So it’s time to buy a new bike, and the choices have never been greater – or so very complicated! But one of the choices at least should be a little simpler than the others – should you buy a bike made of traditional aluminum or try a carbon fiber bike frame? We’ll see if we can help you to answer that question by providing some key information on carbon fiber. Bear in mind that this article is written with road bikes in mind – not mountain bikes (maybe we’ll cover them in another article later).
Carbon fiber is incredibly stiff, but the incredible stiffness properties comes at a price – by itself, it is innately brittle and prone to splitting and cracking. To make it suitable for building bike frames, it’s suspended in a glue-like material called epoxy resin and only then is it molded into frames. This composite material is displays some degree of plasticity, deforming under impact to help absorb sharp blows like a crash or a rock strike without splitting or cracking the fiber. And of course, it’s light, although these days a carbon fiber frame isn’t always lighter than an aluminum ultra-light.
Brief History of Carbon Fiber Frames
Believe it or not, carbon fiber frames hail back to the mid 1970’s when they were introduced as ultra-light specialties – at ultra-high prices! A custom-made carbon frame will still cost you some $2,000 to $5,000 but a standard off-the-shelf frame will come in at around half that – but is it worth it? Here are some basic comparisons with between aluminum and carbon frames:
Aluminum vs Carbon Frames
Because aluminum is denser than carbon fiber, it is commonly believed that carbon frames are the lighter of the two. Although this is true, it’s still possible to buy quality aluminum bikes that are lighter than some carbon bikes! Nevertheless, the more expensive carbon frames are generally lighter than their aluminum equivalent, but the difference in weight makes the price difference significant and the carbon option questionable for most of us.
2. Ride Comfort
Aluminium is denser than carbon and less elastic, so the frame tends to transmit more vibration into the rider. Carbon frames are better at absorbing vibration into their structure, especially the better designed ones, and so they do give a more comfortable, smoother ride. Even so, most honest riders will tell you that even over rough roads, the difference may be noticable but it is not really that large.
3. Strength and resistance to impact
There is much conflicting information on the repairability of carbon bikes! I have seen significant evidence that carbon bikes can be repaired – the bad press is no longer valid. In general, the process for repairing carbon frames is:-
a) inspect for damage
b) sand or cut away the damaged area
c) lay down new layers
d) sand the area again to match the shape of the original frame
e) apply clear-coat or paint
Testing has shown that repaired tubes are at least as strong as they were originally, and are often even stronger. But before you finally decide to buy a carbon frame check whether there is a repair facility in your town that can repair it in the event of damage.
As a general rule aluminum bikes are cheaper. Over recent years the prices of off-the-shelf carbon bikes have dropped and narrowed the difference, but you will almost always pay less for a good aluminum bike than for its carbon equivalent.
Do carbon bikes last? This is difficult to determine because it depends on the way you ride your bike and the type of damage that you may risk exposing it to. In general though, carbon frame are more durable to both forceful impacts and torque and a carbon frame could theoretically last you a lifetime if it’s well maintained. This wasn’t always true though – and thus, it’s very rare to see a carbon bike from the seventies still being ridden.
If you really are keen on marginal improvement in ride comfort, then a carbon frame is for you; but don’t then buy the cheapest carbon frame bike you can find – as always, check out the full bike specification. If like me, you are a leisure rider and your beer consumption will have a more significant effect on your performance than a slightly lighter bike will, then stick to aluminium and invest your extra dollars where they’ll make a real difference – a Brook’s saddle maybe and a top-end Shimano drive train!
I hope this basic information is useful for you – what are your thoughts? We’d love to hear from you.