Yet another reason to avoid carbon frames

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The utility cyclist
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Re: Yet another reason to avoid carbon frames

Postby The utility cyclist » 4 Sep 2020, 5:25pm

fastpedaller wrote:
pliptrot wrote:
But the fog of marketing and the lack of clarification about materials, processes, and so-on make most us suspicious. It is normal when someone is selling something with an advantage that they promote that advantage heavily. I have yet to see that with carbon fiber; weight aside.


From my perspective, the threat of a sudden breakage from CF would make me wary about buying one. The QC control is what matters, and how can one tell if the resin/fibre is as it should be, especially on critical regions like head tube/downtube? With a steel frame these regions are, of course, equally critical, but with a handbuilt frame and a skilled builder one would expect the joints to be good. The extended temperature tollerance of more recent tubing compared with say 531 possible suggests a failure is even less likely?

What sudden threat of breakage? :? You're not one of those that thinks CF simply melts in the sun or breaks merely by giving it a dirty look are you? In some instances carbon fibre is far more resilient than steel, alu or titanium, in a front on incident I'd rather have carbon forks/frame than steel or alu.

I presume you've seen this right? I'm glad I have a MTB grade gravel/touring/do whatever frameset, it's the same grade CF as that used by the World Championship winning XC bike 10 years back.
Having bunfortunately been on the wrong end of a hit and run and other motorists induced incidents none of the CF components or CF frame parts managed to break. I just go by my own personal experience of using the material on an almost every day basis over the last 11 years.

peetee
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Re: Yet another reason to avoid carbon frames

Postby peetee » 4 Sep 2020, 7:56pm

I’m not convinced the first test in that video proves anything. Well before the fracture occurs random crackles consistent with delamination can be heard. I wonder how long the frame would have withstood half the terminal pressure if it had been left loaded for some time or, more pertinently, loaded repeatedly.
Last edited by peetee on 5 Sep 2020, 5:56am, edited 1 time in total.
Winter had arrived in the land of Kernow. Along with it came wet roads and cool winds.
“Oh, my wheels and coupling rods!” Peetee exclaimed.

rogerzilla
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Re: Yet another reason to avoid carbon frames

Postby rogerzilla » 4 Sep 2020, 9:26pm

CF frames are lightest. That's about it, really. I have 40 lumpy miles to do tomorrow morning. I have a choice of steel or carbon road racing bikes. Same position, same design purpose, almost 4lb weight difference. But the steel one is nicer to ride (it twangs over bumps rather than crashing over them) and it's silent; a CF frame is a soundbox.

I'll take the steel one.

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The utility cyclist
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Re: Yet another reason to avoid carbon frames

Postby The utility cyclist » 6 Sep 2020, 7:51pm

rogerzilla wrote:CF frames are lightest. That's about it, really. I have 40 lumpy miles to do tomorrow morning. I have a choice of steel or carbon road racing bikes. Same position, same design purpose, almost 4lb weight difference. But the steel one is nicer to ride (it twangs over bumps rather than crashing over them) and it's silent; a CF frame is a soundbox.

I'll take the steel one.

It sounds like you haven't set the carbon bike up correctly for the intended use/bike load, I also have a steel racing frame plus a pottering retro, two Titanium, two alu-carbon and two full carbon, my carbon racer is fastest and significantly lighter than the steel one (Vitus triple butted), it's bloody lovely over the roads, I can do 50 miles in under 3 hours solo without absolutely caning it. The only real differences I might feel is when I adjust tyre size/pressures and body position.
My CF frame is quiet as anything, just the swish of the bladed spokes, maybe you bought a wrong un?

PaulS
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Re: Yet another reason to avoid carbon frames

Postby PaulS » 8 Sep 2020, 10:55am

Brucey wrote:As a materials scientist, I know a fair amount about the virtues of different materials. CF (in its various forms) can indeed be a wonderful material. However in the real world, there are problems. Problems so bad that they kill people.

Other problems are that the sort of CF that infests the cycle market can be pretty crappy, and they are in no way designed to be subjected to UK winter conditions (hence the OP's situation, which is not uncommon). Fatal exceptions such as (invisible until it breaks) steerer failures which happen ahead of other problems in CF framesets have yet to be weeded out.


Regarding winter. Is carbon uniquely bad for UK winters, or is it just the typical design of carbon frames? And does that also mean that carbon forks or carbon/aluminium forks are uniquely bad for winter too?

My idea of a winter bike (and next project) needs mudguards, dynamo lighting, disk brakes, and clearance for spike tyres. Nothing to rule out carbon so far. And the trend for gravel bikes and disk brakes gives lots of frame options to suit bigger tyres. (CJs Holdsworth is inspiring, and Spa's Elan looks great too)(last year I used a Raleigh Sojourn which was ok)(Bob Jackson only go to 32mm tyres, and Mercian have a waiting list till Spring).

bgnukem
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Re: Yet another reason to avoid carbon frames

Postby bgnukem » 8 Sep 2020, 5:05pm

I'm curious too, regarding the causes of carbon failure beyond hidden impact damage or abrasion damage.

Also why our winters would be bad for a carbon frame. I assume we are talking salt corrosion of the metal bits attached to the carbon, e.g. BB shells, dropouts, ali fork steerers?

is UV exposure in summer an issue, or does the gel coat (correct name?) have UV blockers in it? Does the heat generated by exposure to the sun cause any damage?

Not owned a carbon bike yet but I admit the weight saving would make one attractive.

tim-b
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Re: Yet another reason to avoid carbon frames

Postby tim-b » 8 Sep 2020, 6:37pm

Hi
bgnukem wrote:I'm curious too, regarding the causes of carbon failure beyond hidden impact damage or abrasion damage.

Also why our winters would be bad for a carbon frame. I assume we are talking salt corrosion of the metal bits attached to the carbon, e.g. BB shells, dropouts, ali fork steerers?

They suffer with galvanic corrosion in much the same way as any other frame fitted with dissimilar metal parts. Prevention is the same, isolate the dissimilar materials either in construction using a neutral fibre, e.g. GRP, or use a CF assembly paste. Wash the bike and occasionally disassemble to regrease (repaste?)
is UV exposure in summer an issue, or does the gel coat (correct name?) have UV blockers in it? Does the heat generated by exposure to the sun cause any damage?
Not owned a carbon bike yet but I admit the weight saving would make one attractive.

CF by itself doesn't corrode and is resistant to high temperatures but the epoxy or other matrix can fail due to UV or temperature. A UV resistant clearcoat or paint is used and CF matrices should be designed for a "normal" cycling temperature range. CF has been combined with a polymer matrix to replace steel con rods in a car engine
Regards
tim-b
~~~~¯\(ツ)/¯~~~~

PaulS
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Re: Yet another reason to avoid carbon frames

Postby PaulS » 8 Sep 2020, 8:47pm

The details and photos for the Holdsworth Mystique says it is fitted with low-rider rack mounts. But talking to Planet X they advise against the use of fork mounted pannier. Probably sensible, but a shame. I need a rear rack, and a front option might be a nice extra.

Carbon fibre (and glass fibre) is popular and well characterised for boats and fishing rods used for salt water and high UV exposure. So the problem cannot be with the material. It is popular for racing cars and aeroplanes too.

Brucey
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Re: Yet another reason to avoid carbon frames

Postby Brucey » 10 Sep 2020, 11:09pm

ritchey saddle/seat pin manual;

https://eu.ritcheylogic.com/eu_en/magb1/download/index/type/catalog_category/id/4/

the section on 'special characteristics of carbon' is interesting

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

jb
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Re: Yet another reason to avoid carbon frames

Postby jb » 11 Sep 2020, 8:00am

They've sold it to me; a whole three years use and meantime the slightest fart & I have to take it back to a Richey dealer for inspection.

Even accounting for over the top safety manuals Its a little off putting reading all that.
Cheers
J Bro

tim-b
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Re: Yet another reason to avoid carbon frames

Postby tim-b » 11 Sep 2020, 8:02am

Hi
Brucey wrote:ritchey saddle/seat pin manual;

https://eu.ritcheylogic.com/eu_en/magb1/download/index/type/catalog_category/id/4/

the section on 'special characteristics of carbon' is interesting

cheers

"Special Characteristics of Carbon
As is the case with all RITCHEY products made from carbon composites, (b) special care and attention is required" (their capitalisation not mine)
Do I detect a bit of materials scientist mischief, Brucey? How is a saddles and seat posts manual relevant to a frame thread?
CF can be designed into 80% of the 2010 Sesto Elemento car. (link) Why Sesto Elemento? Carbon is the sixth atomic element and might be in production in next year's Aventador CF con rods saving 40-50% over steel con rods. CF is tremendously versatile with umpteen matrix variations available to the designer as you'll well know to withstand a massive range of temperatures, forces, etc. Why would bicycle designers and riders be indifferent to the attraction of CF?
Regards
tim-b
~~~~¯\(ツ)/¯~~~~

Ontherivet77
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Re: Yet another reason to avoid carbon frames

Postby Ontherivet77 » 11 Sep 2020, 9:36am

Here's a relevant article from cycling weekly:

https://www.cyclingweekly.com/news/late ... ife-277989

The head of engineering from Focus bikes seems pretty confident of the performance their carbon offerings, which is reassuring after reading some of the comments on this thread. Looks like I will be able to go for a ride on my 11 year old Focus Cayo next week after all.

bgnukem
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Re: Yet another reason to avoid carbon frames

Postby bgnukem » 11 Sep 2020, 11:57am

tim-b wrote:Hi

Do I detect a bit of materials scientist mischief, Brucey? How is a saddles and seat posts manual relevant to a frame thread?


A seatpost is a tube under stress, rather like a frame tube.

bgnukem
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Re: Yet another reason to avoid carbon frames

Postby bgnukem » 11 Sep 2020, 12:03pm

Brucey wrote:ritchey saddle/seat pin manual;

https://eu.ritcheylogic.com/eu_en/magb1/download/index/type/catalog_category/id/4/

the section on 'special characteristics of carbon' is interesting

cheers


Interesting they say 'don't leave in the sun'. I'm thinking of the thousands of carbon hired road bikes in places like Majorca and Lanzarote sitting outside cafes/hotels in the blazing sun! I suppose the hire fleets don't run their bikes for very long though.

I always thought the need to avoid grease was that it might attack the resin in some way, didn't think about the effect of absorption on friction though.

The lack of damage tolerance would bother me, the idea that a small scratch or abrasion could compromise the structural integrity.

Considering how some people treat their bikes, even quite expensive road bikes, bashing them around against other bikes and bike racks, I can understand why manufacturers would want to read the riot act, particularly given USA product liability and the compensation culture....

Brucey
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Re: Yet another reason to avoid carbon frames

Postby Brucey » 11 Sep 2020, 2:15pm

Ontherivet77 wrote:Here's a relevant article from cycling weekly:

https://www.cyclingweekly.com/news/late ... ife-277989

The head of engineering from Focus bikes seems pretty confident of the performance their carbon offerings, which is reassuring....


apologies if this seems b-obvious but would he be likely to say anything else....?

Of course not.

cheers
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