Carbon vs. Alloy – which is best for me?

Which is more durable Carbon or Alloy?

Durability is a very real consideration for all riders, especially if you are planning to go off road or going on a long trip. A commonly help opinion is that a carbon fibre product is not as durable as a metal equivalent and whilst in some instances this can be the case the reality is real-world durability is comparable between our Carbon parts and their Alloy equivalents. 

We predominately use Toray T700 carbon fibre (‘higher grade’ T800 and above carbon fibres are more brittle and not able to take a knock). Our priority is to have something strong, stiff and, importantly, tough. We also use a mix of UD (unidirectional) with 3K Twill/Weave in high-stress areas like the sidebar and top pivots. The 3K weave also creates the characteristic final finish.

When developing our arches, we conducted extensive testing to ensure they could be used on and off-road. Our protocols were as follows:

Static Test – We loaded-up 3x times the max weight on the arch (e.g 81kg). To pass the test the arch must not break.
Dynamic Test – To pass the arch must survive 100,000 cycles with recommended max weight (27kg) on our vibrating test rig.

Both Carbon and Alloy arches passed these tests without issue.

Your Riding Style

One final consideration is where you plan to ride. If you’re heading off-road, away from civilisation, then we’d recommend our Alloy options. Why? In worst case scenarios (dropping or crashing your bike) an Alloy Arch can withstand abuse a little better and can possibly be repaired or ridden when damaged – it will tend to bend. One other advantage of Alloy is the addition of triple-bosses and the extra capabilities these add. With triple bosses on the sides, it is possible to add extra cargo or bottle cages to the arch – essential if you don’t know when you’ll be replenishing your water and food supplies next. 

Does this mean that our arches are indestructible? No, unfortunately not. As with every component on your bike, there are limits. It’s a reason why we also offer a Crash Replacement policy if things do go wrong. 

Why would you choose Carbon over Alloy?

So if carbon fibre is more expensive, why would you choose it? A couple of reasons: aesthetics and weight. As mentioned above, the carbon arches are produced in moulds, and as such, it’s possible to create shapes that just aren’t possible with a metal equivalent. A great example of this ability to shape carbon is the modern-day time trial bike. Almost all, regardless of brand, are produced in carbon fibre – to create the same aerodynamic frames in metal would be wholly impractical (and very heavy!). In the same way we are able to create a more delicate looking carbon arch complete with complicated shaping that just looks right on a modern bike and lightyears ahead of the looks and weight of traditional bike racks that have come before.

Carbon fibre also has a higher strength-to-weight ratio than alloy. This is a key reason why the aerospace industry utilises carbon fibre composites throughout an aircraft, where parts must be strong yet lightweight. Carbon fibre offers exceptional strength to weight, meaning a lighter arch that is still capable of carrying the same load as our Alloy arches. If weight saving is a priority for you, then carbon fibre is the way to go. For example, our Carbon Arch without Pannier Mounts tips the scales at just 163g, compared to 370g for the Alloy equivalent. 

What materials does Tailfin use?

We use Toray T700 carbon fibre for our Carbon Arches and Top Stays and 6061-T6 Alloy for our Alloy Arches and Top Stays. All these items are produced by our manufacturing partner in Taiwan (a country renowned for its expertise in bike component manufacturing). However, the manufacturing processes are very different between these two materials.

How are our Alloy parts made?

In comparison, our Alloy arches are relatively straightforward to produce, with many stages of the process being automated, requiring far less manual input. Lengths of Alloy tubing are extruded and cut to size (imagine pushing modelling clay through a hole and then cutting it to size). From here, the tubing is bent into shape, and the relevant connector pieces are welded in place. Compared with our Carbon Arches, this is a far simpler component to produce, thus, is more economical in cost. 

How are our Carbon parts made?

Carbon fibre production is known, to most people, as a cutting-edge technology but in reality, creating carbon fibre parts is a surprisingly manual, almost artisan-like process. It requires a high level of knowledge and expertise to transform loose carbon fibres or woven sheets of carbon fibres into a bicycle rack capable of circumnavigating the US or competing in an ultra-endurance race such as the Silk Road Mountain Race. 

Many complex steps are involved in producing a carbon arch or topstay. Breaking the process down simply, sheets of resin-coated carbon fibre are placed in a mould and baked in an autoclave. The autoclave acts like an oven and cures the resin, after which the arch is removed and ready for the final finishing touches. 

In reality, the placement and orientation of the fibres (and sheets) will change depending on which part of the arch or topstay is being created. This allows the part to be strong and stiff where it needs to be and minimises the amount of material required, cutting unwanted weight. Multiple layers are built up by hand, and it takes skill to lay the sheets perfectly, avoiding any unnecessary overlaps or weak spots. Our arches also require additional parts to be bonded and incorporated into this process, adding to the complexity.

Thanks to this complex, labour-intensive process, the cost of producing our carbon fibre parts is significantly higher than that of Alloy parts.

Modularity

Lastly, it’s worth emphasising that your decision between Carbon or Alloy needn’t be final. A unique feature of Tailfin products is modularity. Components have been designed to be replaceable and can be swapped over. So if you purchase an Alloy AeroPack and panniers for your off-road trips and then want to save weight for an upcoming ultra-distance road race, it’s possible to purchase a Carbon Arch on its own and swap these over in a matter of minutes, ready for the start line. We sell all individual parts on our website.

Find out more about the Tailfin product range in the comprehensive Product Guide.