Cage Packs and Cargo Straps – Product Design Notes

“A system is a group of interacting or interrelated elements that act according to a set of rules to form a unified whole.”

Rhubarb and custard, salt and pepper, cheese and pickle, Tom and Jerry, Laurel and Hardy; are there any more iconic pairings in life?

We have our iconic pairings in the bikepacking world, and right at the top of the list are cargo cages and dry bags. It’s common knowledge that this pairing is one of the most straightforward and low-tech methods for getting more kit on your bike. As long as you have the mounting points, granted. It’s a technique that, whilst being pretty excellent at delivering increased volume without needing a tonne of technical equipment, unfortunately also brings plenty of drawbacks. 

For cargo cage and dry bag users, achieving a solid, secure and consistent attachment has always been the challenge in making the system work. In theory, this should be pretty easy – simply wrap in straps and tighten – but as most of us know through experience, it can be anything but in practice. On top of this, making the process of attachment easily repeatable and not needing six hands to hold things in place are desirable attributes that existing offerings fail to live up to, in our opinion.

Tailfin Cage Pack System
Cargo cages and packs – the lightweight bikepacking choice.

We’ve already worked our magic with the Tailfin Cargo Cage range. Whereas many brands have created cargo cages as stand-alone products, we knew that the cage is only one part of a system. So we knew we had to address the issues users of cages and dry bags have experienced:

  • Time-consuming nature of threading straps through daisy chain style bag attachments
  • The need to have multiple hands to hold the bag in place and tighten straps
  • Poor alignment between cage and bag
  • Limited ability to adjust the height of the bag in relation to the cage
  • Standard dry bag dimensions are only really suited for use on forks

Just as with all of our products, the overarching objective was to provide a solution to answer all the problems we highlighted above.

Creating the Cage Pack System

Dry bags are so simple; how can we make them better? 

We first had to look at how we intended the Cage Pack system to be used. Rather than designing it just for positioning on the outside of the fork leg as most current products seem to be, we realised that our Cage Pack could be used in other positions around the bike through careful shaping. So wherever you can fit a cargo cage, you should be able to use a Cage Pack.

Shaped to fit in all locations.

Luckily this is where our expertise in using laminated materials combined with our construction techniques enabled us to get away from the typical, basic cylindrical shape employed by many drybags. Instead, we can create more complex forms that are perfect for use in areas where clearances are essential, such as within the frame or under the down tube. If you’ve ever felt the annoyance of rubbing your leg on an ill-fitting frame bag or noticed your bottle or bag being worn through by the chainring when fitted under the downtube, this aspect of our design will resonate.

To optimise the shape and sizing of the Cage Packs, we started with a set number of prerequisites. The smallest 1.7-litre pack must be able to carry items equivalent in volume and dimensions to a standard 74mm diameter water bottle. The 1.7 litre must also have a maximum width that will allow it to fit within the standard q-factor/bottom bracket width of a road or gravel bike*. Equally, the 3-litre version must fit within the standard q-factor/bottom bracket width of a mountain bike*. These parameters also ensure that carrying the 1.7-litre version within the frame provides minimal leg rub.

*average, not every road/gravel/MTB

Crank clearance was an important factor.

The result of this design brief and subsequent prototyping and testing led to the shape you see before you. Rather than cylindrical, each Cage Packs has a flat-sided profile intended to reduce interference with cranks or rider. There is also a second benefit of creating the Cage Packs in this unique shape; additional volume.

Introducing the Speed Hook concept

The pièce de résistance of the Cage Pack system has to be the in-built Speed Hooks. These small but perfectly formed thermoplastic hooks might look inconspicuous but elevate the Cage Pack to more than just a well-appointed drybag. 

The Speed Hooks are a genuine innovation

The Speed Hook is our answer to addressing the top three issues research led us to identify as the problems to rectify when it comes to failings in the cargo cage/drybag system.

  1. Time-consuming nature of threading straps through daisy chain style bag attachments

We created the Speed Hooks with an open lower end allowing for rapid engagement and release from straps, unlike a closed daisy chain. In addition, the flexible nature of the thermoplastic material makes it easy to guide over the straps. An additional lip at the lower part of the hook prevents unwanted release, which is essential for added security when riding on uneven trails.  

  1. The need to have multiple hands to hold the bag in place and tighten straps

The open nature of the Speed Hook enables you to semi-set your straps and lower the Cage Pack into it. Once the Speed Hooks are engaged, you can let go, and the bag will remain in place, enabling you to tighten the straps fully with both hands.

Tailfin Cage Pack System
Only two hands needed.
  1. Poor alignment between cage and bag

As the Cage Packs are for use in conjunction with our Cargo Cages, we could place the Speed Hooks at the same spacing as the strap slots found on both sizes of Tailfin Cargo Cage. Couple this with the soft back panel, and the Cage Pack aligns snugly and securely with a cage. 

On top of this purposeful partnership, the alignment of the Speed Hooks is also very compatible when used with other brand cages and straps. Not just for exclusive use with Tailfin Cargo Cages. 

Tailfin Cage Pack System
Perfect alignment between cage, strap and pack.

Construction of the Cage Pack System

Whilst it may be devoid of the characteristic Tailfin internal structure, the Cage Pack system retains the typical Tailfin innovation you would typically expect. We continue to use the combination of heavy-duty 420D Hypalon laminate in high wear areas and lighter, more flexible ripstop nylon in all other areas to create a very conformable shape. Roll-top closure provides easy, weatherproof access. As with all Tailfin technical bikepacking bags, we construct the Cage Pack using a process of welding the fabrics together to create a completely watertight, seam-free package. This construction method guarantees the Cage Packs are 100% waterproof – a feature that provides great peace of mind when carrying your essential camping and safety kit.

The typical Tailfin 100% waterproof guarantee.

What about the straps?

We have to confess that the first paragraph of this article is technically misleading. The cargo pack system is, in fact, a trifecta of parts rather than a duo. So we could have started with ‘three, it’s the magic number’… (sorry).

We often take using a cargo strap to attach a bag to a cage for granted, but the strap’s performance plays a crucial part in the system. For a component that at first glance seems incredibly basic, it’s mind-blowing just how much thought goes into creating one that works well.

Take our new TPU Cargo Strap. It might look very similar to almost every other cargo strap on the market; a design brought to popularity by the ski strap brand Voile. Still, it has a myriad of subtle differences. For instance, we went through over sixty different physical prototypes of the buckle shape to nail down a form that works perfectly with soft bags!

Rigorous testing of materials led to the specifically tuned TPU (Thermoplastic Polyurethane) material we have used for our straps. The compound balances stretch, grip and strength whilst operating consistently over a wide temperature range. Choosing the perfect TPU has been one of the main reasons it took us so long to release our cargo straps. Just as with tyre rubber compounds, there are simply an almost mind-blowing number of different TPU compounds, with many being very similar. Merely sampling, testing, and narrowing the selection to a number that could be produced in prototype form was incredibly time-consuming.

The final TPU compound we chose is a heavily guarded secret but suffice to say that it also proves highly abrasion-resistant through our real-world and lab testing. Abrasion resistance is fundamental since the critical locations for application are also prime areas for collecting mud, grit and other trail debris. This need for strength also led us to use Nylon 6/6 for the Load Lock Buckle – a material that proves almost indestructible. We had great fun smashing prototypes with rocks and hammers, and amazingly it bounces back to shape without breaking a sweat. 

Tailfin Cage Pack System
Abrasion resistance is key.

The most crucial performance feature we needed to ensure with the new strap was providing an effective and positive engagement and making it easy to use even with gloves.

To this end, we refined the shape of the buckle hook (or prong to give it its correct technical name) to have three-dimensional shaping and developed specifically shaped strap eyelets to work best with soft bags and compressible loads.

Buckle refinement was one of the hardest and most time-consuming parts.

The design incorporates a self-locking mechanism that holds fast even when your bag contents shift, an engineered feature that creates peace of mind even when riding rough terrain. Another distinct feature is the eyelets cover almost the whole length of the strap to maximise usable length.

We also kept the standard 20mm width to ensure a universal fit with all cargo cages and bags. Three lengths are also available (to start with): 40, 50 and 65cm for compatibility with all sizes of bags and cargo. Each strap also comes with a soft compound Strap Keeper to provide clean and straightforward strap management.

Just as with all our finished products we are aiming for the full Cargo System to provide the solution to another aspect of bikepacking life. Effectively we want the Cargo Cages, Cage Packs and Cargo Straps to be the last cage based bikepacking storage system you ever need to buy.

You can view the complete Tailfin Cargo System below.

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