I am going to buy my first proper road bike, and I have been comparing entry-level carbon frames with top-level aluminum frames in the same series (Giant Defy). What are the benefits of carbon vs. aluminum frames? Is it better to get an aluminum bike with higher-end components or a similarly priced carbon bike with lower-end components?

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    What's wrong with a plain old steel frame? Apr 21, 2013 at 11:53
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    the defy doesn't come in steel Apr 21, 2013 at 12:02
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    You may want to make your question less specific to the Giant Defy and more about the entry-level carbon vs. aluminum frame. Questions benefit from being relevant from year to year and across manufacturers.
    – WTHarper
    Apr 21, 2013 at 13:43
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    I purchased a Defy3 last August when I returned to biking after a 35 year hiatus. I can't provide much insight regarding aluminum frames vs. composite, but I can tell you that I am very pleased with my choice. To date I have ridden the bike for almost 1500 miles with only a broken spoke spoiling an otherwise flawless experience. I must admit that I often lust for more exotic bikes and components, but my old engineer's head tells me that the best upgrade will come from improvement of the guy in the saddle; I'm making progress.
    – user6691
    Apr 21, 2013 at 23:55
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    @AndrewWelch I took a stab at focusing the question a bit more on the cost trade-off issues. If this isn't what you're going for, please feel free to revert.
    – amcnabb
    Apr 22, 2013 at 16:11

12 Answers 12


Essentially this is about low end carbon versus high end alloy. Carbon is typically lighter and less harsh (more vibration absorption) than alloy, but is not as robust. I doubt that the alloy is much heavier. I think it will come down to the difference in component quality and your budget.

Personally for a training bike I would probably go for the alloy, but that is driven by my financial situation. If the bikes are of similar price and the components are of the same quality, I would consider the carbon. However I would not trade component quality for a carbon frame.

Edit : Seven years after the answer was give. Many of the techniques learn laying up carbon, and with advances in hydroforming alloy, have lead to allow alloy frames that are significantly cheaper to fabricate yet nearly as light (if not lighter) than low end carbon frames, while having the characteristics of stiffness and compliance where wanted. You can no longer discuss 'Carbon' and 'Non-Carbon' frames as most major manufacturers have 2, 3 or more variations of carbon from 'cheap and cheerful' to 'insanely light and expensive'. The cost saving in Alloy frames put into better components leads to a better bike for the same build cost. As carbon is considered more desirable by many, it fetches a higher price for the bike.

TL;DR when buying a bike, look at the whole bike, not just the frame.

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    The component quality he'll be trading is not the highest anyway as I doubt the components include much carbon bits, if any ;) It's easier to get carbon frame then upgrade to components with lots of carbon material than to start with alloy frame and components and upgrade them later with carbon ones.
    – imel96
    Apr 30, 2013 at 3:07
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    As stated in another comment - I do not believe in buying a bike with the intention of upgrading - its a waste of money as parts are insanely expensive. Buy the bike to want, not a bike you want to upgrade.
    – mattnz
    Apr 30, 2013 at 9:16
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    I saw that comment and I think it's the main point. Comparing low end carbon with high end alu means he wants carbon but budget is limited. So, your suggestion is not really to buy the bike he wants but a bike that he's willing to settle with. Buying to upgrade is admitting that it's not the dream bike but at least you get some of the things that you really want and know that you can make it better. It's like comparing 50:50 and 80:20, they both total to 100. I'd rather be satisfied with 80% and accept the rest 20% sucks, than have 50% satisfaction for the whole package.
    – imel96
    May 1, 2013 at 2:15
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    -1, carbon is not 'not as robust' as aluminum.
    – 7thGalaxy
    Jun 23, 2014 at 7:38
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    @7thGalaxy The answer is correct, despite being stronger and stiffer than alu alloy, carbon is much less resilient to bumps and knocks. Givin a hard enough impact carbon will fracture whilst aluminium will just bend or dent.
    – harryg
    Jun 23, 2014 at 8:35

You are making the classical mistake of thinking that you can get the "perfect" bike on the first go round. Without the experience of where and when you'll ride, it is 100% likely that your first bike will be the wrong bike in some way.

I'd say take your current budget, cut it in half and buy a bike that fits you well, regardless of what it's made of. Used would definitely be best if you can judge whether a bike is used or abused ( or have a friend that can). Most of the time used bikes are lightly used and are a great deal. Having the design of the frame match the style of riding you do is far more important than what it's made of and you can't really make that judgement until you've got some miles under your belt.

Ride that bike for 4 or 5 months and then you'll know a lot more about what compromises to make in your next bike. And in another season or two after that if you're still riding, you'll might get it exactly right on your 3rd bike.

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    +1 this answer is worthwhile although it doesn't directly address the question. Find a frame geometry that suits your style and components you like. When you hone these choices down over a few different bikes, you'll know right away if the hot new carbon build you've been eyeballing is really what you want/need.
    – ebrohman
    Aug 4, 2015 at 21:01
  • this answer turned out to be pretty spot on. Got a carbon bike but couldn't get on with the size. so yeah. now this is basically my plan. Nov 16, 2020 at 13:07

If I were you I would satisfy myself as to the quality of the carbon frame of the bike you're considering, and provided it looks decent, to go down the carbon route.

The reason for this is just upgradeability. It is conceivable that as you become better and stronger on your first road bike, sooner or later you may find yourself asking the question "how can I make my bike faster?".

Now, for most of us the answer to this is to lose 10% in weight and 10% in body fat, but that's a different story ;-)

But when you start to think about upgrading parts, you've got your groupset, wheels etc. These things you can generally upgrade at your own pace, and as your budget allows. And they would apply to any bike, carbon or not.

I think if you have a non-carbon-framed bike, however, one of the big things to think about as regards an upgrade is the frame itself, i.e. basically buying yourself a new bike. And, of course, this will be pretty expensive and not really something you can do piecemeal.

In summary I would probably go for as good a frame as I could afford, and initially sacrifice things like groupset, just on the grounds that I can upgrade this kind of thing later as and when funds allow.

Incidentally I have a Giant TCR Advanced and think it is superb. I have no experience of the Defy but if the workmanship is like the TCR I doubt you'd be disappointed.

One last thing, since you say you're based in London and especially if cost is an issue....you could do a lot worse than looking at the Chris Boardman range out of Halfords. Just look at the awards these bikes win, you really do get a lot of bang for your buck.

  • Just as a small addendum, reading about the Defy, I think the fact that Sep Vanmarke had a podium finish in this year's Paris-Roubaix (on a Defy) would allay any fears I had about build quality! The bike's not going to be crap. http://www.giant-bicycles.com/en-gb/news/article/vanmarcke.podiums.at.paris.roubaix/16595/
    – PeteH
    Apr 22, 2013 at 18:32
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    I would never buy with the intention of upgrading - individual parts cost about 1000 times what the cost of the same part on the bike - to the extend is it cheaper to buy a donor bike than replace worn out parts on an otherwise good frame. Better defer purchase and save up the small difference than to buy a less than ideal bike and save up enough money for the substantial cost to upgrade it.
    – mattnz
    Apr 23, 2013 at 3:05
  • @mattnz - point taken, and without doubt parts cost less with a new bike, but it really depends on what you can afford right now and how long you're prepared to remain bikeless while you're saving
    – PeteH
    Apr 23, 2013 at 7:11
  • Disagree strongly with mattnz. I assembled my last bike from individual components and it would have been the same cost as buying it pre-built. In actuality I saved $1000 because I was able to score lightly used wheels and frame. There's always the upgrade cost of now having an "extra" part to get rid of, but that's part of the process. Aug 27, 2013 at 19:46
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    I'm with @BrianKnoblauch on this. There are PLENTY of not-new parts which can be had for modest prices. Granted you should know how to do some wrenching to maximize the savings.
    – jqning
    Aug 4, 2015 at 17:23

One thing that I have found is you can usually get a lighter weight bike if you go with top-level aluminum over a low-level carbon. The low-level carbon frames tend to have a lot of fiberglass mixed in to keep the cost down and the components are much cheaper too which will weigh a lot more. I think it's kind of funny that everyone looks down on my aluminum bike and yet it weighs less than their carbon bikes that cost twice as much! I have owned carbon, steel and aluminum bikes

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    I have guys look down at my Steel Hard-tail MTB, till they can't catch me......
    – mattnz
    Apr 28, 2013 at 9:43

From http://www.livestrong.com/article/86919-aluminum-vs.-carbon-bikes/ (I can't testify to the accuracy of this)

Aluminum frames possess the shortest fatigue life of any material used to manufacture bicycle frames. The typical aluminum frame possesses a life expectancy of five to 10 years. Conversely, carbon possesses the longest fatigue life. Most manufacturers provide a lifetime warranty on carbon frames. Some manufacturers offer a lifetime warranty on their aluminum frames, but most offer five to 10 years.

  • Which is why we called them Crackendale back in the day. That, and because the vibration cracks vertebrae.
    – jqning
    Aug 4, 2015 at 17:24

Personally id rather have top quality aluminium than cheap entry level carbon.

Whatever you choose, don't go daft with the upgrades-save your money and get a really nice carbon number in a year or two.

Entry level bikes are great when starting out. You can strip them, fit new parts by yourself, which obviously is a great thing to learn, but if you dive right in and buy an expensive bike you would be very hesitant to start working on it yourself.

Also, if you join a club and keep getting dropped then its only to be expected. Turn up with an s-works with di2 dura ace however, then not only would you feel a bit of a plonker getting beat by old guys on old raleighs, but I'm sure they'd also take great pleasure from it!

Whatever you choose/chose, good luck and happy cycling!

  • Much of this answer compares entry level bikes with expensive bikes--I'm not sure this really answers whether it's better to get a similarly priced aluminum or carbon bike.
    – amcnabb
    Aug 12, 2013 at 17:50
  • And if old guys are beating you as a younger rider, let them have their moment, they've earned it. You'll be faster than them soon anyway if you stick with it
    – Swifty
    May 10, 2020 at 8:40

I was faced with a similar situation about two years ago. I decided to go 2nd hand aluminum. The reason was that I didn't want to spend too much before I really knew what I wanted. There are several different types of road bicycle set-ups. This is what I didn't know: Will I want to ride long distances (100+ miles) or sprint races (30-40 miles) or just regular rides with friends (a couple of hours here and there). Each of these bikes would have a different set-up, material and geometry. Will I ride a lot of hills? Would a compact crank or regular crank be better to my riding style? Buy a used, but decent condition al bike. After 2000km, you'll have a good idea of what type of bicycle you want to spend real money on, and you'll be able to sell the current one for very little loss. If you don't sell it, then you have a winter trainer for use inside. And in the all too familiar case that you buy the bike and rarely use it, you didn't spend 1500 to 2000 on something that just takes up room in your garage.

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    This is right on. In fact, what you want to do is buy the $1500 to $2000 bike that is taking up room in the garage from the person who made the wrong choice.
    – jqning
    Aug 4, 2015 at 17:25
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    I'd gladly help you riding your $2000 bike if you have it dusting in your garage. Jan 5, 2018 at 13:55

I've been looking at the exact same bikes because I think I want to ride longer rides than just commuting to work. I've test ridden the 2014 Defy Advanced carbon 1 with Ultegra, 2013 Defy carbon 2 with SRAM Apex, and 2014 Defy 1 aluminum with 105.

I did not ride enough to tell if the Advanced carbon is that much better than the regular carbon but both are much nicer and smoother to ride than the aluminum. I think this will be good for longer rides. The carbon frames were definitely lighter than the aluminum but the aluminum was still very light.

The mechanical Ultegra group set was very precise but so was the 105 group set. I didn't like the Apex set mostly for the shift levers. The Shimano sets had much lighter shifting and shifts felt very solid. Adjustments may make the Apex just as good.

For my budget I can afford the Defy 1 aluminum but will wait till I can afford the 2014 Defy carbon 2 with 105. Shimano has a new 11 speed 105 group so that could be available next year on the Defy but this may also push the price up.

You need to test ride the bikes.


This is a very interesting question. Aluminum vs Carbon. Will it be long before the two are in the same price range - on it's way in the very near future. I have an Aluminum and a Carbon frame road bike. The aluminum bike has a longer wheelbase, more relaxed seat angle (72.5 vs 74 degrees) and square formed stays, and deflects most of the bumps and vibration almost as well as the CF frame.

I'd say geometry, and even more, exact fit, within 1cm or less, are slightly more important than material for comfort, efficiency and handling.

Calculate your frame sized based on Steve Potts bike fit theory. If you are 5'5 or shorter, divide your height in cm by 3.3, 5'6 to 5'10 divide by 3.2, and taller, divide by 3.1 to get your correct frame size. It works.

  • I'd vote this up 30 times if I could. Sep 17, 2014 at 20:41
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    While a good insight, this doesn't really answer the question. Dec 5, 2014 at 21:05

Or, as I have done numerous times, buy a good used bike from a Local Bike Shop that has a good frame that you think you will enjoy long term, and reasonable components. Then you can ride, at a good price, with good stuff, and you can decide what to upgrade and when. Last time I bought a complete bike was 1999. I am riding 3 different bikes right now, a 1998 Merlin Ti, a 2004 Merlin Ti/Carbon and a 2008 Merlin Ti, none of which I paid more than $2300 for, and each are now worth a lot more due to upgrades over the years, on my schedule and budget.

All personal choice, but I've been pretty happy...

  • Welcome to Bicycles SE. While this is certainly a viable alternative, it does not address the OP's question regarding the comparison of carbon and aluminum bikes. This probably would have been better placed as a comment.
    – jimchristie
    Aug 22, 2013 at 21:17

Quality-wise bikes are a lot like chains. The total quality of a bike (where with quality I mean stuff like durability, smoothness, ease of use, ease of maintenance, etc.) is very dependent on the weakest link.

An expensive frame with cheap components makes for a worse bike than a mid-range frame with mid-range components. So given the choice I'd go for the (relatively) cheaper frame with the (relatively) more expensive components, all dependend on what I actually wanted to spend on the bike.

There are "ride quality" differences between carbon and aluminium and steel. Carbon is usually less stiff, so the ride is a bit more comfortable. Steel has the same properties as carbon and is more durable, aliminium is usually a lot stiffer and hence the ride is harsher. For that reason you get aluminium frames with carbon fork and stays. The main disadvantage of steel is of course weight, but you have to look at this critically. The 0.5-1 kg weight reduction you get by going from a really good and durable steel to a carbon frame disappears in the 15-20 kg of fat you are lugging around anyway, and unless you plan to go ride a lot of serious races you will never notcie the small gain of the lighter frame.

Where I'm going with this: In the standard bikes you buy the frame is often of higher quality (and price) compared to the other components. You can get a better bike for less money if you pay attention to this when buying your bike. Spending some time talking this over with you friendly LBS owner will help here.


You are better off buying a Reynolds steel or chromoly steel road bike. Do not believe the hype about carbon fiber. You can buy a steel bicycle just as good or even better than the CF bicycle.

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    It would help if you provided some reasons why (and you didn't answer the question -- it was aluminum vs carbon fiber).
    – Batman
    Nov 20, 2015 at 20:07

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