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Big Papa expedition seat pack

17 litre expedition bikepacking seat bag. Hardwearing, large capacity, exo-rail compatible with additional bungee cord for keeping your kit secure and safe

Big Papa Large capacity seat pack black
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  • Black - Big Papa Large capacity seat pack black
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Your bivvy bag, your hammock, the kitchen sink… There are no limits to what the beefy Big Papa can carry for you when you’re exploring the most rugged and remote corners of the world (within reason).

At an impressive 17 litres, Big Papa is our largest seat pack providing secure, spacious and hardwearing beneath-the-saddle storage.

Constructed from waterproof fabrics in our UK factory, Big Papa is made to meet the demands of adventure. It’s also available to your spec as a custom product.

Simple to fit and secure once mounted, Big Papa is at its most stable when attached to the Exo-Rail which reduces sway and increases stability. Attachment is quick, simple and secure with a slide-on, slide-off sleeve; 2 velcro seat post straps, and a stabilising saddle rail strap. If you don’t have an Exo-Rail, you can attach the Big Papa using just the saddle rail and seat post straps.

Roll-top closure and compression straps keep the load compact; external bungee cord is ideal for stashing your waterproofs and flip flops. 

"Is it waterproof?"

Although highly weather resistant, this product is not fully waterproof due to its stitched construction. If you are carrying valuables or electronic equipment, make sure to put it in a dry bag. 

Key features
  • 25 Year Alpine Bond
  • Hardwearing, high capacity storage for rugged world exploration
  • Made to last in the UK
  • Fully customisable (contact support@alpkit.com)
  • Made with waterproof and highly abrasion-resistant fabrics
  • Roll-top closure and compression straps for stability
  • Simple 3-point attachment system
  • Heavy-duty seat post straps with aluminium buckles
  • Bar-tacked saddle rail strap, angled for support
  • Reinforced contact points for durability
  • External bungee cord for stashing gear
  • Tapered cut doesn't interfere with your pedalling
  • Attaches beneath the saddle
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Vital stats

Stitched seams
Buckles: Duraflex S.J. buckle w/ Camlok; 20 mm aluminium


A 4-layer, 210 denier laminated nylon fabric with a DWR finish: VX21 (or X-Pac to its friends) is a high tech, ultralight sandwich of materials that is highly abrasion and tear resistant, low-stretch, and waterproof.
Weight: 380 g

Tarmac UltraLight

The lightest waterproof and abrasion resistant fabric we use, ideal for your ultralight long-distance racing or bikepacking set-up. A 70 denier Nylon Ripstop backer makes it super tough for its weight. 
We make LS07 products without a lining to keep them lightweight.
Weight: 340 g


Max capacity: 17 litres
Weight: 368 g
Size: 50 x 18 x 18 cm

Fitting guidelines

Minimum clearance from saddle rail to wheel:  22 cm
Minimum length from base of seat post to saddle: 16cm

Origin: United Kingdom

Product Care Information

​Big Papa has a C6 DWR coating which helps it to repel water and dirt. After your two-wheeled epic, wipe down your Big Papa with a damp cloth to remove dirt.

Product Support Team Advice

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What You Say: Customer Reviews and Comments

10 Reviews


Used this product?

Write a review

I took the Big Papa for a road cycling trip to Spain and I was very happy with it. When I learnt to pack properly (heavy stuff close to saddle) it had little sway and was unnoticeable on my road bike. I don't know how it would fare in technical mountain bike terrain, but awesome for road touring!

A well designed tail-pack...

Excellent tail-pack for overnight trips. Very stable even when packed with my tent sleeping bag and mat. A minor gripe is the length of the Velcro straps - on my bike I only get ~15 mm of overlap. Another 20 mm of strap length would make things more secure.

Big Papa

This product was recommended to me and I was not disappointed I used it for a weeks cycling doing the NC500 so neat and I couldn't feel it on the bike, no movement at all. The company delivered on time very prompt and efficient.

Great cost-effective product

I normally don’t write reviews but this product deserves one. I spent a lot time researching online and found that all available products were really expensive. Luckily I found this great company and this saddle bag. I needed a 17L bag and this was perfect. I bought it online and sent a couple of questions via email. The company was responsive to answer, the product arrived as expected and the quality of it is great. I just finished a four-day bike pack tour and I even felt the bag was attached to my saddle, it holds really tight, it offers an extra front strap to hold better, it is easy to mount/unmount and also easy to open to take things in and out. Very Happy with this purchase and it cost me 40% that the most publicized products. By the way during my tour, I use this bag together with the 13L Dry Bag for my handlebar.

Simple Great Product and Great Company!


This has been used on three bikepacking wild camps so far with various combos of kit packed into it.. This has included:
British army bivi bag, Exped synmat winterlite LW,lightweight down jacket,inflatable pillow.
DD hammock,and suspension straps/carabiners,Exped mat,above jacket and pillow.
DD jura2 sleeping bag by itself.
Make sure the available strap crossover under the saddle rails to prevent sway.All in all, a great seatpack.

Lone Red
BIG PAPA seat pack

First impressions- EXCELLENT!
Bombproof feel and construction to this product. Stitching quality is excellent with no loose raggy ends. Buckles top notch and the open aluminium style is a great time saving idea.
I look forward to stuffing my hammocking sleeping bag into it and updating my review next week.

Great quality and value

Having been hankering after some bike packing adventure for a while, a long weekend trip to Shetland on the road motivated me to buy a few bits from Appkit, after pretty thorough research into the various offerings on the market. Having only used the Big Papa once, I can't speak for its ability to weather the years but was very pleased with the product throughout and can't wait to take it out again on the chunky tyres. Very stable and straightforward enough to set up.

A few personal areas for improvement: the velcro straps for the seat post, as nice and secure as they are, I found the top one especially not to be quite long enough I think because of the angle of my saddle to seat post leaving a small gap between the seat post and bag; it still held but no harm in having the extra length. Setting the secondary saddle rail/ seat post strap for extra security is a bit taffy, particularly if you want to take the bag on and off regularly as I was doing each day. Lastly, again specific to if you need to take the bag off the bike and take it anywhere, a carry strap, nothing fancy, would be great - I used one of the many straps that the bag has anyway but none of them where comfortable over the 20 minute trek I made.

Regardless of the above points, the pros hugely outweigh the cons, and combined with great, friendly customer service from Alpkit and the price advantage over competitors, this and the companies equipment in general (I have a few other things) are surefire winners. Cheers.

Excellent bag with color matching my bike

The bag is solidly built with wide color range, I immediately bought one when I saw it available in yellow which perfectly matched my bike.
Most the straps are well built and offered plenty of adjustability except for the seat post straps which are way too short for my Trek bike. I have to cut some Velcro strips for extension. However, since I use the bike for daily commute between office and home, so the strap extensions should be no issue except for the look; for that only 4 stars.

Philip Malcolm
Sturdy, Roomy but flawed

I've been using the Big Papa since May for overnight bivvies, one long day on the road and an Ultra MTB event. In terms of capacity, it's excellent. I've had variously my sleeping system and enough food to kill man, 2 days clothes and my shower gear and all of the above in various combinations in there. It cinches up tight and fastens on securely.

There are downsides, however. The Velcro straps could be longer to remove the rub on clothing when riding and keep the bag more secure. When you tighten the buckle straps through the saddle down it has a tendency to pinch the pack in the middle, causing the back end to sag towards the wheel. Finally, the trailing strap on the aluminium buckle is far too long and finding somewhere to bundle it up out of the way is a pain. There was one occasion I was rudely deposited trailside after it bounced free on a rocky descent in the Ardennes and wrapped it's way between my brake disc and hub stopping the back wheel. On this occasion, however, the pack was not enormously full and maybe that contributed to the strap having so much spare.


Poorly designed velcro fixing caused a hole to be rubbed through my shorts on the first outing. Alpkit modified the bag but offered no goodwill gesture for my damaged kit, despite me heavily documenting the case. Big Papa still at prototype stage.


“Thank you for your review. We have passed your feedback directly to the Product Design team for consideration in future designs. In the meantime, I hope that the modification has made the Big Papa more suitable for your requirements. Please feel free to contact us at support@alpkit.com / 01773417007 if you need anything else.”