spoke tension for Mavic CXP 10?

Discussion in 'Cycling Equipment' started by dtaffe, Dec 1, 2006.

  1. dtaffe

    dtaffe New Member

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    I'm building a fixed gear wheel using a White Industries Eno Hub and a previously-used Mavic CXP 10 rim from an old wheelset. I have a Park tensionometer, but I can't find the recommended max spoke tension for this rim. Does anyone know the recommended tension, or can you point me to the information (I can't find it on the Mavic site.)?
    Thanks, Danny
     
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  2. alfeng

    alfeng Well-Known Member

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    23.5 for straight 14 gauge spokes is what I recall ... I think the information on recommended spoke tension is on the PARK site.
     
  3. fish156

    fish156 New Member

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    This is an easy one. Mavic recommends 90-110 kgF spoke tension on ALL of their rims. You can call them and have them tell you this or your can go on the "dealer only" tech support site and see for yourself. I have talked to Mavic reps, tech support, and race support people on many occasions and the answer is always the same.

    Max spoke tensions are based on what the rim manufacturer tells you, not what type and size the spokes are.
     
  4. alfeng

    alfeng Well-Known Member

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    I believe that 23.5 "reading" for a 14g straignt gauge spoke on the Park Tensiometer falls within the range you specified ... and, the user can extrapolate from that number OR use it as s/he sees fit.
     
  5. fish156

    fish156 New Member

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    Danny wanted to know what the max tension for that rim is. It's 110 kgF. What the reading on a Park TM-1 will be, to get 110 kgF, will depend on what spokes he is using. He did not say what spokes he will be using, so what the reading will be remains to be determined. Hopefully, since he's taking the time to build the wheel, he'll make a good decision and use double butted spokes, which are the best to use in most applications.
     
  6. dtaffe

    dtaffe New Member

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    Thanks for all the info. I'm using 14-15-14 double butted spokes. I have the chart to convert the tensionometer readings to actual spoke tension; I just couldn't find the rim-specific tension. I'll set them just shy of 110.
     
  7. alfeng

    alfeng Well-Known Member

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    You are correct, the spokes to be used were NOT originally specified ...

    And, while I know the conventional wisdom is that double-butted spokes build a stronger wheel, to me that notion has less credibility than an urban myth ... AND tales of Sasquatch sightings are more believable to me.

    I've read some of the logic, and it doesn't ring true.

    Don't get me wrong, back in the dark ages, when stainless steel spokes were just becoming available, I was keen to reduce the weight of one wheelset that I was going to lace up back around 1980, so I laced the drive side x4 with 14g spokes and the non-drive side x3 with 14-15-14 double butted spokes. YOU KNOW, the non-drive side is less tensioned than the drive-side on a most rear wheels ...

    I've even got some wheelsets which I've laced more recently that have double-butted spokes! :eek:

    The "new" wheel is going to have an ENO hub which I presume (perhaps, incorrectly) is for a fixie or single-speed ... essentially, an EQUALLY dished wheel ... so, both sides of the wheel will be sharing the load.

    Indulge me this soap-box moment ...

    Now, the advantage of a single gauge spoke is that it will build a laterally stiffer wheel -- you know, for handling in turns ... but, if YOU or anyone else wants to ride a wheel with more lateral deflection because s/he thinks that it is a stronger wheel build because (t)he(y) read it somewhere (where was that originally posited?), well I guess I have to say: to each his/her own.

    I guess a spoke laced with double-butted spokes is good for a townie or beach cruiser ...

    Shockingly, think about this for a moment, both Shimano & MAVIC (and, others!?!) only use single gauge spokes on their factory built wheels which have steel spokes. Why is that? The buyer is already paying a fair amount for the wheels AND another $10/(more!?!)-or-so isn't going to dissuade the buyer.

    Gotta believe that the engineers at those firms have ALSO deduced that straight gauge stainless steel spokes actually builds a stronger wheel than a double-butted stainless steel spokes rather than the matter being determined by the coroporate bean counters.

    If anyone wants to believe that a double-butted spoke results in a stronger wheel, then to each his/her own ...

    If I am a troglodyte for thinking that a straight gauge spoke results in a stronger build when conventional wisdom proclaims otherwise, well, I guess you'll have to pity me from your side of the fence.
     
  8. Retro Grouch

    Retro Grouch New Member

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    I think it's funny that a guy who's so in love with different fonts and colors would want his spokes to be uniform end-to-end.
     
  9. alfeng

    alfeng Well-Known Member

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    HA!

    Well, think about it ... based on YOUR observation, that should suggest to you that if I am willing to subordinate what you seem to presume would be my inclination toward showy spokes and/or spoking, then the STRAIGHT GAUGE spokes MAY BE BETTER ... FOR ONE REASON OR ANOTHER -- that is, functionality.

    BTW. Color added for emphasis ... in case you didn't know what its general function is.
     
  10. fish156

    fish156 New Member

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    While everybody has his or her own ideas about wheelbuilding, virtually every expert that I have ever studied agree on one thing, and that's double butted spokes make the best wheels - and, make no mistake, there are plenty of issues that these guys disagree on. The names include Sheldon Brown, Jobst Brandt, Gerd Schraner, and Peter White. This is no urban myth. It's right there in black and white in their books and websites for anyone to read.

    There are some specific applications for other types of spokes, but the overwhelming majority of builds call for DBs.

    But, I suppose if you know more about building wheels than the people in that list then, by all means, make your argument.
     
  11. fish156

    fish156 New Member

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    I have built many wheels using CXP10, CXP21, CXP22, CXP33, MA3, and OpenPro rim types and built them all using 110kgF as my target spoke tension. I can promise that you'll be happy using this figure. Good luck with your build.
     
  12. Retro Grouch

    Retro Grouch New Member

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    OK, so explain how you came to the conclusion that wheels built with straight gauge spokes are "stiffer". How did you factor out the hugely greater deflection of the pneumatic tire When you made this analysis?

    (Black and white retained because my writing is clear enough that it needs no additional emphasis.)
     
  13. alfeng

    alfeng Well-Known Member

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    I know it's hard for some people to believe, but Jobst Brandt isn't always right about wheel building ... in fact, I am quite certain that if he were to think about ONE comment he wrote which I recall was printed in Buycycling (as someone referred to it) several years ago, well, it was just so illogical that everything else necessarily comes into question. Brandt's contributions were so infrequently (one?) that it should be easy enough for one of you to find -- look for it ... think about it ... if you can agree with Brandts' analysis then keep drinking the Kool-Aid!

    Oh sure, Brandt has a Stanford engineering degree ...

    What if I said that I was at the commencement exercise a CalTech in 1969?!?

    Yeah ... you guessed it ...

    I was a visitor!

    Degrees don't matter ... you mentioned Peter White ... I don't know what degree(s) he has, but he does (rightly) disdain the notion of being DT Certified ... that is NOT to equate DT Certification with an engineering degree from Stanford, BTW.

    You do know that if you rummage around long enough, you will see that Sheldon Brown has some minor errors on his site -- undoubtedly, inevitable since there is so much information there.

    If I hadn't been lacing wheels for decades before reading what Sheldon Brown wrote, I am sure I might be inclined to embrace Brown's notion of wheel building, too!

    I suppose some might suggest that I might failure to embrace the urban myth of double butted spokes being better qualifies me as a Luddite!

    Straight gauge vs. double butted? Just grab a pair of crossed spokes on a wheel laced with straight gauge AND on one with double butted spokes (presuming the wheels are properly laced & tensioned, of course) ... give them a squeeze and see how much the respective rim deflects. The rim on the wheel laced with double butted spokes (all other things being equal) will deflect more. If that's what you want ... well, good for you!

    If you want to lace with double butted spokes, please do so ... DT, Sapin, Wheelsmith, and whomever are all the happier!

    Schraner ... did he originate the myth(s)?!?

    Now, Peter White undoubtedly builds a great set of wheels ... he knows what customers want & what works AND what he can guarantee; but, that doesn't necessarily mean that it is the best wheel he can build ...

    Nothing really to argue about, IMO ... you can choose DB spokes ... as noted, I have several sets of wheels which I've laced with double butted spokes (heck, as recently as this past Spring!), but if I were offering MY preference and recommendation, I would almost always recommend straight gauge spokes.

    BTW. You do know that GRAPE Kool-Aid doesn't provide any anti-oxidants, don't you?:)
     
  14. fish156

    fish156 New Member

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    So ...... you just dissed Sheldon Brown, Jobst Brandt, Gerd Schraner, and Peter White. Excellent!

    I guess there's no arguing with your logic. What a piece of work.
     
  15. alfeng

    alfeng Well-Known Member

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    To reiterate:

    Straight gauge vs. double butted? Just grab a pair of crossed spokes on a wheel laced with straight gauge AND on one with double butted spokes (presuming the wheels are properly laced & tensioned, of course) ... give them a squeeze and see how much the respective rim deflects. The rim on the wheel laced with double butted spokes (all other things being equal) will deflect more. If that's what you want ... well, good for you!

    Make your own empirical observations and draw your own conclusion(s).
     
  16. alfeng

    alfeng Well-Known Member

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    Hardly.

    Pointing out what I think is an error isn't dissing ALTHOUGH I suppose it is your intent to diss ME! :(

    BTW/FYI. Even Nobel Lauretes are disagreed with ... the recently deceased Milton Friedman comes to mind. :eek:

    Okay ...

    The fact that you apparently aren't literate enough (now, this IS a diss in case you are missing it) to understand what you are reading doesn't mean that everyone else is.

    To return to SOME civility:

    Calling the Sacred Cow of double butted spokes an "urban myth" doesn't mean that I am wrong ... nor, does it mean that I am right. Was the World flat until Magellan circumnavigated or was a Flat Earth an urban myth?

    If you prefer a softer wheel, then I can't argue with the choice of double butted spokes ...

    So, FWIW, I was/am just stating a preference based on MY observations rather than simply accepting what someone else has written.

    Worship at the feet of those whom/what you choose!

    It's a free country (for the time being) ...
     
  17. Retro Grouch

    Retro Grouch New Member

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    I guess that I don't understand what you are saying because I don't understand how that could possibly produce the result you are predicting.
     
  18. alfeng

    alfeng Well-Known Member

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    First, I suppose that it is better to "grab" a pair of spokes from adjacent crossed pairs; but, no matter.

    Second, you need TWO wheels which are identically laced except for the spoke types used.

    If you don't notice the rim deflecting from the central plane more easily with the wheel that was laced with double butted spokes, then perhaps I am dealing with a princess-and-the-pea-type observation ...

    Having been on a noodly wheel built by a local bike shop ONE TIME, I happen to know that a laterally stiff(er) wheel is more important to cornering than people who advocate using a double butted spoked wheel apparently can imagine ...

    Aufgabe Eins -- why a laterally stiffer wheel is better. A spinning wheel is a gyroscope, of sorts. A gyroscope tries to maintain its orientation. At the extreme, a laterally softer wheel will be able to more easily maintain its predetermined direction as it distorts the spokes, if ever so slightly, and thus be harder to turn to varying degrees as determined by the lateral flexibility of the wheel (amongst other factors) ...

    Having said that, I must repeat that I am NOT trying to convince anyone to stop using double butted spokes!
     
  19. Retro Grouch

    Retro Grouch New Member

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    I can certainly agree with that. Sometimes I think that I must be the only bike guy in the world who doesn't "get" the whole stiffness thing. Other times I think that I'm the only one who understands it.

    If you push down on a stack of coil springs, the weakest ones will always flex first. Your bike rides on pneumatic tires. They probably flex 10 times as much as everything else put together. I think that it's all-too-easy to overstate the effect of relatively tiny differences in other, much stiffer, components.
     
  20. ScienceIsCool

    ScienceIsCool New Member

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    Alfeng, if you have an argument to make and wish to counter the prevailing wisdom, you would do well to elucidate. As it is, I think you've confused two terms. Lateral stiffness and strength.

    The lateral stiffness of any wheel is defined by the following elements:

    - beam stiffness of the unsupported rim between spokes (second moment of inertia)
    - bending stiffness of each spoke (related directly to the second moment of inertia). For a round spoke, this is dependent on diameter. For aero spokes it's a bit more complicated.
    - number of spokes.
    - to a very tiny degree, wheel stiffness is affected by the number of spoke crossings. Empirically, the lateral stiffness is measured to go down with the number of spoke crossings. I.e., radial wheel is laterally stiffer than a 3x

    So it could very well be that the straight guage spoked wheel is laterally stiffer than a double butted spoked wheel. Then again, it might not. There's a few variables to consider.

    I would define the strength of a wheel is it's ability to handle riding conditions without breaking. Swaging a spoke (double butting) allows you to put more material is high stress zones such as the elbow and threads. It also allows you to take material away from the central portion where it is not needed. I could see how this would indeed make a stronger wheel.

    Lastly, the experts are often recognized as such for a reason. It's important to question any claim (it's a great way to learn and discover), but to stand in a public forum and say they are wrong... I'd suggest that you have a very clear argument why that would be the case.

    John Swanson
    www.bikephysics.com
     
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