Carbon vs Aluminum

Aluminum : Works well with a good aluminum. For me, Specialized E5 Alu has been the best ever.

Carbon : Now a must for me. I switched from Spec. E5 alu to Spec. S-Works Tarac SL full monocoque carbon and I still don't beleive it... It is such a ride !!!! If you can afford carbon, go for it !

Be warned though that (IMHO), between a 1500$ carbon bike with poor components and poor wheels and a well mounted alu bike for the same price, I would rather choose the alu bike. Look at the components, especially the wheels, that might make a good difference...

good luck !

Christian. 

To start, everyone has there own opinions on what works best for them.  This is just my opinion stated and I've talked to many other friends and riders who have agreed.  In the end it's all personal preference and I would go out and test ride bikes.  It's worth your time. 

1) In terms of life expectancy, Aluminum will have a longer life than carbon. Depending on your weight and type of riding (are you a stomper, do you race, etc) >> then carbon has a rather limited life. Most of the terrible things about carbon frames have been corrected. The trek OCLV for example used to have terrible frame problems early in their lives. Aluminum will still last much longer. carbon can lose its already soft feel over time. Aluminum keeps its ride characteristics well over time.

2) Performance. i've ridden on both material , and both frames are toublesome if you crash. Yes, with Aluminum you will need your carbon accessories (seatpost, fork, stem) to dampen road chatter. Unless you ride on perfect roads, it will be harder to get a smooth ride (harder, not impossible)
When you stand and really get after it, an Aluminum bike feels like its using all your powerstrokes>>over time Aluminum will stand up to this test.

3) road conditions. see #2.

The weight differences are negligible.
Longevitiy issues are next up. I see a lot of Aluminum bikes on ebay. They have good resale value. I am always leary of used carbon. I'm leary of the change in joint strength over time.

I hope my opinion helps.  Cheers

I was asking about the same thing back in March 2007 - here's the thread:
http://www.beginnertriathlete.com/discussion/forums/thread-view.asp?tid=65332&posts=11&highlight=carbon&highlightmode=1#M714989

You might be able to find some additional comparisons by using the Search Forums area if you want if you don't want to wait for responses:
http://www.beginnertriathlete.com/discussion/search/query.asp

Google is your friend, too, and can provide a number of hits (here's one):
http://forums.roadbikereview.com/showthread.php?t=37770

One big difference is cost - carbon (composite) is a little more pricey.  I'll let others weigh in about maintenance, comfort, etc.

I have an aluminum frame on my tri bike and carbon frame on my road bike. 

I much prefer riding the carbon frame.  The carbon is more comfortable, but very responsive.

However, one of the cool things about carbon is that its characteristics can vary (e.g., stiffness versus flexibility) depending upon how it is built.  So if you are looking at carbon frames, find one that is made for your needs and try a few out.  Mine is made to be very stiff, but not everybody likes that.

It's true that carbon isn't the most durable of materials. I just had to replace a frame a little over a month ago after mine was fractured in a crash.  I don't think an aluminum frame would have held up in that particular situation either though.  Steel or titanium are the way to go if durability is a priority.

"1) In terms of life expectancy, Aluminum will have a longer life than carbon. Depending on your weight and type of riding (are you a stomper, do you race, etc) >> then carbon has a rather limited life. Most of the terrible things about carbon frames have been corrected. The trek OCLV for example used to have terrible frame problems early in their lives. Aluminum will still last much longer. carbon can lose its already soft feel over time. Aluminum keeps its ride characteristics well over time."

As an engineer who works with these materials, I can tell you that these statements sound good, but are completely false. In fact, pretty much the reverse is true.

Steel and titanium have a "fatigue limit", meaning that there's a stress level that, as long as you stay under it, will allow that material to have an infinite life. Aluminum does NOT have a fatigue limit, meaning that no matter HOW low the stress level, it WILL fatigue and eventually fail. That "eventually" may be a very long time, but it will still happen (and the higher the stresses, the sooner that will be).

Carbon doesn't fatigue at all, but it IS very susceptable to impacts across its laminate (like a pump falling on a frame tube). Old failures of carbon frames were related to the bonding of composite tubes to aluminum lugs (and even those bonding problems have been ironed out).

I am leering of buying used aluminum OR carbon, for the reasons above. But that is my personal opinion.

As I always say ....... any material can be made to have just about any specific ride characteristics (within reasonable limits) ...... it all just depends on the manufacturer and the frame design.  You can make an aluminum frame whippy (think Vitus from years ago) and you can make a carbon frame stiff as hell (the beefier Colnago C50's or current Giant TCR Limiteds).

The life expectancy for aluminum frames used to be only about 4 - 5 years and that was how long most manufacturers would warranty them for because of that.  Carbon was similar but that was more because of the way they were layered and bonded more than anything else.  Both types of materials have come a long way even in just the last 10 years.

I personally prefer carbon over aluminum by a long shot, but that is more than likely because of the sour taste aluminum has left with me from my years of selling bikes in shops and riding/racing them back in the 90's and because of the responsiveness, weight and design of the two I currently own.  I really prefer steel, but it is getting harder and harder to find good light steel frames that can even come remotely close in weight to the carbon/aluminum/ti frames of the current production levels.

Wow ....... that is probably one of the only times I've ever heard that ........ compliant was pretty much the LAST thing I'd ever say about a Cannondale to customers (even when I sold the brand).  Unless they've changed over the years they were the stiffest and most "fragile" of all the aluminum frames I dealt with.

Can you engineers explaing the "fatigue" to me?  Do you mean the frame will actually break or that it will lose it's rigidity?  How would one know when their frame has fatigued?   I have a 10yo Alum MTB frame that still seems great to me.  

Here is a good example of a rupture from fatigue. My alu bike broke on the chainstay near the cassette after about 20000km. Fatigue is  caused by the loss of ductility from the materials after a certain amount of stress cycles... Carbon is not likely to do that, having a much better resistance to fatigue...

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I am not a metalurgist or a structural engineer but I do love bikes.  I have two aluminum bikes.  One is a Pecco Eclipse with no carbon and it is a bit rough after a few hours.  My other bike, a P2SL with carbon fork and carbon seat post is as smooth as silk.  I don't know shite about structural fatigue but my 1998 Eclipse with welll over 30,000kms on it is fully intact and still rides very well.  

 Never mind trying to analyse the situation to death.  Just go to the bike shops and try out alu and carbon bikes in your price range.  Your body ... and most especially, yourbutt ... will tell you which bike is best for you.

Besides a good deal, this is the primary reason I went Ti.  That frame should last my entire life.....