Bikepacking Seatbags – The J.Paks SeatPak

by Andy Amick on May 22, 2013

in Bikepacking, Gear

The seat bag, frame bag, and handlebar bag are the three main bags used for carrying gear on the bike for bikepacking.  A few months ago, I decided to finally buy a seat bag to replace my homemade coroplast bags.

Since local companies are important to me, my choice came down to J.Paks and Bedrock, which are both made in Colorado.  They each make some really nice bags, but I decided to go with J.Paks because I had already purchased a bag from Joe and the quality and customer service were exceptional.

Handmade bikepacking bags from J.Paks

Bag Details

SeatPak has an upward slope that works for full suspension bikepackingOverall volume of the bag is listed at 6-14L.  At a fully extended 14L, the bag is almost as long as my arm and it will store a whole lot of gear.

The SeatPak is made with a combination of 1000D Cordura for the main body and 420D nylon for the last 6″-8″ section of the roll bag opening.  I don’t know the specifics of the multiple materials, but the nylon does roll down better than the thicker Cordura material.

I asked Joe about the bag being waterproof and he mentioned that it’s highly water resistant but not fully waterproof.  If you are worried about items getting wet in an extended period of rain, you could use a thin plastic pack liner inside of the bag for extra protection.

The top portion of the bag has a 10″ daisy chain at the back and a sections of shock cord that criss crosses the top.  These allow you to attach other gear to the outside of the bag for quick storage.  I’m planning to use the daisy chain to hold a blinky light for any night riding occasions.

The bottom of the bag has a plastic reinforcement to help it keeps it’s shape.  This gives the bag it’s upward slope as it goes away from the seat post which gives you great tire clearance, even for full suspension bikes.

For my bag, I added a custom sleeve to the bottom of the bag to hold my tarp poles.  Joe is great to work with for custom features and he is willing to talk through options and come up with a plan for any custom touches you may need.

What Can It Carry?

It can hold a lot of gear such as an entire lightweight sleep system or a full set of bikepacking clothing including rain gear, spare clothes, and insulated jacket.  The great thing about the seat bags is then can range from 6L to 14L based on the contents you need to carry for a given trip.

seat bag with full sleep system packed

With my coroplast bags, I carried clothing, coffee making setup, tubes, rain gear, and other misc items in the seat bag.  After getting the J.Paks bag and testing various combinations of gear, I have switched to carrying my sleep system in the the seat bag.

The main reason for this change is because of how well the sleep system fits in to the bag and compresses down with the straps to hold everything in place.  With it fully loaded, the bag does not move around.  By putting my sleep system in the seat bag, I can pack it up in the morning and ride until it’s time to camp.

My standard items for the seat bag:

  • Cuben fiber tarp
  • Tyvek bivy
  • Synthetic midweight quilt
  • Tarp pole

These items do not completely fill the bag.  A down jacket, rain gear, or even an inflatable sleeping pad could still be added.

Attaching The Bag

Photo from the J.Paks website.

The bag attaches with two straps on the seat rails and a wide velcro seatpost mount.  The seat rail straps are designed to cross over the rails providing extra tension to prevent the bag from moving.

Once the bag is packed with gear, tightening the seat rail straps pulls the bag up against the saddle.  This helps stabilize the bag and keep it from swaying side to side.

As with any seat bag, it takes a bit of trial and error to find the right contents to fit the flared shape of the bag and get the bag to fit properly with your bike and saddle.  The trick seems to be having items at the front of the pack that can compress to allow the bag to really fit tight against the seat post and seat rails.

Riding With the SeatPak

When first looking at seat bags and how far they extend past the back of the seat, it’s easy to think they would bounce around and sway when riding singletrack.  I had the same thoughts, but that is not the case.  The combination of the velcro on the seat post and the crossing straps on the seat rails create a secure mount and you don’t even notice the bag when riding.

The Seat Pak is narrow at the seat post and flares out at the back of the bag.  Where the bag is under the saddle, it is never wider than the saddle and it never interferes with pedaling.  Even when fully packed, the bag has a slim profile.

Flare of the seat bag when fully packed

Overall Impressions

The SeatPak is awesome!  It was money well spent and there isn’t anything I would change about the bag.  Having a Colorado made bag that is made with sturdy yet lightweight materials is all you could ask for.

If you are in the market for a seat bag, give J.Paks a look.  He’s a one man operation like myself and he does excellent work.

About Andy Amick
A little bit nutty in general, a lotta bit nutty about bikes. Each of his boys received a bike helmet for their first birthday and the three of them have been biking together ever since.

Follow me on Twitter ·

Previous post:

Next post: