Chainstay flex myth

Discussion in 'Observed Trials Discussion' started by afrobot, May 24, 2004.

  1. afrobot

    afrobot Aluminum is for recycling

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    It occurred to me in a moment of drunken clarity ,that this is a bullshit myth.If your chainstays flex,yes they do "bounce back".However ,energy is lost.Pedal kicks as well loose energy.
    Eh.
    Maybe it's more like a trampoline effect ,whereas it aplifies power.But I kinda doubt it.
    who cares..I just felt like starting a new topic.
     
  2. WhiteRavenKS

    WhiteRavenKS Well-Known Member

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    amplifies? what the duece are you talking about...

    hey lets make this a physics discusion!
     

  3. KeepRollin

    KeepRollin New Member

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    The only way you could get it to amplify is to bounce it at it's natural frequency. Good luck with that one!
     
  4. B1105

    B1105 New Member

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    ahh i took physics this year, force=mass times what?
     
  5. afrobot

    afrobot Aluminum is for recycling

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    Datz vat eye taught .Bullshizzle.
     
  6. Bloodhound

    Bloodhound Steffen L.T.

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    True, but you dont need to be perfectly on time. Something close will still amplify it, just less. I might be completely wrong but... Maybe thats why BIU riders ride more 'explosive', to time it better with the rear triangle's 'natural frequency'. I think stiffer is generally better, feels more lively/responsive and you get quicker, more effective power transfer.
    It would be interesting to hear from somebody who actually knows about wave physics and stuff.

    This is a useless post in a useless topic
     
  7. Andreas

    Andreas All About Trials

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    acceleration
     
  8. afrobot

    afrobot Aluminum is for recycling

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    I am a useless rider in a useful forum! :Wavey:
     
  9. kamil

    kamil Guest

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    <my understanding>

    resonance freq amplifies, and that's not very big, in order for it be on a scale large enough to actually be noticiable you would have to do it over and over at exactly the right frequency.. so you would be doing something like this: preload preload preload preload preload preload preload preload preload preload preload preload preload preload preload preload preload preload preload preload preload preload preload preload preload preload .... preload

    just think of constructive interference in waves, that is what you would have to do in order to actually be able to manipulate the chainstay flex and vibrations.


    untill it got to a point where the amplitude of the flex was enough to be noticed...

    </my understanding>

    who ever said it was a worthless post was right.
     
  10. AgrAde

    AgrAde From your head to your fists

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    of course its a myth. deng said it. stupidest thing i have ever heard. "hur hur we'll copy a frame that is designed completely around having a stiff rear end*... BUT WE'LL MAKE IT FLEXY AND SAY THAT FLEX IS GOOD!!!"**

    next on the zoo! frame list: a fully suspended 26" with 3 inches of completely undampened travel "IT MAKES YOU SPRING UP GUYS WOO"

    * my understanding anyway, please correct me if there is another reason for the miltiple tubes on the coustellier

    **deng is a fag
     
  11. TRA

    TRA this is very uninteresting

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    multiple tubes are for getting rid of the BB flex ,not mainly the chainstay flex, but it helps on the chainstay flex aswell because tubes on the side are have some angle rearwards..
     
  12. AndyT

    AndyT New Member

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  13. DangerousDave

    DangerousDave Active Member

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    Ok really it doens't fucking matter. Echo/Zoo riders can beat 99% of the riders on the board. so does it matter their rear end flexes? no

    I could gap far on the zoo and I can gap far on my megamo.

    Its like a difference in geometry. some ppl want a 1080 wheelbase some ppl want a 1081 wheelbase. if you want a flexy frame get a flexy frame.

    woohoo
     
  14. RomanC

    RomanC Well-Known Member

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    I think that a flexy chain stay can give you an advantage during sidehop. If you start from two wheels and then kick to rear/preload and go up. Its like a pogo stick effect, where the stays act as a spring in which you store energy prior to going up. I can usually sidehop with lower tire pressure compared to higher pressure. So I think a flexy rear end has its advantages and disadvatages.
     
  15. Ryden

    Ryden Guest

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    Wholy this spurred a lot more discussion than I thought it would.
     
  16. Trials_Phoenix

    Trials_Phoenix Guest

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    I've jus got one thing to say =P Who cares?
     
  17. RomanC

    RomanC Well-Known Member

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    I personally want to know as knowledge is power and increases our view of the world. I don't want to say that I am huge trials geek but I like to know why stuff works the way it does.
     
  18. DMArnt

    DMArnt Guest

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    I take it ur talking about vertical flex?
    Its myth. Remember the normally black, but can come in diff colours, round thing full of air thats between your chainstays? U know, that thing that flattens out when u preload and absorbs all that build up energy before u kick, hop etc? Its not ur frame.
    There is no way u could flex ur stays vertically. The frame would break before you had any flex to spring.
    Frames do flex sideways (at the BB), but even then I can't see how you can get xtra spring from that. It your tires storing/releasing the energy and the shifting of the bike and rider weight that gives u the lift, not ur frame.

    There is one way to test it though. Take ur wheels off, balance on the dropouts and try side hopping etc. This might be what Deng does in his quest to design the perfect frame.

    Fun.
     
  19. ascentrek

    ascentrek Original power yuppie

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    If it flex's back, you haven't lost energy, just temporarily stored it in the flex motion. Some dampening may occur (you'll loos engergy there).

    ...can we go back to drinkin'?