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Do Carbon Frames degrade faster than Ali Frames?


Cuppa Bru
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I've been a recreational cyclist commutist for a few years and am only recently training harder in the hope of participating in a few races.

So, I've been looking for a nice road bike to replace my bro's Giant Cypress and obviously asked around for opinions.

One guy who seems knowledgeable enough - he had a coach drive behind him in a car shouting at him to go faster when he was training LOL - mentioned that carbon frames lose a lot of stiffness after you crank up lots of km.

He said it was only minimal, like a 0.001% performance drop due to added flex.

Any truth to this?

 

Btw: What's the value proposition of building a new bike instead of buying a 2nd hand bike on the hub? Been looking around and it doesn't seem as though sellers are keen to accept that they probably bought their bicycles at inflated prices and that they can't expect to only take a max 30% hit on their purchase price when *new* bicycle prices are coming down by that rate to come in line with the size of the consumer's pockets after the recent economic carnage(April edition of Bicycling).

 

I just saw last night that I could organise an Ultegra 6700 groupset from cwc for R6999 excl. postage. :)

Does anyone know of any decent carbon frames that are selling? New or second hand. I need to keep the build under R15k, unless I'm to become a weightweenie not by choice but by virtue of not having any spare change for groceries.

 

All explanations and advice very much appreciated.

 

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Carbon frames are much stiffer than Aluminium frames and ride much better.


I suppose it is a personal preference but I would prefer buying new as I then know the history of the frame/bike. Risk of buying second hand is that you don't always know what has happened to the frame before - crashes etc.

It is fine buying the groupset from CWC but can you fit it yourself. I would think that bike shops are not going to be all that impressed if you show up with a box of parts bought elsewhere for them to assemble for you.

You could contact a hubber called Kiwi. I believe he has some nice frames at reasonable prices.
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It is fine buying the groupset from CWC but can you fit it yourself. I would think that bike shops are not going to be all that impressed if you show up with a box of parts bought elsewhere for them to assemble for you.

 

 

 

Nonsense. No bike shop will turn you away to have parts fitted. They will charge you and might not have if you bought the parts from them. If they do turn you away, they should shut their doors because business is business.

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Regarding your question about carbon frames degrading;

It is a fact that some carbon frames do not last as long as Alu frames,seeing as carbon is a fiber which can break down and alu is a metal that does not rust or degrade as quickly. But if you buy a carbon frame from a known brand you usually get a 5 year guarantee on the frame the reason for the 5 years is firstly most cyclists replace their bikes in 5 years and secondly the fact that the frame lifetime on a carbon bike is less.

It might be difficult to justify buying an expensive frame but seeing as almost any "Jan rap" who knows how to work carbon can almost build a frame it is better to go for a brand which has done  extensive testing on their bikes.

You can also search the web there should be allot of answers regarding this matter.


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It is fine buying the groupset from CWC but can you fit it yourself. I would think that bike shops are not going to be all that impressed if you show up with a box of parts bought elsewhere for them to assemble for you.


Nonsense. No bike shop will turn you away to have parts fitted. They will charge you and might not have if you bought the parts from them. If they do turn you away' date=' they should shut their doors because business is business.[/quote']

 

Where did I say they will "turn you away"? Nowhere! Of course they won't turn you away but they not going to be the happiest.
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Carbon does not degrade! in any form or means, yes it fatigues but given an alu frame may have a lifespan of maybe 5yrs a carbon frame will last 10yrs or longer taken there's no external damage.

 

most brands offer a "time limited" waranty because the technology advances at such a rate that after that time period that frame may be so redundant it won't be worth keeping.
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NOTE: From and MTB perspective

 

I now ride a Carbon frame, the gelcoat takes a decent/visible knock from stones and rocks, but in truth after almost a year with this bike and plenty hard kms I can say I am impressed.

 

I ramp off drop off, etc and occasionally bring the tail down harder than I'ld like and it handles it perfectly.

 

I think people have a hard time expecting carbon frames to handle blows like a metal (all be it Alu) frames. Truth be told I think the lifespan is determined by what the frame has been exposed to. Alu can corrode, fall victim to metal fatigure/stress fractures, be dented and bent. However I still lean to Alu frame lasting me longer, but I tend to sell long before either would die LOL. No science in this statement just perception...

 

 

 

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NOTE: From and MTB perspectiveI now ride a Carbon frame' date=' the gelcoat takes a decent/visible knock from stones and rocks, but in truth after almost a year with this bike and plenty hard kms I can say I am impressed. I ramp off drop off, etc and occasionally bring the tail down harder than I'ld like and it handles it perfectly. I think people have a hard time expecting carbon frames to handle blows like a metal (all be it Alu) frames. Truth be told I think the lifespan is determined by what the frame has been exposed to. Alu can corrode, fall victim to metal fatigure/stress fractures, be dented and bent. However I still lean to Alu frame lasting me longer, but I tend to sell long before either would die LOL. No science in this statement just perception...

 

[/quote']

 

 

 

Just for interest sakes. I am in the market and Im pretty convinced to steer clear of carbon.

 

 

 

How much do you weigh?

 

 

 

I weigh 90kg's and have spoken to mates of similar size, the one guy has been through 2 frames already.

 

 

 

I just think that carbon may be better suited to lighter riders (MTB of course)

 

 

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There is no truth (as on none, bugger all, nada, niks) to the rumour that frames "flex" more over time. Not carbon, not aluminium, not steel, not titanium. A frame's stiffness stays the same as the day it was bought, (unless used or stored at temperatures above 150 degrees C).

 

2nd hand stuff is a good idea, if you avoid all the normal pitfalls of buying 2nd hand stuff. My general rule of thumb is not to pay more than 50% of the new price from totalcycling.com or chainreactioncycles.com, unless the stuff is almost brand new. Agreed, some 2nd hand prices are quite crazy. 
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get a giant it will never break and its a good frame,stiff,strong and climbs realy nicely =)

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What size bike do you ride, there i a Cannondale 54 on the hub, for a very good price. 

 

I would have bought it, if it was a 56, but a 54 is to small for me.

 

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Thanks for all the replies! The hub really could have some Lance Pharmstrong's if you spent all the time you're on the hub on the saddle instead lol

 

 

I always thought carbon frames were crazy strong and didn't understand why they'd lose any of that strength. But I've heard that when they do fail they fail catastrophically. And the guys at Bruce Reyneke's (might be biased) claimed that climbing on a Raleigh carbon bike was the equivalent of doing kamikazi. ?!

 

Sylvester, I'm probably a size 54, seeing as I'm 1.79m. But I've been riding my bro's 10-year-old 21" Giant Cypress for the past 2 years to varsity and back and for training the past 2 1/2 months, maybe I stretched my legs and will never fit on a normal sized bicycle again lol.

I got an awesome contact at Silverton Cycles, and he helped to replace the crap that was on there with a configuration that needs a diesel-motor to push through the gears and introduced me to cleats lol  But I want something more purposefully built that sounds clean when the chain runs over the gears and might prevent those guys on their R100k bicycles from overtaking me on George Storrar on the downhill when I'm pedalling and they're not lol.

Please send me a link to that Cannondale. I might've seen it already, as I've been following the classifieds like Putin watches over "his great, free people" :D

And yeah, I don't see how some sellers believe they're justified in asking almost new prices for used bicycles(some 2006/7 even).

 

Now that I've hijacked all this bicycle gear brainpower on the technical side of the forum, I'm going to take a chance and ask all of your collective bicycle brainpower to point me towards a sweet bike (sub 10-15k) and a serious cycling group in Pretoria-East :)

I've only ever competed in one bicycle race and that was when my cuz got me to do the 94.7 with him in 2008 - which rocked if it hadn't been 3h50min in the midday freaking sun! But cycling through Jhb CBD and over the Mandela Bridge was quite something :)

 

I was going ape-sh*t on my bro's bicycle for 2 months averaging about 2 hours in the mornings and 1 hour at night before I caught H1N1's big bad brother two weeks ago and which had a vice grip on me til today - doc said yesterday: "no cycling til monday" :(

 

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Eggpurts abound .... lol?

Well let me add my 2c on the subject: as I understand it, Al frame are metal. All metals suffer from fatigue. That is the crystaline structure which gives it its strength starts to breakdown if its bent/stressed enough.? Especially Al. But add some alloys, and it gets better, but bend/stress it enough and it will fail. Aircraft Al airframes have limited hours for this reason. ?Metal Fatigue was the tragic lesson learned by a number of Vickers Viscounts falling out of the sky in the 50's?

Carbon Fibre and Composite frames are a different story. They retain strength and form under repeated stressing and bending. Take a look at the carbon chanstays of a Cannondale Scalpel (my 2005 model? if u like). There is a flexible flattend tube bit that the swing arms swivel on. Try do that with Al and it will fail in no time. Over a longer period of time, I dont know about carbon decay but it can be answered by the aircraft technology once again: more and more of airframes are composite carbon (the 787 especially).?

But a carbon structures problem is that if its subject to forces outside of ?places/planes where it was designed to handle load or impact, it will snap and break like a matchstick. You see this with some road bike prangs, and also famously when a American Airlines Airbus (carbon) tail fin broke off ?from vortex turbulence over Long Island in 2001, and the aircraft came down.?

Also the Columbia Space Shuttle: the leading edge was carbon which could handle the heat of reentry and all the aerodynamic loads, but shattered when a suit case suize piece of foam hit it.

Its possible that these stories of limited life span of carbon bike frames? are invented by those who like the idea of planned redundancy for commercial reason ( as has proved to be a succe$$ with Microsoft et al in the IT industry)

?

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2 possible groups in Pta East:

 

1. Velo club is probably the largest, & their "A" bunch the strongest.

Rides are from corner of Hans Strijdom & Attebury, see www.velo.co.za for details. Anybody welcome, and they won't ever pressure you to join. Just be warned, at times the pace of the A bunch is quite insane (the record is 43.7km/h average for the Tuesday morning club ride.) They usually have a slower bunch, too.

 

2. Select is perhaps a smaller club, and rides from Bruce Reyneke's shop in Lynwood rd.

They have a nice hilly route for their Saturday rides. I have not ridden with them for a while, but they also have 2 of 3 groups. "A" bunch pace a bit easier on the legs compared to Velo.

 
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  • 2 months later...

Hi All

 

I am in the carbon fiber manufacturing and repair business for over 20 years now and can only confirm that metal will die of fatigue far before carbon will show any signs of degradation.

We repair about 50 carbon frames a year and never had a case were the material got tired. The majority of damages are due to an accident or rough handling in transport.

generally one can say that if one looks after the bike and protects the exposed areas from small stone impact, the frame will last forever.

We use a fairly cheap clear tape on a roll, that can be replaced easily.

Cheers

 

Arno

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