Bike handling

Discussion in 'Road Cycling' started by cyclintom, Oct 24, 2018.

  1. cyclintom

    cyclintom Well-Known Member

    Joined:
    Jan 15, 2011
    Messages:
    1,128
    Likes Received:
    83
    Because in order to have a "light" steel bike you have to make the steel tubing lighter than the end of that endurance limit. Likewise the aluminum frames are constructed with material heavy enough that they never reach their stress limits. Early titanium bike were also built too lightly and would fail. It was common for the Colnago Bititan with dual downtubes to break the welds of the downtubes or break the tubes year the welds because of stress multiplied by leverage.

    This is all engineering 101 so why are you questioning it? I used to see Reynolds 531 frames come in relatively often with tubes with crystalline fractures around the lugs. I didn't see one case of Columbus SLX frames breaking because they were heavier gauge tubing. Likewise you can find really high stress levels breaking anything


    In this you can see every material break. Does that mean that all materials are inappropriate for bicycle design or that the material has to have the proper design for the expected stress and material properties?
    View: https://www.youtube.com/watch?v=QoV2yliPmK4
     
    #81 cyclintom, Nov 26, 2018
    Last edited: Nov 26, 2018


  2. Froze

    Froze Well-Known Member

    Joined:
    Jul 13, 2004
    Messages:
    4,240
    Likes Received:
    282
    TOM, WAKE UP and COMPREHEND, you DON'T have a CLUE about engineering which several of us forum members have proven time and time again because of your complete lack of knowledge and understanding of simple stuff, so I wouldn't be so snarky if I were you towards others here.

    And Reynolds never had the issues you speak up except on rare occasions just as did ALL other steel tube manufacturers including Columbus because I saw those break...BUT I never saw a Reynolds break either, so what does that prove? It proves that you and I never saw thousands of frames from all the tubing manufacturers that ever existed; and this had nothing to do with Reynolds but had everything to do with the builder applying to much heat in the brazing process. I've gone over that before with you.

    Brazing is like glue, it holds the pieces together, silver brazing has a lower brazing temperature than brass has, and when builders first started to work with brass instead of silver because it was cheaper they overheated the tubing at the lugs to high of a temperature which would lead to fracturing; and I explained that to you before, but due to your lack of engineering knowledge you obviously didn't understand that or otherwise we wouldn't be having this discussion again.

    I have a Trek 660 with 531cs tubing that was brazed with brass and done so by robots, and after over 160,000 miles later there are no issues with frame weakness...but then again no bike I have ever owned ever suffered from that EXCEPT for a Ridley Scandium bike I had where the headtube cracked at the top which Ridley denied the warranty due to fatigue after just 8,000 miles!

    And again you are wrong about Reynolds being lighter than Columbus and that's why it failed, because Columbus actually had LIGHTER tubing then Reynolds had their 531 tubing thicknesses between 0.5 to 0.8mm Columbus with the Spirit tubing got it down to .38...yet Ishiwata had it down to .22! Neither of those steels if built correctly by the builder ever had issues with fracturing.

    And since you have a huge engineer brain read this: http://www.thetallcyclist.com/2016/09/theoretical-framebuilding-part-3-metals-heat/ If you can't understand what your reading, which about 99% of the time you can't even understand what others are saying on this forum not alone more complicated stuff like the above site, then I suggest you find someone who can read it to you in simple terms.
     
  3. dabac

    dabac Well-Known Member

    Joined:
    Sep 16, 2003
    Messages:
    2,125
    Likes Received:
    107
    I'm questioning how you can say that steel has the worst fatigue properties.

    Seems like you're intent on mixing materials properties with design properties, using characteristics of a marginal design as "proof" of your opinion about a material property.

    I'm done with this thread. I'm not going to become the cartoon guy.
     
  4. Froze

    Froze Well-Known Member

    Joined:
    Jul 13, 2004
    Messages:
    4,240
    Likes Received:
    282
    Wait don't go, you're discussing engineering principles with one of the foremost engineers of our time.
     
  5. cyclintom

    cyclintom Well-Known Member

    Joined:
    Jan 15, 2011
    Messages:
    1,128
    Likes Received:
    83
    Oh wait, froze wants to tell us that bikes are all correctly designed and take engineering into account for endurance limits regardless of the materials because his Trek was designed by the space shuttle design crew.
     
  6. Froze

    Froze Well-Known Member

    Joined:
    Jul 13, 2004
    Messages:
    4,240
    Likes Received:
    282
    Oh please tommy boy PLEEEEEESEEEEE show me where I said my bike was designed by the space shuttle design crew, I'm dying to see where I posted that. I know one thing for sure, I am extremely grateful my bikes weren't designed by Tommy boy! I would have been killed by a tragic frame failure if Tommy boy had done the design work.
     
  7. cyclintom

    cyclintom Well-Known Member

    Joined:
    Jan 15, 2011
    Messages:
    1,128
    Likes Received:
    83
    I don't know what you ever did for a living since the only thing you talked about is being a landlord. You and I have disagreed about a number of things, most especially helmets and your absolute belief in the safety increase from using a helmet.

    Be that as it may, I'm an engineer and have been for over 40 years. While not a mechanical engineer you have to have a good working knowledge of it for the research and development work I've done.

    If you look in Wikipedia you'd find this under Fatigue Limit: "The concept of endurance limit was introduced in 1870 by August Wöhler. However, recent research suggests that endurance limits do not exist for metallic materials, that if enough stress cycles are performed, even the smallest stress will eventually produce fatigue failure.

    For polymeric materials, the fatigue limit has been shown to reflect the intrinsic strength of the covalent bonds in polymer chains that must be ruptured in order to extend a crack. So long as other thermo-chemical processes do not break the polymer chain (i.e. ageing or ozone attack), a polymer may operate indefinitely without crack growth when loads are kept below the intrinsic strength.

    The concept of fatigue limit, and thus standards based on a fatigue limit such as ISO 281:2007 rolling bearing lifetime prediction, remains controversial, at least in the US."

    I am not saying this - the engineering manuals are.

    In short, contrary to most experience, steel has the lowest fatigue limit while carbon fiber is unlimited under certain conditions.

    The REASON that this seem contrary is because this assumes that the total strength limits of the material are not exceeded. 100 years of experience with steel frames gives them the advantage of knowing what their material will take. Aluminum and carbon fiber are fairly new and were used to reduce weight and their limits were not really known by the lower engineering experience of the modern generation of bicycle builders. Hence they have much less experience with the fatigue limits and they were passed all of the time. Also until recently they didn't use the appropriate polymer to hold the carbon fiber into a structural component.
     
  8. king bily

    king bily New Member

    Joined:
    Jan 16, 2019
    Messages:
    18
    Likes Received:
    2
    Tell that to Sean Kelly. He won classics out the yin yang and the Vuelta France on early Vitus aluminum frames...and multiple stages (5) with his powerful sprint. He won the green jersey FIVE times!

    The soft aluminium Duralinox fork was no detriment either. The glued together frame proves, once again, you're clueless.

    ALAN not only had considerable success with the glued and screwed aluminum frames starting around 1972. They went to pioneer carbon fiber construction with great success. Jeezus! So stupid it hurts
     
    brushyourideas likes this.
  9. cyclintom

    cyclintom Well-Known Member

    Joined:
    Jan 15, 2011
    Messages:
    1,128
    Likes Received:
    83
    You really should work on that reading comprehension.
     
Loading...
Loading...