Which material should you choose for your mountain bike frame? Carbon vs aluminium - Dirt

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Which material should you choose for your mountain bike frame? Carbon vs aluminium

Plastic vs metal

There are two main frame materials you will encounter when deciding to buy a mountain bike – carbon and aluminium.  Most of the bikes ridden at World Cup/Enduro World Series level will be carbon (although it isn’t ubiquitous) but it would be simplistic, and maybe even wrong, to say that carbon is objectively better. Let’s take a look at the advantages and disadvantages of each material.

Aluminium

When we say aluminium we don’t mean pure aluminium but a mixture of 95-98 per cent aluminium with a few other metals thrown in – this is why you may see it referred to as alloy. The most common alloy used in mountain biking is 6061 as it is highly weldable – although each company has its own ‘unique’ name for it. Orange Bikes are an example of a brand with a long history in aluminium, with their full-suspension frames such as the Five, Alpine and 324 still being manufactured here in the UK.

Carbon

It used to be that carbon fibre bikes were exotic, high cost items with a reputation for snapping, but things have changed. Carbon technology has been refined so that durability is less of a factor and the price is also rapidly falling (although on average you will still probably have to pay more for carbon).

Carbon can be moulded into more interesting shapes than aluminium so if you see a frame with an exotic silhouette it’s likely to be carbon, not aluminium. It’s also hard to strictly define the properties of carbon because the way the carbon fibres are woven give different characteristics.

One thing you should avoid is counterfeit carbon components that are not made to industry standards. Always buy from a legitimate source and if you find yourself looking at a bit of carbon kit on the internet that seems too cheap to be true it may be worth leaving it, we’ve heard too many horror stories of poorly built fakes causing real harm.

Which is better?

As we’ve already said, there’s really no hard and fast rule for this, but each material has a set of distinct properties that suit different riding styles

Cost

On average, an aluminium bike will be cheaper than a carbon bike. This has always been true but the gap between the two is definitely narrowing.

This isn’t even a hard and fast rule anymore as there are times when a well specced aluminium bike will cost more than a moderately specced carbon bike. This has been accelerated by the introduction of direct sales brands like YT Industries and Canyon who both offer carbon downhill bikes for under £3,000.

Weight

Carbon is lighter. For climbing and on the flat this will obviously always be an advantage as you have less friction and gravitational force to overcome. However, there are certain schools of thought that would suggest for descending a bit of extra mass can actually help. Jacy Shumilak, Sam Hill’s mechanic, for example, reckons that 38.5lbs (17.4 kg) is the sweet spot for a downhill bike, and that any less weight is detrimental to performance.

Stiffness

Again carbon takes the honours with this but worshipping at the church of stiffness could leave you battered and bruised. A carbon bike will be snappier and respond briskly to input from the pedals or the bars, but when you’re up to speed it will be less able to soak up the trail chatter and could bounce around off big hits.

It’s worth saying that these are big generalisations – feel itself is very subjective and different frame shapes and weaves react very differently to different trail conditions. We tested the carbon and aluminium versions of the Devinci Wilson though and found them to have an element of truth.

Durability

Here’s the thing, mountain bikes break. They are put through immense stresses in their lives and inevitably some will fail. There are some brands that are more notorious for this than others but it doesn’t really come down to carbon vs aluminium.  An observation that may or may not reassure you is that we’ve seen an awful lot more broken riders than bikes in our time.

The key thing to understand is that aluminium will deform whereas carbon will crack. A dented aluminium frame can still be ridden (as much as a manufacturer wouldn’t recommend it) whereas a snapped carbon frame is a write off – which may be something to consider.

Whatever you go for you should definitely check the warranty and crash replacement policy. When you’re spending this much money on a frame that could well break you want to make sure you’re covered.

"We manufacture, finish and assemble in the UK so we’re better placed to deal with the short term effects of the current market conditions. However, mid to long term instability wouldn’t be good for any business and we are no exception." Jay Tolan, General Manager Orange Bikes.

So what about steel?

The majority of ‘mountain bikes’ (or at least mountain bike shaped objects) are actually made from steel, and historically it was the material of choice but there aren’t many you’d want to take down your local trails. Nowadays 99 per cent of the bikes we’re interested in will be carbon or aluminium, but there are some manufacturers who have stayed true to steel.

“But why?” You might ask. Well steel not only has a retro charm with its straight, circular tubes, but it has inherent damping properties not found in aluminium or carbon. Steel hardtail riders claim it dulls some of the trail chatter that’s transmitted through the frame and gives a smoother ride as a result. Steel is also incredibly durable and a well made steel bike will probably outlast an aluminium or carbon equivalent. It is repairable too, adding to its longevity.

Unfortunately steel is heavy (it actually has a density roughly three times that of aluminium) which means you’re likely to be lugging round a bit of extra mass in return for the natural absorption – not a compromise most riders are willing to make.

If steel sounds like it could be the material for you check out Cotic’s new range of Drop Link full suspension models or hardcore hardtails such as the Chromag Stylus, Ragley Bluepig, Cotic Bfe  and On One 456.

Titanium

In an ideal world we would probably make a lot more bikes out of the ‘magic metal’ that is titanium. It’s light, strong and provides a lovely ride but there’s just one problem – it’s bloody expensive. It’s also very difficult to work with and a contaminated weld can spell death for a frame making it a risk for manufacturers to work with.

As such it’s a niche material for those looking for something ‘a bit different’. Take a look at Lynskey or Stanton’s Switchback for some very special titanium bikes, just be sure to keep your credit card in another room.

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