.

The top panel is more complicated as it comes in direct contact with the bike and needs to provide the foundation for stabilizing the rest of the bag.  To prevent abrasion/fabric damage I used the 5oz Dyneema for the areas that would be in direct contact with the seat post, collar, and saddle.

To create structure and stability I backed the top 5oz Dyneema panel with a layer of 2mm closed cell foam and a flexible sheet of plastic. To attach the bag to the saddle rails I used the 5oz Dyneema.  The assembly of 5oz Dyneema, 2mm foam, and plastic was then applied to the top layer of white TX07 that extends in one continuous piece from the front to the back opening to keep a continuous layer of waterproof fabric. This extra structure prevented the bag from swaying.

To attach the bag to the seat post I used a series of three attachment points using plastic tri-glides attached to 3/4″ webbing that pass through a 1″ plastic rectangle attached to the bag with x-pac fabric. This fabric attachment is necessary to reduce bulk to allow the tri-glide to easily pass through the rectangle opening. I really like this attachment method because it’s light weight, compact, easy to use and can cinch down very tight.


I engineered the attachment points to create the most stability of the bag for 50% – 100% capacities.  The bag attaches to the saddle rails with heavy duty 1” poly webbing that is sewn to the 5oz Dyneema patch on the bottom with Dyneema extensions which reduce bulk and weight.  The webbing is then threaded through a 1” rectangle that is attached to the top seam of the bag with 5oz Dyneema. The webbing is then threaded through 1″ ladder-locks on the bottom.  There are two options of ladder-locks sewn onto the bottom panel depending on the size of load being carried by the bag.

The webbing was too thick to pass through the ladder locks when it was doubled and bar-tacked so I created end caps using 5oz Dyneema to facilitate threading the webbing through all of the attachment points and to keep the ends from unraveling.



The opening closure is reinforced with 1” camo poly webbing on the outside and Velcro on the inside.  I made the closure with ladder locks so the V-shaped stabilizer straps could be attached and cinched tight after being threaded through from the top and bottom.  The ladder locks are applied to the webbing with white x-pac fabric to avoid destroying the webbing if I decided to change to a side release buckle after testing.  I don’t recommend applying the buckles to the webbing as it reduced the opening size and some of the stitches popped while I was overstuffing the bag.  Next time I will use J-hooks and some version of side release buckles.

While looking for the perfect place to attach a rear taillight and reflector I noticed the V-shaped stabilizing webbing at the back was not as secure as possible and would be improved by connecting the two together in the middle. Luckily had a couple 1” sternum strap slides in my stash of hardware that I attached together with a small piece of 1” webbing, then added the strip of reflective fabric leaving just enough space to attach my taillight.

When I made the pattern I didn’t know exactly where I would need shock cord on the top for carrying at both 50% and 100% capacities so I added extra cord attachment points for on the fly adjustments.  I used a shock cord with reflective flecks for added safety and the red color to match the red taillight and other red accents on the bike itself.


This bag carried my sleep system so I needed it to be waterproof and removable. This was imperative since we set up and broke down camp in the rain three times.  In order to make use of the entire shape of the main bag I created the same shape for the stuff sack using .5oz Dyneema.  I used the Dyneema adhesive tape to seal the seams and made the closure with 1.5mm sterling accessory cord and a micro cord lock.

A fun first adventure using this system – a lot learned, and a lot of fun.

Fabric Details
5.0 oz Dyneema® Composite Fabric Hybrid CT9HK.18/wov.6 is a 2-layer laminate material using 2.15 oz/yd DCF for the inner layer and a 150D polyester plain-weave face fabric
Content 15% Dyneema fiber / ~65% Polyester / ~20%Other Polymer Film
Weight 5.0 oz/sg yd
Tear Strength warp 68 lb / weft 55 lb
Made in the USA

Weight 3.2 oz/sg yd
Tear Strength 7.9 lb
Waterproof 100 psi
70 denier ripstop Nylon
0.25 mil PET film
Made in the USA

LiteSkin LS07
Non-Woven Polyester face coated with Poly Resin
70d Nylon Ripstop c6 DWR
Weight 3.4 oz/yd 2
53% Nylon 47% Polyester
Waterproof 160 psi
Made in the USA

.51 oz Dyneema® Composite Fabric Composite
Content 35% Dyneema fiber / 65% other polymer film
Weight .51 oz/sg yd
Tear Strength warp 14 lb / weft 14 lb
Made in the USA