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  1. #1
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    sapim CX-ray spokes

    So before I purchase these AMC sprint 350's, I have to know the advantages of the sapim spokes. Are they lighter and stiffer? Just wondering before I spend an extra $100 for something thats not worth it.

    Thanks

    -Scott

  2. #2
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    $100?!

    Quote Originally Posted by hambinator
    Just wondering before I spend an extra $100 for something thats not worth it.
    They are highly respected spokes, light and strong. However, an extra $100 sounds like an out-and-out ripoff.

  3. #3
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    Quote Originally Posted by hambinator
    So before I purchase these AMC sprint 350's, I have to know the advantages of the sapim spokes. Are they lighter and stiffer? Just wondering before I spend an extra $100 for something thats not worth it.

    Thanks

    -Scott
    CX-rays are like oval Revolutions. The oval shape makes them quite aero which gives them their main advantage.

  4. #4
    FTF
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    Quote Originally Posted by Nessism
    CX-rays are like oval Revolutions. The oval shape makes them quite aero which gives them their main advantage.
    Yes, they also hold tension better, they won't stretch as much as rev's. Once you get the rev's a to a certian tension, they will just start stretching, instead of putting higher tension on the rim. Sapim spokes are expensive though, very expensive, esp. in america. They are all made overseas, about 3 bux a spoke for the black ones if I remeber correctly, so it might well cost 100 dollars more to lace them with cx-ray's. DT rev's are a dollar a peice.

    28+32=60X$1=60bux for the rev's

    28+32=60X$3=180bux-60bux for the rev's=$120 for the sapim.

    Their spoke cost I'm sure is lower, but it dosen't seem like they are ripping you off any more than sapim is ripping everyone off.
    Last edited by FTF; 11-30-2005 at 06:30 PM.

  5. #5
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    Quote Originally Posted by Kerry Irons
    They are highly respected spokes, light and strong. However, an extra $100 sounds like an out-and-out ripoff.
    At my cost the cx-rays cost over $100 do build a pair of 28/32 hole wheels and Sapim does not give you a break if you are buying large quantities.

  6. #6
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    Quote Originally Posted by hambinator
    So before I purchase these AMC sprint 350's, I have to know the advantages of the sapim spokes. Are they lighter and stiffer? Just wondering before I spend an extra $100 for something thats not worth it.

    Thanks

    -Scott
    Cx-rays are the strongest lightweight spoke made. It starts out as the same gauge as a Dt revo then it is forged into a bladed shape which increase the strength and fatigue resistance.

    They are not any lighter then Dt revos though.

  7. #7
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    Quote Originally Posted by FTF
    Yes, they also hold tension better, they won't stretch as much as rev's. Once you get the rev's a to a certian tension, they will just start stretching, instead of putting higher tension on the rim.
    This just isn't true, at least not unless you've put so much tension on the spoke that you'll rip it apart. For the metal used in a spoke, it will not just keep stretching without increasing tension, unless you're close to the ultimate strength of the spoke. At these tensions, the material would be permanently deformed, and spokes just don't have this much tension -- the rim would fail well before you could put this much tension on a quality spoke.

    There's a good stress-strain diagram here: http://www.shodor.org/~jingersoll/we...ial/node4.html

    As for how much a spoke will stretch while you're riding, that will be in the elastic region of the steel. The steels used in spokes don't differ much in their stiffness (Young's modulus), so what determines how much a spoke stretches for a given force is the cross-sectional area (and length, but I'm assuming that's not a variable for the purpose here). In short, spoke stiffness is determined by cross-sectional area, and since the CX-Ray and DT Revos have the same cross-sectional area, they have the same stiffness.

    It's probably true that the cold-working of the CX-Ray results in a higher strength (not stiffness), but a spoke in a well-built wheel won't exit the elastic region so this doesn't matter.

    To the OP:
    I think there have been a number of discussions about the relationship of number of spokes and/or spoke type and wheel stiffness, and it's been concluded that for vertical stiffness, the tire has orders of magnitude more flex than the rim, so however you build the wheel won't really affect it.

    When it comes to lateral stiffness, the spoke thickness matters, but not as much as other factors, like rim selection and spoke count.
    There's data from actual tests here (gotta love Sheldon's bike archive):
    http://www.sheldonbrown.com/rinard/wheel/
    He says that on two otherwise identical 32 spoke wheels, one with the 2.0mm straight-gauge spokes is 11% stiffer than one with 2.0-1.45-2.0mm spokes, even though the spokes themselves are twice as stiff. (The cross-sectional area of a 2.0mm spoke is twice that of a 1.45mm spoke.)


    Anyway... I personally would get some AE15 spokes from Oddsandendos. Mike Garcia wrote a VERY good analysis of CX-Rays and AE15s here:
    Thoughts on Sapim CX-Ray vs. WS AE15/XE14
    Just remember: stiffness and strength are two completely different properties! If you want to know more about metallurgical properties, this is a good guide:
    http://www.strongframes.com/tech_gee...D=54&copyID=16

    Sorry for all the reading assignments... but you'll understand the issues much better if you read them.

  8. #8
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    I have the Cxrays on two wheelsets.

    Quote Originally Posted by hambinator
    So before I purchase these AMC sprint 350's, I have to know the advantages of the sapim spokes. Are they lighter and stiffer? Just wondering before I spend an extra $100 for something thats not worth it.

    Thanks

    -Scott
    The are on my Rolf Prima Elan Aero wheelset that now has over 8,000 miles on them without ever needing to be trued. I can't say the same for wheels that I have had with DT Revolutions.

    The other wheelset I have them on are still very true I just don't have that kind of mileage on them although I do expect the same type of performance from them.
    For my next trick I will now set myself on fire!

  9. #9
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    Quote Originally Posted by winstonc
    This just isn't true, at least not unless you've put so much tension on the spoke that you'll rip it apart. For the metal used in a spoke, it will not just keep stretching without increasing tension, unless you're close to the ultimate strength of the spoke. At these tensions, the material would be permanently deformed, and spokes just don't have this much tension -- the rim would fail well before you could put this much tension on a quality spoke.

    There's a good stress-strain diagram here: http://www.shodor.org/~jingersoll/we...ial/node4.html

    As for how much a spoke will stretch while you're riding, that will be in the elastic region of the steel. The steels used in spokes don't differ much in their stiffness (Young's modulus), so what determines how much a spoke stretches for a given force is the cross-sectional area (and length, but I'm assuming that's not a variable for the purpose here). In short, spoke stiffness is determined by cross-sectional area, and since the CX-Ray and DT Revos have the same cross-sectional area, they have the same stiffness.

    It's probably true that the cold-working of the CX-Ray results in a higher strength (not stiffness), but a spoke in a well-built wheel won't exit the elastic region so this doesn't matter.

    To the OP:
    I think there have been a number of discussions about the relationship of number of spokes and/or spoke type and wheel stiffness, and it's been concluded that for vertical stiffness, the tire has orders of magnitude more flex than the rim, so however you build the wheel won't really affect it.

    When it comes to lateral stiffness, the spoke thickness matters, but not as much as other factors, like rim selection and spoke count.
    There's data from actual tests here (gotta love Sheldon's bike archive):
    http://www.sheldonbrown.com/rinard/wheel/
    He says that on two otherwise identical 32 spoke wheels, one with the 2.0mm straight-gauge spokes is 11% stiffer than one with 2.0-1.45-2.0mm spokes, even though the spokes themselves are twice as stiff. (The cross-sectional area of a 2.0mm spoke is twice that of a 1.45mm spoke.)


    Anyway... I personally would get some AE15 spokes from Oddsandendos. Mike Garcia wrote a VERY good analysis of CX-Rays and AE15s here:
    Thoughts on Sapim CX-Ray vs. WS AE15/XE14
    Just remember: stiffness and strength are two completely different properties! If you want to know more about metallurgical properties, this is a good guide:
    http://www.strongframes.com/tech_gee...D=54&copyID=16

    Sorry for all the reading assignments... but you'll understand the issues much better if you read them.

    I agree with everything you just said but did not want to take the time to type that much out. One thing though the cx-rays are stiffer you can even feel it if you try to bend one with your hand compared to a Dt revo or Sa[im laser which is the same gauge as the Dt revo.

  10. #10
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    Quote Originally Posted by Juanmoretime
    The are on my Rolf Prima Elan Aero wheelset that now has over 8,000 miles on them without ever needing to be trued. I can't say the same for wheels that I have had with DT Revolutions.

    The other wheelset I have them on are still very true I just don't have that kind of mileage on them although I do expect the same type of performance from them.
    You probably can attribute the true to the rim, which is very strong and stiff, more than you can to the spokes.

  11. #11
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    On one of my early wheelbuilding efforts (quite a few years ago now) I over tensioned the spokes; stress exceeded the yield point causing plastic deformation in some of the spokes. This was with 15/16 spokes so I have no doubt that this same thing can happen with other spokes, particularly those that are thinner still.

  12. #12
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    Quote Originally Posted by Nessism
    On one of my early wheelbuilding efforts (quite a few years ago now) I over tensioned the spokes; stress exceeded the yield point causing plastic deformation in some of the spokes. This was with 15/16 spokes so I have no doubt that this same thing can happen with other spokes, particularly those that are thinner still.

    From what I've read (the endless debates with Jobst Brandt and others in newsgroups), spokes today are much better made than they used to be, and now rim strength is the limiting factor for spoke tension. I haven't been building wheels for that long, but the part about modern spokes matches with my experience -- I've built a number of wheels with DT revolutions and Wheelsmith AE15 spokes, and even when I tension the spokes high enough so that the rim starts to taco, the spokes are not plastically deformed. One of these days I'll get a tensiometer...

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