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Aluminium vs Carbon - Which Is The Best Material For My Next Bike Frame?

01 May 2020

Blogs

When it comes to choosing a new bike, there are several options when it comes to the frame material - steel, titanium, aluminium, carbon fibre - you can find very good bikes made out of any of these materials and each comes with it’s own specific qualities and advantages.

However, more often than not, if you’re looking for either a standard road or off-road bike, you’ll only need to decide between two - carbon fibre or aluminium. There isn’t really one ‘best’ material – but there is certainly a best for you, based upon your riding plans, requirement and budget.

Let’s take a look at how each of these materials fair in key categories that are important to consider when it comes to cycling.

Strength

Carbon fibre and aluminium are both very strong materials, otherwise it wouldn’t be possible to build bikes out of them! Carbon fibre sometimes has the reputation of not being particularly strong, however in reality, its strength to weight ratio is actually higher than steel. The way Giant lays up the carbon in its factories ensures that strength is never compromised to save in other areas such as weight. However, it isn’t suited to every cycling discipline which is why aluminium still has its place.

Aluminium can be a little more ‘forgiving’. It is often popular for cycling disciplines like crit racing, downhill and freeride mountain biking where there is a high likelihood of taking a tumble due the nature of the racing. It's possible for these types of frames to be put through certain impacts but still be strong enough to continue using. However, we would stress that any impact to a carbon or aluminium frame should be inspected by an experienced mechanic before being ridden again. 

Here at Giant, we offer a Lifetime Frame Warranty on all our bikes, so whatever bike you’re riding, you can ride in total confidence.

Winner: This is hard to say, as it really depends on the type of riding you plan on doing. For extreme off-road, aluminium. For road riding, carbon fibre.

Aluminium is a popular choice for cycling disciplines like downhill and freeride mountain biking

Stiffness

An essential property for any good bike frame material is for it to be stiff. A stiff material will ensure all the power you’re putting into the pedals will transfer to the back wheel and propel you forward. A frame that isn’t stiff will flex and some of your power will be lost within the frame. 

How stiff a frame is comes down to how it is manufactured. Manufacturers can make an aluminium frame stiffer by adding material in specific places or using specific tube shapes, but due to the properties of aluminium (as a metal) this can be a difficult process and there is a limit to what can be done. When it comes to carbon fibre however, it has the advantage of being far easier to ‘tune’. By changing the carbon layup or just the direction the carbon strands are laid, specific ride characteristics can be achieved. It can be made stiff in one specific direction or just in one specific spot.

Winner: Carbon

With carbon fibre, manufacturers can lay it up in specific ways to strengthen the frame in certain areas, for example around the bottom bracket 

Compliance

Compliance, or comfort, is linked closely with stiffness. Whilst you want a stiff bike, you don't want it to be so stiff that it gives a jarring or uncomfortable ride, so it’s important to get a good balance of stiffness and compliance when manufacturing bike frames, no matter which material.

Due to the nature of aluminium and the fact it has to be welded and butted at joints, many people find aluminium less compliant than carbon but for certain riders aluminium is still best. For example, aluminium is often used as a winter bike for road riders and is the go to choice for commuters. However, as we’ve said above, because carbon fibre frames can be layered in very specific ways, engineers are able to tune the frame to be stiff and comfortable. By layering fibres of carbon in a specific pattern, the frame can be laterally stiff and vertically compliant which is ideal for a bicycle. Furthermore, carbon tends to dampen vibration better than aluminium, simply because of its material properties adding to the comfort aspect.

It is worth noting however that frame material is only one, small part of overall comfort on a bike. Two factors that really influence how comfortable your bike feels are your tyres and touchpoints. If your bike feels harsh, running wider tyres at lower pressure should make a noticable difference. Equally, swapping for more compliant handlebars and seatposts (such as the D-Fuse range) or even just fitting thicker bar tape can make a significant improvement.

Winner: Carbon

For many, carbon fibre offers a more forgiving ride. Although aluminium is still favoured by some riders because of the 'real' feel it can offer 

Weight

For many riders, the weight of the bike is the primary concern. Having a lightweight bike makes climbing easier and can make the bike easier to manoeuvre. Whilst it’s possible to make a light bike out of either material, when it comes to weight, carbon definitely has the advantage. A carbon fibre frame will almost always be lighter than an aluminium equivalent and you’ll only find carbon fibre bikes in the pro peloton,in part because of the weight benefits. 

It’s worth noting that not all carbon fibre is equal and it’s possible that a low grade carbon frame could weigh more than a high-end aluminum frame. Also of note is that components can add significant weight to a bike, so an aluminium bike with carbon wheels could be lighter than a carbon bike with aluminium wheels.

Winner: Carbon

Carbon fibre has the reputation of being super lightweight, but it's possible to get lightweight bikes in both carbon fibre and aluminium 

Price

We’d love to say that you should only consider the above points when choosing your bike, but for everyone, price is likely to play a pivotal role in the decision you make. 

When it comes to manufacturing, carbon is more expensive. This is down to a greater level of engineering required, the manufacturing process being more labour-intensive (many carbon frames are laid up by hand) and the fact that each carbon frame requires specific moulds that further increase the cost.

With that being said, you can find bikes made from both materials at a huge range of price points and a cheap carbon frame may not be as good a quality as an equivalent priced aluminium frame. As a consumer it’s frame material is almost just as important as the component spec when it comes to price.

Winner: Aluminium 

Aluminium is often cheaper than carbon, but not always 

Summary

Based on the above points, it’s clear that carbon takes the win. But we can’t stress enough that it really does depend on you, the riding you plan on doing and what you want from a bike. A carbon fibre bike really isn’t for everyone and there are a huge range of fantastic aluminium bikes out there, such as the Contend AR range or Talon range.

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