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  1. #26
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    Did the mechs mention the tension at at which that crack started developing?
    I am immune to your disdain.

  2. #27
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    Quote Originally Posted by illnacord View Post
    deezee, where is the crack? Those red arrows aren't pointing to any?! You should see how my Enve's look after a couple seasons of use - just like that! The stickers look bad from all the contact they've made with twigs, brush, bushes, rocks, but the rims feel smooth on the surface. The lines are below the outer layer as in they cannot be felt.
    It happened when the LBS was lacing them.

    Just as a disclaimer I don't know for 100% sure if it was the rim or the wheel builder.

  3. #28
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    Quote Originally Posted by indyfab25 View Post
    DeeZee,
    Which rims were they? I've been looking at these...
    Wholesale 29er rim carbon rims down hill XC & AM racing
    How long ago was this? I am curious.
    No this is a different rim. It is wider and just a tad heavier.
    I have been eyeing these for a few weeks….may give them a try!

  4. #29
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    Quote Originally Posted by DeeZee View Post
    No this is a different rim. It is wider and just a tad heavier.
    I have been eyeing these for a few weeks….may give them a try!
    You are brave.

    I believe this is the rim we have for testing. We'll see how it goes. My expectations are low.
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  5. #30
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    Quote Originally Posted by DavidR1 View Post
    I don't build wheels, could you please explain "tow alignment" and how it is off on these rims?
    This is all I could find.
    Sheldon Brown's Bicycle Glossary M

    I would like to know as well.
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  6. #31
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    The cracked rim seemed to have a low spoke count? I'd always go for 32h, even if the rim is supposed to hold up with 16. If it's overkill, there's always lightweight (flexy) spokes.

  7. #32
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    Quote Originally Posted by Cloxxki View Post
    The cracked rim seemed to have a low spoke count? I'd always go for 32h, even if the rim is supposed to hold up with 16. If it's overkill, there's always lightweight (flexy) spokes.
    Nope 32 holes............

  8. #33
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    what this thread needs is additional data points

  9. #34
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    Sketchy.. Carbon Rims should be able to take a higher spoke tension no?
    beaver hunt

  10. #35
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    Quote Originally Posted by snowdrifter View Post
    Sketchy.. Carbon Rims should be able to take a higher spoke tension no?
    Much, much higher.
    The Carbon Wheel Experiment: Part V- Reynolds MT29 Wheels: On Test | Twenty Nine Inches
    According to Guitar Ted, Reynolds rims go from 950 – 1150 N.
    I'm picking up a set of these wheels. I'm forgoing the Chinese carbon. Not worth the risk.
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  11. #36
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    Quote Originally Posted by DeeZee View Post
    Not sure. My LBS stopped building them as soon as the crack became visable
    Although it's hard to say without seeing them in person that looks like a mold release line. The rim mold is in two halfs and they come together right down the center line of the rim. It often leads to a line or a slight ridge running right down the center of the spoke holes. It could be sanded off but cheaper manufactures won't bother. I've built close to a thousand carbon rimed wheels at this point and almost all of them have some kind of mold mark in that spot. It may well be a crack but I wouldn't throw them away until I got a second opinion.

  12. #37
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    I noticed this thread on weight weenies about chinese carbon rims/wheelsets.

    Weight Weenies • View topic - Carbon 29er rims

  13. #38
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    I went ahead and ordered a set of the wider rims from light-bicycle.com. should get them in a couple weeks. We'll see how they look
    A ride a day keeps the therapist away.

  14. #39
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    Ive been on my set for about 50-100miles now. Built them with AC hubs and Sapim CX-rays. Im 200-215lb and im not babying them. So far theyve been great! I have a set of AC XCs and a set of hope/stan 355s and these are easily my favorites. The ride quality is much better. They feel as stiff as anything else and theyre the lightest by quite a bit (very low 1500g range). If your on the fence about these I would say go for it!

    One thing I should mention is I had mine built with the "old" layup. Im told 390g rims are the new layup. Mine are 415g.

  15. #40
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    Quote Originally Posted by Jwiffle View Post
    I went ahead and ordered a set of the wider rims from light-bicycle.com. should get them in a couple weeks. We'll see how they look
    Hoping you (or someone else can answer my question) - Under Product options it lists the following:

    12K
    3K
    UD

    What is the difference between the 3? TIA!

  16. #41
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    3k, 12k, UD refer to the cosmetic final wrap of carbon. Core construction is likely the same no matter which you chose. 3K is a tighter weave pattern than 12k, UD is likely what they are built with (ie, no cosmetic wrap).

    Hope I understood your question correctly!

  17. #42
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    Quote Originally Posted by DavidR1 View Post
    I don't build wheels, could you please explain "tow alignment" and how it is off on these rims?
    I do build wheels (well, I've built about a dozen). And none of the sources I ever used when learning to build wheels (Brandt's book, Brown's site, fellow mechanics) ever mentioned "tow alignment."

    I believe what he is referring to is that he doesn't trust a "cheap" carbon wheel but didn't have any reason to not to, so made something up, seeing as the term is just made up. I even did a quick google search, and the only thing I could come up with is the toe alignment of an automobile's wheels.
    A ride a day keeps the therapist away.

  18. #43
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    yep, the three just refer to how you want the rim to look. I've attached a photo showing the three patterns. 3k is a tight weave, 12k bigger weave, UD no weave. you can also get them with or without the glossy finish.

    I happened to choose 12k matte finish. Plan to build them up with some Hope hubs.

    @vwn8: glad to hear yours are running well!
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    A ride a day keeps the therapist away.

  19. #44
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    Tow alignment: WTF?

    Quote Originally Posted by Jwiffle View Post
    I do build wheels (well, I've built about a dozen). And none of the sources I ever used when learning to build wheels (Brandt's book, Brown's site, fellow mechanics) ever mentioned "tow alignment."

    I believe what he is referring to is that he doesn't trust a "cheap" carbon wheel but didn't have any reason to not to, so made something up, seeing as the term is just made up. I even did a quick google search, and the only thing I could come up with is the toe alignment of an automobile's wheels.
    Exactly. After researching tow alignment, I concluded it's the bicycle equivalent of the flux capacitor on the DeLorean.
    Brisbane, AU

  20. #45
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    Quote Originally Posted by Jwiffle View Post
    I do build wheels (well, I've built about a dozen). And none of the sources I ever used when learning to build wheels (Brandt's book, Brown's site, fellow mechanics) ever mentioned "tow alignment."

    I believe what he is referring to is that he doesn't trust a "cheap" carbon wheel but didn't have any reason to not to, so made something up, seeing as the term is just made up. I even did a quick google search, and the only thing I could come up with is the toe alignment of an automobile's wheels.
    Quote Originally Posted by hootsmon View Post
    Exactly. After researching tow alignment, I concluded it's the bicycle equivalent of the flux capacitor on the DeLorean.
    Yup! I just made it up because I don't know what I'm talking about!!!! Not need to read any further in this crap I write. Or perhaps i didn't make it up and I've worked as a composites process engineer in one of the county's foremost composites research labs, but, like most engineers, "don't English real well"?

    Sorry I didn't see the question sooner, or make my comment more easy to understand in the first place.

    Fiberglass filaments are collected in what is traditionally called roving. Carbon fiber filaments are collected into what are traditionally called tows. So the bundles of filaments in the weave or braid used to make the rims are made up of tows.

    Here is the first google result I found with what i assume is a validating explanation of tows and roving:

    Fibermax Composites - TOW / YARN NOMENCLATURE AND CODING SYSTEMS

    Since carbon composite is an anisotropic material (in part the reason things made with it can be so light and still function properly, the strength and stiffness can be concentrated in the correct orientation, rather than being evenly distributed in all directions in isotropic materials like metals), the alignment of the tows is extremely important. If the orientation is off, more material is needed to provide the same strength and stiffness. Alternately, if the orientation is off, and the amount of material used was calculated presuming proper alignment, the part will fail in service. If these were super heavy, they would probably be fine, but then what would be the point of using carbon. I expect, like most things out of China the quality is variable, and some of these will be fine, and others will not. Thermosetting carbon composites exhibit a brittle failure mode (that's like glass, rather than like metal). Not a good failure more for bicycle rims, in my opinion. Does that help clear things up?

    Oh, and to the person who thought i was talking about automotive wheel alignment, that's toe, not tow.

  21. #46
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    Quote Originally Posted by rocwandrer View Post
    Yup! I just made it up because I don't know what I'm talking about!!!! Not need to read any further in this crap I write. Or perhaps i didn't make it up and I've worked as a composites process engineer in one of the county's foremost composites research labs, but, like most engineers, "don't English real well"?

    Sorry I didn't see the question sooner, or make my comment more easy to understand in the first place.

    Fiberglass filaments are collected in what is traditionally called roving. Carbon fiber filaments are collected into what are traditionally called tows. So the bundles of filaments in the weave or braid used to make the rims are made up of tows.

    Here is the first google result I found with what i assume is a validating explanation of tows and roving:

    Fibermax Composites - TOW / YARN NOMENCLATURE AND CODING SYSTEMS

    Since carbon composite is an anisotropic material (in part the reason things made with it can be so light and still function properly, the strength and stiffness can be concentrated in the correct orientation, rather than being evenly distributed in all directions in isotropic materials like metals), the alignment of the tows is extremely important. If the orientation is off, more material is needed to provide the same strength and stiffness. Alternately, if the orientation is off, and the amount of material used was calculated presuming proper alignment, the part will fail in service. If these were super heavy, they would probably be fine, but then what would be the point of using carbon. I expect, like most things out of China the quality is variable, and some of these will be fine, and others will not. Thermosetting carbon composites exhibit a brittle failure mode (that's like glass, rather than like metal). Not a good failure more for bicycle rims, in my opinion. Does that help clear things up?

    Oh, and to the person who thought i was talking about automotive wheel alignment, that's toe, not tow.
    Thank you. I appreciate it. That top layer is simply cosmetic, however. Like a lot of carbon fiber, most of the rim is UD. Taking that into consideration, does it really matter if the cosmetic layer does not have a higher quality tow? It really only matters if the UD has the desired tow...?
    I am immune to your disdain.

  22. #47
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    Quote Originally Posted by vwn8 View Post
    Ive been on my set for about 50-100miles now. Built them with AC hubs and Sapim CX-rays. Im 200-215lb and im not babying them. So far theyve been great! I have a set of AC XCs and a set of hope/stan 355s and these are easily my favorites. The ride quality is much better. They feel as stiff as anything else and theyre the lightest by quite a bit (very low 1500g range). If your on the fence about these I would say go for it!

    One thing I should mention is I had mine built with the "old" layup. Im told 390g rims are the new layup. Mine are 415g.
    Just to be clear, when you say 'my set', are you referring to the light-bicycle/Xiamen BECS rims? which version? and of course the obvious question millions are wondering -- how suitable are they for tubeless?

    thanks.
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  23. #48
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    Quote Originally Posted by indyfab25 View Post
    Thank you. I appreciate it. That top layer is simply cosmetic, however. Like a lot of carbon fiber, most of the rim is UD. Taking that into consideration, does it really matter if the cosmetic layer does not have a higher quality tow? It really only matters if the UD has the desired tow...?
    I was just talking about orientation, not the material quality. Like steel or aluminum, different grades have different properties. With carbon, not just the strength, but also the stiffness varies with the material grade. That's a whole other can of worms.

    As far as orientation, like anything, the answer is "it depends." I don't know the layup schedule for the rims, so it is hard to answer for sure. Also, so many different directions I could go with how to use plain english to explain my thinking... here are a couple incomplete thoughts... Number two was what I was thinking when i made my comment.

    1.) My intuition is that those tows do not look particularly spread, yet they are wide, meaning they are relatively heavy tows (I'm guessing 3k for the "cosmetic" layer in the original photos i commented on). There simply isn't any room in the total weight of a light weight rim for a cosmetic layer. The cosmetic layer also performs the function of providing some of the the needed cross direction strength and stiffness, shear reinforcement, etc. If the fibers were all uni-hoop oriented, the rim would probably crack open just from the inflation pressure of the tire.

    2.) If you can't be bothered to get the cosmetic layer that shows (which is also structurally significant) reasonably well oriented on the rim you use for the promotional photos for the product, how well could you possibly have done the parts that don't show on the every day production unit?

    3.) Since composites are anisotropic (not the same properties in all directions), symmetry is important in symmetrically stressed parts.

  24. #49
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    Quote Originally Posted by rocwandrer View Post
    Yup! I just made it up because I don't know what I'm talking about!!!! Not need to read any further in this crap I write. Or perhaps i didn't make it up and I've worked as a composites process engineer in one of the county's foremost composites research labs, but, like most engineers, "don't English real well"?

    Sorry I didn't see the question sooner, or make my comment more easy to understand in the first place.

    Fiberglass filaments are collected in what is traditionally called roving. Carbon fiber filaments are collected into what are traditionally called tows. So the bundles of filaments in the weave or braid used to make the rims are made up of tows.

    Here is the first google result I found with what i assume is a validating explanation of tows and roving:

    Fibermax Composites - TOW / YARN NOMENCLATURE AND CODING SYSTEMS

    Since carbon composite is an anisotropic material (in part the reason things made with it can be so light and still function properly, the strength and stiffness can be concentrated in the correct orientation, rather than being evenly distributed in all directions in isotropic materials like metals), the alignment of the tows is extremely important. If the orientation is off, more material is needed to provide the same strength and stiffness. Alternately, if the orientation is off, and the amount of material used was calculated presuming proper alignment, the part will fail in service. If these were super heavy, they would probably be fine, but then what would be the point of using carbon. I expect, like most things out of China the quality is variable, and some of these will be fine, and others will not. Thermosetting carbon composites exhibit a brittle failure mode (that's like glass, rather than like metal). Not a good failure more for bicycle rims, in my opinion. Does that help clear things up?

    Oh, and to the person who thought i was talking about automotive wheel alignment, that's toe, not tow.
    I appreciate you coming back to the discussion. Those of us who don't work with carbon directly have never heard of tow alignment. And a google search for 'tow alignment' only brought up 'toe alignment' responses. And when you made a statement without any explanation, then disappeared from the discussion, the rest of us were left to assume you were just trolling.

    You're assuming the outer layer is structural. Some of the name brand carbon rims have significantly lower claimed weights, so it may be possible the outer layer is not structural, but I wouldn't actually know, just going by what you said about the need for it to be structural due to the weight.

    Anyway, now that I understand that you are referring to the pattern of the weave, I can see what you are referring to in the 4th picture (I think - at least, that one seems to have a somewhat strange pattern).

    Guess I'll find out how well they hold up. They offer a year warranty. And as cheap as they are, I figure they're worth a shot.
    A ride a day keeps the therapist away.

  25. #50
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    Does this qualify for an "Oh Snap?"

    Quote Originally Posted by rocwandrer View Post
    Yup! I just made it up because I don't know what I'm talking about!!!! Not need to read any further in this crap I write. Or perhaps i didn't make it up and I've worked as a composites process engineer in one of the county's foremost composites research labs, but, like most engineers, "don't English real well"?


    Why yes, I believe it does!

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