ALUMINIUM VS CARBON FIBRE

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ALUMINIUM VS CARBON FIBRE

Postby dan97 » Fri Jul 13, 2012 11:56 pm

Hello Guys continuing with my "New to Cycling" discussion, i want to find out more about the best to buy.

So Aluminium or Carbon Fibre?
Of course this sounds like a stupid question, but surely there must be more to it than "Carbon Fibre is lighter = Carbon Fibre is better"
What are the Pros and Cons of Aluminium and also Carbon Fibre?

Thankyou
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by BNA » Sat Jul 14, 2012 12:45 am

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Re: ALUMINIUM VS CARBON FIBRE

Postby pawnii » Sat Jul 14, 2012 12:45 am

The only benefit to aluminium framesets is price :P
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Re: ALUMINIUM VS CARBON FIBRE

Postby arand18 » Sat Jul 14, 2012 7:56 am

A high end aluminium frame will outperform a low end carbon fiber frame.
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Re: ALUMINIUM VS CARBON FIBRE

Postby Nobody » Sat Jul 14, 2012 8:32 am

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Re: ALUMINIUM VS CARBON FIBRE

Postby AndrewBurns » Sat Jul 14, 2012 9:13 am

Nobody wrote:Image


A subjective table produced by a company that makes titanium bikes, and what do you know titanium is the only material recommended for everything!

As with every time this comes up, as far as 'feel' goes the material the frame is made of is secondary to the geometry of the frame, the construction and thickness of the tubes, the wheels, the tyres, how much air is in the tyres etc. Carbon fibre weight-for-weight is stronger than steel or aluminium so it's possible to make a carbon frame lighter than a steel or aluminium one for the same strength but that's about as far as you can take it, basically anything else that determines how well the bicycle operates and how it feels is dominated by other factors.
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Re: ALUMINIUM VS CARBON FIBRE

Postby Nobody » Sat Jul 14, 2012 9:53 am

AndrewBurns wrote:A subjective table produced by a company that makes titanium bikes, and what do you know titanium is the only material recommended for everything!
Actually magnesium appears to be the favorite if you ignore durability (which most people do anyway). Having said that, Zinn has an international reputation to keep, so it isn't in his interests to lie.

AndrewBurns wrote:As with every time this comes up, as far as 'feel' goes the material the frame is made of is secondary to the geometry of the frame, the construction and thickness of the tubes, the wheels, the tyres, how much air is in the tyres etc.
Geometry for the same kind of bike would be virtually the same. As for wheels and tyres etc, although true collectively, that's not what the OP asked.
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Re: ALUMINIUM VS CARBON FIBRE

Postby trailgumby » Sat Jul 14, 2012 1:22 pm

AndrewBurns wrote:A subjective table produced by a company that makes titanium bikes, and what do you know titanium is the only material recommended for everything

Andrew, you've fallen prey to what CS Lewis calls Bulverism - the view that because someone can be perceived to have an interest in an outcome, nothing they say can be trusted.

Running with that view, I could just as easily say that you have an interest some other material being best because that's what you own, so whenever somebody contradicts you. you go into denial and therefore can't be trusted either. I call BS on that: where does it end? It ends with there being no such thing as *objective* truth (supposedly) because it's all subjective and everybody makes up their own. To that I say have fun making up your own rules with gravity. :P

With respect, I suggest it's equally likely that Zinn makes titanium frames *because* they are the most durable. He also makes frames in aluminium (mtbs only by the look of that diagram) and steel.

He's been in the industry for yonks, has a number of (outstanding) books published, including Zinn and the Art of Mountain Bike Maintenance, Zinn's Cycling Primer, et cetera, so his "brand" if you like is his pull-no-punches accuracy and technical nouse.

So I don't see him sacrificing that just to sell a few frames, especially when if something else is stronger it's a relatively simple matter to just use that material instead... even with carbon.
Last edited by trailgumby on Sat Jul 14, 2012 7:49 pm, edited 1 time in total.
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Re: ALUMINIUM VS CARBON FIBRE

Postby gururug » Sat Jul 14, 2012 1:41 pm

It's funny these threads come up so much. I'm thinking the shops try to get everyone to buy carbon higher end bikes by outlining the benefits of carbon and as a result making aluminium out to be, "heavy" or "non-compliant".

If your new, it's about the particular bikes handling properties. Carbon bikes that ride like bricks and alu bikes that ride like pro level bikes are available.

Most people who ask this question are really asking......"Will it be worthwhile me forking out an extra $1000 for a carbon because it will be a featherweight and handle like a ferrari". The answer is no. Take each bike on it's merits ( weight / components / geometry ) and go from there.
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Re: ALUMINIUM VS CARBON FIBRE

Postby Mulger bill » Sat Jul 14, 2012 2:28 pm

The simple answer is "There is no simple answer"

Eaqch frame material has its pros and cons: Cf is brittle, Fe is heavy, Al probably had a bogan sucking Jack and cola out of it six months ago and Mg will catch fire if you ride too close to the sun. Even the things AB alluded to are relatively small change.

The really important things in a bike are YOUR seven points of contact, (two hands, two feet, one brain. one heart and one bum) and how they merge with a bike to create that magnificent cyborg. Get it right and your world is a place of constant wonder and delight, get it wrong and you may as well have stood in the street handing out fiftys to random passers by.

To sum up, forget what it's made of, what colour it is or if it has the right "europro cred". If it appeals to your heart, sit on it for an hour or so and let the other six points have their say. If they all agree, come back tomorrowfor another try. If, when it's time to leave the shop you stop and turn back for a last look then you've found the right bike for YOU.
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Re: ALUMINIUM VS CARBON FIBRE

Postby dan97 » Sat Jul 14, 2012 3:16 pm

Where can you get Magnesium frames?

I currently have two steel bikes. I think they're awesome but i have never had anything else!
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Re: ALUMINIUM VS CARBON FIBRE

Postby Nobody » Sat Jul 14, 2012 5:34 pm

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Re: ALUMINIUM VS CARBON FIBRE

Postby pawnii » Sun Jul 15, 2012 12:49 am

My 2cents.

CF is brittle but repairable. Once you damage Al you'll never get it back to it's original state.
If you drop and damage a road bike at 40+km/h, it's cactus regardless if it's made from CF or AL.

CF doesn't fatigue through compression and tension. All other materials do over time.
CF has the highest stiffness to weight ratio.

There has to be a reason why every single pro bike on the road and track is made from CF. Can't just be marketing right?

I do agree that a top of the line Ti or even Al frameset is better than a cheap CF frameset, but that's not comparing apples with apples is it?
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Re: ALUMINIUM VS CARBON FIBRE

Postby Nobody » Sun Jul 15, 2012 9:26 am

pawnii wrote:CF is brittle but repairable. Once you damage Al you'll never get it back to it's original state.
Gripsport would probably disagree with you, but I wouldn't bother repairing Al as the frames I buy are usually cheap.

pawnii wrote:If you drop and damage a road bike at 40+km/h, it's cactus regardless if it's made from CF or AL.
Depends on how sudden the stop was. I'd prefer Al if I still had to ride it to get home.

pawnii wrote:CF doesn't fatigue through compression and tension.
I don't know where you got this idea from, but this study does not support it.
http://www.google.com.au/url?sa=t&rct=j ... jg&cad=rja

pawnii wrote:All other materials do over time.
You obviously need to do a bit more reading.
Image
http://en.wikipedia.org/wiki/Fatigue_limit

pawnii wrote:There has to be a reason why every single pro bike on the road and track is made from CF. Can't just be marketing right?
Well, there is the marketing argument that bigger tubes and higher profile rims can hold bigger lettering for advertising, whether that be for just the bike model or something else. Many years ago you couldn't even see the make & model of a rim without a close inspection, now it's very obvious when stationary. I was on the Sydney northern beaches this morning at the lights and could easily see the frame brands as they rode past me.
As for marketing:
http://www.bikeradar.com/news/article/d ... ikes-32076

To me, it doesn't really matter if every pro rides carbon. Pros are given bikes to ride and have replacement bikes on standby. I live in the real world of limited budgets and having to wait weeks for a warranty claim, so I prefer real-world durability.
Last edited by Nobody on Mon Jul 16, 2012 9:14 am, edited 1 time in total.
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Re: ALUMINIUM VS CARBON FIBRE

Postby Mulger bill » Sun Jul 15, 2012 11:32 am

Nobody wrote:
pawnii wrote:There has to be a reason why every single pro bike on the road and track is made from CF. Can't just be marketing right?
Well, there is the marketing argument that bigger tubes and higher profile rims can hold bigger lettering for advertising...

Well I'll be... Been perving at passing pushies for years and that thought never entered me mind :oops: Sorta explains the modern practice of "LOOK at my GIANT logos" covering nearly every surface.

pawnii wrote:There has to be a reason why every single pro bike on the road and track is made from CF. Can't just be marketing right?
Nobody wrote:To me, it doesn't really matter if every pro rides carbon. Pros are given bikes to ride and have replacement bikes on standby. I live in the real world of limited budgets and having to wait weeks for a warranty claim, so I prefer real-world durability.

+ As many as you like and a little bit more. Pros race whatever frame the equipment sponsor provides.
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Re: ALUMINIUM VS CARBON FIBRE

Postby pawnii » Sun Jul 15, 2012 11:31 pm

pawnii wrote:
CF doesn't fatigue through compression and tension.
I don't know where you got this idea from, but this study does not support it.
http://www.google.com.au/url?sa=t&rct=j ... jg&cad=rja
I'm not about to read over 40 pages on CF fatigue. But the point i'm trying to make is (applying only to bikes) the flex or deflection you get in a CF frameset will always return to it's original position so you'll never have a twist or buckle in the frameset. If enough stress is put on CF it'll fracture or shatter but other than that happening the frame will be as good as the day it was made.

Depends on how sudden the stop was. I'd prefer Al if I still had to ride it to get home.

True but I wouldn't choose an Al bike for this reason.

Regardless of marketing, font size and tube size, isn't a stiffer, lighter and more aerodynamic bike faster? I hope so, cause this is what I've based all whole understanding of a fast bike on. :shock:

I can't help but think all the bikes you see on The Tour are fantastic. I know the riders ride whatever they're given and the bike companies market the hell out of there product but I don't think any Aluminium bike would better them.
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Re: ALUMINIUM VS CARBON FIBRE

Postby Nobody » Mon Jul 16, 2012 7:39 am

pawnii wrote:I'm not about to read over 40 pages on CF fatigue. But the point i'm trying to make is (applying only to bikes) the flex or deflection you get in a CF frameset will always return to it's original position so you'll never have a twist or buckle in the frameset. If enough stress is put on CF it'll fracture or shatter but other than that happening the frame will be as good as the day it was made.
Well if you're not willing to read, it is harder to learn.
According to what I've read, no frame is as good as the day it was made, but Ti and steel are a lot closer than any other commonly used frame material if not overstressed.

pawnii wrote:
Nobody wrote:Depends on how sudden the stop was. I'd prefer Al if I still had to ride it to get home.
True but I wouldn't choose an Al bike for this reason.
I woudn't just for that reason either, but it isn't the only reason to buy Al.

pawnii wrote:Regardless of marketing, font size and tube size, isn't a stiffer, lighter and more aerodynamic bike faster? I hope so, cause this is what I've based all whole understanding of a fast bike on. :shock:
Yes, but your overplaying the bike's role. As you would know, it's the person with the biggest engine to body frontal area on the flat or biggest engine to body weight up the hills. The best rider on a $1200 Al bike will still win the road race.

pawnii wrote:I can't help but think all the bikes you see on The Tour are fantastic. I know the riders ride whatever they're given and the bike companies market the hell out of there product but I don't think any Aluminium bike would better them.
And Al bikes wouldn't be worse either to the point of changing the results of any group race.

It is clear that pro-rider marketing works and the manufacturers are pushing carbon as the superior product. These bikes suit people at the pinnacle of their sport (with the associated manufacturer support). For the rest of us, any metal bike would be a good alternative due to better real-world durability, better failure mode and (in most cases) cheaper cost.

For the extreme example, if I were to take a $10K+ carbon road bike setup the same as my own bike and race it over the same course, everything else being equal, the timed difference would be very small. Whether this extra time is worth paying four times as much for is up to the individual, but I would cite that the added value seen by the purchaser of such a bike is mainly emotional.
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Re: ALUMINIUM VS CARBON FIBRE

Postby dan97 » Mon Jul 16, 2012 9:15 pm

I hope i am not creating any problems with my post

Remember everyone is entitled to an opinion. I respect everything EVERYONE says because as you know i am new to this sport.
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Re: ALUMINIUM VS CARBON FIBRE

Postby Nobody » Mon Jul 16, 2012 9:46 pm

dan97 wrote:I hope i am not creating any problems with my post

Remember everyone is entitled to an opinion. I respect everything EVERYONE says because as you know i am new to this sport.
You are not directly creating problems. :)
This type of thread gets aired about once a month and often has similar posters saying similar stuff. Nothing new. These types of threads often can get a bit heated as some take it more personally than others. Business as usual. Here's an earlier one on frame materials, but about high-end steel:
viewtopic.php?f=34&t=51878

As per Trailgumby's signature (above)...people are entitled to their own opinions, but not their own facts...
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Re: ALUMINIUM VS CARBON FIBRE

Postby Mulger bill » Mon Jul 16, 2012 11:00 pm

No Dan, you're not. You are young and want to learn, I for one applaud it and will do all I can to assist either by sharing what little knowledge I have or slapping people who aren't helping. It pains me to think that some unthinking posters might be in some way reducing your enthusiasm with argument or ad hominems instead of information or discussion. I wish they'd take it elsewhere.

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Re: ALUMINIUM VS CARBON FIBRE

Postby Nobody » Mon Jul 16, 2012 11:15 pm

Thanks Shaun for your action. :)
I would like to have a vocabulary like yours. I had to look up Ad hominem. :oops:
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Re: ALUMINIUM VS CARBON FIBRE

Postby jacks1071 » Tue Jul 17, 2012 1:09 am

pawnii wrote:The only benefit to aluminium framesets is price :P


Is that so?
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Re: ALUMINIUM VS CARBON FIBRE

Postby pawnii » Tue Jul 17, 2012 2:16 am

just kidding Jacks.
I have no idea what the benefits of an aluminium frameset is over a carbon one.
I just love my carbon bike. I better leave this discussion to the experts.
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Re: ALUMINIUM VS CARBON FIBRE

Postby Chris249 » Tue Jul 17, 2012 1:10 pm

I'm no engineer, but in the past I have interviewed quite a few engineers about carbon construction and durability.

FWIW the linked paper appears to clearly show that 90/0 degree carbon (AKA as isotropic or unis IIRC) has very good fatigue resistance, which accords with everything I've heard from engineers working in the field. The report notes that for 90 degree (aka unis or isotropic IIRC) fibres "the composite is highly fatigue resistant in the O/90”
direction, especially at room temperature. The stress levels involved are close to the ultimate strength,
indicating that fatigue is unlikely to be a problem when cyclic stresses coincide with the fiber orientation.....In design criteria for cyclic loadings, it is desirable to ensure that the stiffness loss during cycling does not exceed 10%. The data presented in Appendix B indicate that the stiffness loss in O/90” specimens remains well below 10% all the way to failure."

The paper mentions that 45 degree carbon has much greater issues than 90/0. However, it specifically mentions that it is testing carbon parts built by a (production) auto-engineering process that is (as it mentions) quite different to aerospace techniques. The test parts are cured in only 2.5min, plus some post-cure time, as one example. As far as I can recall, good carbon bikes are built to techniques closer to aerospace than to auto engineering.

So the report just backs up everything I've read before, which is that good carbon well done (i.e. properly designed with attention to load paths and fibre orientation, cure times etc) is fantastic, has great fatigue life and is basically completely repairable, but "bad" carbon isn't that good.

Guys in charge of building multi-million buck carbon structures that form the basis of $25 million buck pro sailing campaigns, where forces are measured in scores of tons, have said to me on the record that they believe that good carbon construction may have NO effective fatigue limit. And the top guy who said that is an expert in timber construction, and could actually probably earn more if he was still building top-line wooden racing boats (which are more labour intensive and require less investment in autoclaves etc) so he probably doesn't have a commercial axe to grind.

Sailors who are doing world title campaigns in carbon boats say that one of the benefits of carbon is that it's very repairable, which fits into everything I've been told by people like a carbon engineer I ride with, who fixed my Zipp rear wheel - and rides a carbon bike! Ironically, although I have no issue with carbon's strength, I ride 4 alloy frames; one with top-line 90/0 fibre carbon forks, one with cheaper 45/45 carbon forks, one with chro-mo forks and one with alloy forks.

I don't know about many "real world" problems with carbon; I was a courier and have spent years commuting with never a dent or significant broken part while riding, so can't see how much of a problem carbon's low impact resistance can be. Ironically my good bike's forks were smashed, apparently by a car when the bike was locked to a lamp post and the front wheel was off. I didn't notice the damage until it went in for a service about 1k riding later, when they drew my attention to the crack that ran all the way across the inside of the fork and around the front and back edges. Although by luck I was taking the bike in for service anyway, the point is that despite severe damage the high-quality Cervelo fork did not fail catastrophically and I can have it repaired for about $60.

FWIW I've gotta agree with Nobody's post where he points out that basically it's all about the rider, not the bike.
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Re: ALUMINIUM VS CARBON FIBRE

Postby Nobody » Tue Jul 17, 2012 2:32 pm

Chris249 wrote:Guys in charge of building multi-million buck carbon structures that form the basis of $25 million buck pro sailing campaigns, where forces are measured in scores of tons, have said to me on the record that they believe that good carbon construction may have NO effective fatigue limit.


:P

Chris249 wrote:I don't know about many "real world" problems with carbon
But there are plenty of examples of people who come on here to say their frame has cracked or know of people who's frame has cracked (both Al and CF). Many don't treat it as a big deal due to lifetime warranties and free upgrades. And for the most part, it isn't for frames, due to almost all not causing a crash. However, for the small amount of advantage a lighter bike gives, I don't think it's worth the extra care, cost and warranty wait. Crashes are a whole different story as a carbon bike will often break (adding to the risk of injury) where a metal bike will most likely bend. You would know from windsurfing and sailing how a carbon mast fails. A crash on either type of bike may lead to repair or replacement, but generally Al is much cheaper to replace. I would argue that if you can't afford to easily replace a bike, you can't afford to own it either (and no, I don't insure my bikes).

As for ease of diagnosis after a crash, even Trek think they need to put a warning out. The "Caring for the Carbon Steer Tube on Your Fork" also shows how easy it is to get carbon assembly wrong, therefore increasing the risk of failure on a safety-critical point of the bike.
http://www.trekbikes.com/faq/questions. ... stionid=96

Chris249 wrote:FWIW I've gotta agree with Nobody's post where he points out that basically it's all about the rider, not the bike.
At least we can agree on something. :)
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Re: ALUMINIUM VS CARBON FIBRE

Postby dan97 » Wed Jul 18, 2012 10:42 pm

In conclusion

Aluminium or Carbon?

Lets say i have a budget of $1500
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