What is meant by a wheel being compliant?

Discussion in 'Cycling Equipment' started by 9202, Nov 23, 2007.

  1. 9202

    9202 New Member

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    What is meant when people on the forum say a wheel is compliant?

    The usage has me a bit baffled. I always believed that if a wheel reacts to even the slightest movement of the rider through the bars, then it is compliant, same with a frame or bike.

    Not sure I am correct as I have seen this term used but don't really underdstand the context. Can someone explain?

    Thanks
    Joe
     
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  2. bicycledisciple

    bicycledisciple New Member

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    Compliance, I believe, means deflection in a plane.
     
  3. bicycledisciple

    bicycledisciple New Member

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    Yes, you're right they talk a lot about it in marketing. A funny thing I encountered is that people talk about vertical compliance at the headtube, but among good quality bicycles today, the double diamond truss is inherently a pretty stable that it has quite high vertical compliance at the headtube anyway. So why make a big propoganda on compliance? Just marketing strategies ...
     
  4. sogood

    sogood New Member

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    Compliant in the vertical direction, and the ability to take up road surface irregularities and jarring. A deep rim would typically be less compliant in the vertical direction than a box cross section lightweight climbing rim.
     
  5. bicycledisciple

    bicycledisciple New Member

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    Do you have sources for this information?
     
  6. alienator

    alienator Well-Known Member

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    Compliant is a marketing term thrown around about wheels and a term used by people that don't understand wheels. All wheels pretty much deflect only parts of a millimeter in plane. Depth of rim makes very little difference. If you want compliance, reduce the pressure in your tires.

    There can be a difference in wheels in how energy is dissipated, but it's not something you can determine by type of wheel or just by looking at wheels.

    FWIW, comparing the ride of my traditional wheels (low profile alloy rims, CX-Rays, 24 2x front, 28r 3x DS, 2x NDS) to Reynolds Stratus DV's (46mm CF frims) and LEW VT-1 wheels (46mm CF/boron rims, CF/boron spokes), there is really sod all difference between them.
     
  7. bicycledisciple

    bicycledisciple New Member

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    sod all difference? you mean no difference at all? wow..
     
  8. alienator

    alienator Well-Known Member

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    Well, if all wheels deflect only parts of a millimeter in plane, and that deflection is much less than the deflection of the tire, exactly how well do you think you'd detect some such difference. If one wheel deflects 200 microns more than another, do you think you'll notice that?
     
  9. sogood

    sogood New Member

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    I think we've had a similar discussion not so long ago. Irrespective of whether you can measure it, or what physical lab parameter you measure, there's definitely a difference in feel of the ride b/n wheels of different depth.
     
  10. alienator

    alienator Well-Known Member

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    It's so good that science can just be thrown out like that, all because of what someone feels with their ass. That must be why there is still a Flat Earth Society.

    Well, since things are so easily determined and differentiated, now, we can fire all the scientists and let everyone's ass tell them what's going on. We'll just have to ignore, to maintain the illusion, that humans are wildly inaccurate sensors and that those "human sensors" are readily corrupted by emotional bias.

    But heck, if people done said they'd feeled it, it must be true......'cuz, well, they said it.
     
  11. sogood

    sogood New Member

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    If you can say that a 50mm deep rim gives the same ride feel as a 25mm box rim, then I pass.
     
  12. bicycledisciple

    bicycledisciple New Member

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    You may be pertaining to aerodynamics that can shave off a few seconds. Aerodynamics is just one of the factors affecting performance, there's stiffness, weight, strength and durability, and efficiency of braking surface.

    However, I don't know what you mean by ride feel. Thats not a technical term. Please elaborate.
     
  13. sogood

    sogood New Member

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    Aerodynamic features doesn't give you a difference in feel of the ride when going over rough surfaces.
     
  14. alienator

    alienator Well-Known Member

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    Well considering that your passing because your assumptions about behavior are based on nothing factual, then so be it. In fact, you cannot name a single reason why a deep section rim would have to ride more harshly than a low section rim. In fact, you have no data to support your claim. All you have is the typical internet mythology building toolbox, which in this case, is devoid of anything that actually leads to useful knowledge. In fact, it is such "assumptions" that lead to the stupid assumptions that people make about frame materials, MOI of rotating bicycle parts, and etc.

    Having an open, critically thinking mind would be helpful for you in this case.
     
  15. sogood

    sogood New Member

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    That observation is commonly noted. I am not aware of anyone who has stated that a deep rim wheel has a more cushioned ride than a box rim wheel (given identical tyre/pressure).

    As for finding a physical and measureable parameter. Well, round wheels were used and known to be better than square wheels for a long time before scientists were able to come up with all the physical parameters to explain it. In this case, I don't know if it has anything to do with the rim deflection, the rate of deflection, the deflection characteristics, a combination of these, resonance, or some other. All the data presented to date relates to min and max displacement with no description on all others.
     
  16. alienator

    alienator Well-Known Member

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    I have data at home, which I'll dig up, which shows quantitatively that with the same energy input to a deep CF rim and to a traditional box section rim, the resulting force acting on the forks is less for the CF rim than for the box section rim. In fact, that is the case for three different energy levels. Compared to another low section rim, the CF rim also had a lower resultant force on the forks than the low section rim.

    Of course, results are pointless because people will argue about how they must not reflect real world conditions. After all, what they think they felt was different.

    Actually, I think it's pointless in proving anything empirically to cyclists, because the vast majority have no interest in understanding how things actually work and behave. Nope. The vast majority are quite content with their assumptions based on what they feel or on whatever myth they've taken a fancy to.
     
  17. bicycledisciple

    bicycledisciple New Member

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    Why should we believe some "data" that you'll "dig" up from somewhere. Please point to authoritative sources.
     
  18. alienator

    alienator Well-Known Member

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    Ohhhhhhh, you're a feisty one, Girlfriend. I could really care less whether you believe the output from an accelerometer or not. I don't consider you a knowledgeable source for anything. Really, I could care less of Sogood believes the data either.

    Are we supposed to believe the "data" you provide in your blog, eh? Did you do an error analysis of your test setup? Did you provide an uncertainty with each result? Experimental results without an uncertainty would be viewed with a lot of suspicion by the engineering and scientific communities. That you didn't show an uncertainty or provide an error analysis demonstrates that either you didn't understand what you were you doing, you don't understand scientific method, or both.
     
  19. ScienceIsCool

    ScienceIsCool New Member

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    You have data now? Awesome! I'd love to see your accelerometer results. My hypothesis is that the variation between wheels is within the noise...

    John Swanson
    www.bikephysics.com
     
  20. Biker Joe

    Biker Joe New Member

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    My hypothesis is that the signal to noise ratio on this forum is way out of control.

    Alienator and John Swanson are a breath of fresh air. Why all the argumentative BS? Why do so many folks have such a problem understanding rational analysis or exprimental testing? It's not that hard folks.
     
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