Carbon frame question

Discussion in 'Road Cycling' started by VitaminE, Aug 1, 2003.

  1. VitaminE

    VitaminE New Member

    Joined:
    Jul 27, 2003
    Messages:
    8
    Likes Received:
    0
    Hello,
    I been thinking about a Trek 5200 but have been doing some research on carbon frames and am of the understanding that they do not last. As evidence. . .

    Carbon Fiber

    Pro: Light, strong, and easily tailored to achieve desired strength/stiffness properties.

    Con: Despite theoretical structural possibilities and advantages, carbon fiber frames do not have an enviable record of reliability, and one continuing problem are the joints and connections.

    There is evidence suggesting that long-term exposure to UV rays is damaging to the resins that bond carbon fiber. Failures tend to be sudden, and on-the-trip repairs are practically impossible.

    © Rivendell Bicycle Works 2000

    and. . .

    Carbon fiber frames have a short life span, but are great for long road riding (biathalons, triathalons). Carbon is not recommended for off-road bicycle frames.

    These two exerpts are taken fro different websites. Is this true? I don't want to spend a wad of cash and not have the frame last. Thanks. . .
     
    Tags:


  2. never_doped

    never_doped Banned

    Joined:
    Jul 30, 2003
    Messages:
    102
    Likes Received:
    0
    That little dump that Lance had ruined his frame and would probably not be covered by warranty.

    The best frame you'll ever ride is a custom built steel frame made by an experienced frame builder.

    Look for someone local that has been around for a while.
     
  3. oneradtec

    oneradtec New Member

    Joined:
    Jul 26, 2003
    Messages:
    185
    Likes Received:
    0
    Yes those steel frames are great..and built to last! I have a Moser and a Ciocc. For the money..I'm not sure there is a better frame out there that Cannondale's Optimo. I saw one in the shop today and I am very impressed. Well built, extremely light and strong with exotically shaped tubes..and beautiful paint and decals. This is a hard core racing frame!!!!! This is what Gilberto Simoni rode in the giro.


     
  4. BeeCharmer

    BeeCharmer New Member

    Joined:
    Nov 9, 2002
    Messages:
    3
    Likes Received:
    0
    Carbon fiber bikes are fine. The Trek OCLV is a tried and true design and mine has been fantastic and held up well despite 5000 miles carrying my 220lb carcass and meeting a light pole at 30mph in a crit last May.

    It rides through corners like it's on a rail and absorbs road noise better than steel or aluminum bikes, IMHO.

    Check out www.chainreactionbicycles.com for some good stories about OCLVs.

    chris
    ne iowa
     
  5. leona

    leona New Member

    Joined:
    Aug 3, 2003
    Messages:
    20
    Likes Received:
    0
    I've ridden many - a - road frame in the past. (I had a bad habbit of getting a new bike every year) In 2000 (when I was still a triathlete) I had a Trek 5500. I loved it UNTILL the second season. I did one IM in it and it went flat. The quick agility and perkiness that I had loved about it was gone, and appearently, others that I have spoken to had a similar expierence. I have since gone back to alluminum, and currently ride a Columbus E5 frame and love it.
    my $0.02.
    Hope it helps :)
     
  6. TT Cyclist

    TT Cyclist New Member

    Joined:
    Aug 3, 2003
    Messages:
    1
    Likes Received:
    0
    Been cycling for lots of years and rode everything. (I think)? Anyway, I think all materials steel, ti, carbon loose a certain amount of there properties after awhile. Just got done riding a Votex for the last 4 years. Sold it. Loss of stiffness, had a Colnago steel Masters 3 years loss stiffness. Now I'm riding a 5500 Trek and I would think in 3 years this frame won't be any different. After 3 years i'm tired of riding the same frame anyway.
    So buy what you like because nothing last forever and most likely you'll get tired of it after a few years and move on to another ride.
    Just my experience...
     
  7. BigT

    BigT New Member

    Joined:
    Aug 8, 2003
    Messages:
    2
    Likes Received:
    0
    This is a joke... there is a misconception that carbon will go "soft" after a while. This is NOT true. How can a frame material loose it's origional properties with usage? I agree that the joints can fail, but if manufactured correctly I don't see any problems.

    Based on any materials elongation numbers, a bikes tubes will break before going "soft"!

    I have been riding a Look KG96 Carbon/Kevlar since 1993. I raced with it for 5 years and have logged AT LEAST 100 000KM on the bike! I can honestly tell you that the bike feels exactly the same as the first ride. I am really glad Look gave me this frame in my racing days!

    BIGT
     
  8. tafi

    tafi Member

    Joined:
    Jul 31, 2003
    Messages:
    1,038
    Likes Received:
    17
    Mate, ya just don't get it do ya?
    Aluminium is THE prime example of a material that DOES NOT LAST!
    As a mechanical engineer I have studied the material properties of many materials. Aluminium has the advantages of light weight and stiffness (if alloyed correctly). But its primary disadvantage is that ALL aluminium components will eventually fail through fracture.
    Many people will be able to tell you about aluminium frames that go soft over time and eventually cracks form and its time for a new one!
    Why else would a pro who rides Al frames be given up to three race bikes at different times during the euro season?
    Why else would a warranty be voided if the frame is used on a stationary trainer?
    Because aluminium ALWAYS fatigues and fails, thats why!

    Steel frames on the other hand CAN be constructed to last forever. Whether or not they actually are is another story.

    Carbon is an unknown quantity and depends on who makes it and how.
     
  9. patch70

    patch70 New Member

    Joined:
    Jun 19, 2003
    Messages:
    1,682
    Likes Received:
    0
    I wouldn't hesitate to go for carbon. A good carbon bike will last a long time; Trek would not give lifetime warranties otherwise.

    It is impossible for carbon "to go soft"; it cannot occur. If you are worried about joins (which I believe is unfounded), go for a monocoque like the Bianchi XL Carbon which is a similar price to the Trek 5200/5500. I have one and absolutely love it.

    Yes, steel is also a great material but if it is too lightweight (eg ultrafoco) it will be broken without a huge amount of force in a crash. Ditto for very light aluminium. The main reason that the pros mainly use aluminium is that it is relatively cheaper and easier for the sponsors to provide them with at least 3 bikes a year in that material.

    If you want a bike to last, go for good quality carbon, steel or titanium but avoid the superlight bikes. I am not saying aluminium will not last but personally I prefer the feel of the others.
     
  10. tafi

    tafi Member

    Joined:
    Jul 31, 2003
    Messages:
    1,038
    Likes Received:
    17
    I would like to know the basis for the "impossibility" you outline above. The properties depend entirely on the maufacturer and it is impossible to compare material properties between frames.

    Carbon is also prone to breakage in a crash. The tubes do not yeild when squashed like Al or Steel but crush and splinter. Even if you only scratch away the resin, the fibres may be exposed, in which case the frame will be a dud. Steel and Al are more likely to spring back somewhat and actually remain structurally sound, even with a dent.

    Trek give a lifetime warranty on their Al frames as well and aluminium will always eventualy fail. The reason that Trek provide such a warranty is for marketing. Most riders are not prepared to hang on to their bikes for more than a couple of years if they race hard and so sell off their bikes before they have a chance to fail. The second hand buyer then has the liability on their hands and the warranty is not transferable. That is why companies like Trek are prepared to offer lifetime warranties because they can absorb the cost of a few anomalous owners who keep their bikes for a long time.

    As for steel, the difference in wall thicknesses between "standard" and "lightweight" steels is usually only about 0.02mm (eg: Foco and Genius has minimum thickness of 0.4mm and UltraFoco has min. thicknesses of about 0.38mm). The difference is almost academic and the reason Ultrafoco costs more is because more accuracy is required in butting so as not to cut too close on their factor of safety.
     
  11. patch70

    patch70 New Member

    Joined:
    Jun 19, 2003
    Messages:
    1,682
    Likes Received:
    0
    >"I would like to know the basis for the "impossibility" you outline above."
    The structural property of carbon fibre is such that the chemical bonds will not slip and make the material "soft". It just can't happen.

    Re: Ultrafoco. Have a look at an ultrafoco frame that has been in a crash. It looks about as thick and strong as aluminium foil (or 'tinfoil') used in cooking. The strength is reliant on maintaining the round shape of the tube and if it does dent you are taking a big risk if you assume the integrity is still there.

    No good racing frame is particularly ideal for crashing on and I would not give up on Carbon for how it copes with a crash.

    A bike store owner recently showed me two 15cm sections of tubing; one from a Trek 5500 and one from a Cannondale CAAD7. He jumped on the carbon tube and nothing happened. The aluminium crumpled easily. Sure there is more to bike durability than this but I am very comfortable, both physically and mentally, with carbon.
     
  12. tafi

    tafi Member

    Joined:
    Jul 31, 2003
    Messages:
    1,038
    Likes Received:
    17
    Carbon fibre is not bound chemicaly.
    It consists of carbon fibres (rather like human hairs only perhaps thiner) braided and then layed around a mould before they are set in a resin which holds the carbon in the proper position. The only chemical reaction that can occur is in the vulcanization of the plastic resin. The fibres are unreactive (unless you set them on fire!) and are simply kept preserved in the resin.

    The nature of plastic itself is that it is not bonded chemically, it exists as a mess of long chain hydrocarbons which do not fall apart because of entanglement of molecules.

    People who use carbon should be fairly au fait with the phenomenon of fibre pullout, where under repeated stress, the fibres, being finite in length, are pulled through the resin resulting in the material loosing integrity over time.

    I'm not trying to put you off what is obviously your conviction, but I have studied the properties of various materials, including carbon fibre and I feel it necessary to point out these things. Further to this, my brother works as a mechanic at the biggest Trek dealer in Australia and replacements of 5200 and 5500 frames seem to be constantly occuring in their workshop.
    I have also seen my brother's carbon fibre Look crack all the way along the chainstay when riding over a speedhump. It now hangs in his room.
     
  13. patch70

    patch70 New Member

    Joined:
    Jun 19, 2003
    Messages:
    1,682
    Likes Received:
    0
    And I (and probably most other cyclists) have seen plenty of people have problems with breakages in steel, aluminium and titanium frames...
     
  14. filtersweep

    filtersweep New Member

    Joined:
    Jul 11, 2003
    Messages:
    9
    Likes Received:
    0
    No kidding... when is the last time you saw an aluminum FORK? When is the last time you saw a new bike WITHOUT a carbon fork?
     
  15. bikerphil7

    bikerphil7 New Member

    Joined:
    Aug 16, 2003
    Messages:
    1
    Likes Received:
    0
    did you know some supercar exotics (eg ferrari etc) use carbon fibre as the frame tunnel in the chassis? many f1 cars are full carbon chassis (including rear suspension and disc brakes!) or integrated alum. carbon. obviously these cars handle very extreme tolerances. however these are also million dollar machines....i think (imho) that whomever said that it really depends on the manuf. and the way it has been designed ($$$)was "most correct" ...nothing lasts forever by any means
     
  16. BIANCHI_EURO

    BIANCHI_EURO New Member

    Joined:
    May 30, 2004
    Messages:
    124
    Likes Received:
    0
    I read the very interesting discussion and I have a few comments.

    There are two ways (by my knowledge) of manufacturing a carbon frame.

    1. Using tubes and glue them with epoxy resin into the lugs.
    2. The monocoque construction.

    Option 1 Has the weakness that due to vibrations the
    glued connection between lugs and tubes can crack. However you’ll see that those frames are available in centimetre measures. Option 2 has the disadvantage that it is not a real monocoque construction and those frames are only available in a few sizes.

    The so called monocoque construction means that the manufacturers use a mould. The carbon fibres are put into the mould, the resin is applied and in this way two half shells are created. Now the alu parts like bracket and reinforcements have to be mounted before the two shells are fixed together.

    Having quiet some experience with manufacturing all kinds of composite windsurf boards, I am quiet worried about the seam that exists between both shells. With all the vibrations of road racing I am afraid that this construction is prone to cracks along the seam of the frame. My condolances go to the Australian guy who lost his brother’s trek. It amazes me that the crack occurred in the chainstay?! I would assume a crack in the seam would be much more likely to happen.

    In the forum somebody writes that professional cyclists favour alu above carbon for frame material. Indeed most pro’s cycle on alu bikes. However the reason for this is probably a different one. At the start of the season the pro’s give their personal measures to a frame builder. He will make a custom fit frame for the cyclist. However with the monocoque construction the frame builder would have to order an incredibly expensive new mould specifically for the measures of just one pro. This is impossible and therefore probably the pro’s favour a well fitted alu frame above a not perfectly fitted carbon one.

    "If you have been to a bike shop lately you’ll have noticed that at once frame size doesn’t matter anymore for the new monocoque frames, right"? Well anyone can figure out now why. If a manufacturer orders a mould for every 3 centimeter sizes instead of one for every centimetre it will save him 2/3 of the cost for these expensive moulds. Of course size is for any bike just as important.

    Another important thing about carbon. If the carbon tubes break in an accident and if the fibres penetrate your skin/organs, unlike metal you can’t pull it back. Once I got a sharp broken carbon fibre in my finger and finally I had to push it all the way through my finger in order to pull it out on the other side of my finger. Carbon fibres are full of (what we in the Netherlands call) “weatherhooks”. When you pull they ‘ll cut into the flesh deeper. It worries me very much what would happen if you have a serious accident. Does anybody know about an accident like that?
     
Loading...
Loading...