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  1. #51
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    Quote Originally Posted by rocwandrer View Post
    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.
    The carbon is Toray 800 which is somewhere on the higher end of the grades from what I have researched. Please correct me if I am wrong. If the UD rims are completely UD including the cosmetic layer, and the carbon is Toray 800, seems like a quality rim with regard to material used. Is there a tow to UD?
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  2. #52
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    Quote Originally Posted by indyfab25 View Post
    The carbon is Toray 800 which is somewhere on the higher end of the grades from what I have researched. Please correct me if I am wrong. If the UD rims are completely UD including the cosmetic layer, and the carbon is Toray 800, seems like a quality rim with regard to material used. Is there a tow to UD?
    Toray is a reputable manufacturer of carbon fiber, and T800 is a high grade product. I know nothing about the manufacturer of the rims and don't want to imply I have any special insider info, but it is suspect that they call out T800 as the material... So far as i know, T800 is a bit hard to get your hands on now as Boeing is snapping it all up. It also only comes in 6k and 12k tows, so far as I know.

    As far as "is there a tow to UD?" I don't understand the question.

  3. #53
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    Quote Originally Posted by rocwandrer View Post
    Toray is a reputable manufacturer of carbon fiber, and T800 is a high grade product. I know nothing about the manufacturer of the rims and don't want to imply I have any special insider info, but it is suspect that they call out T800 as the material... So far as i know, T800 is a bit hard to get your hands on now as Boeing is snapping it all up. It also only comes in 6k and 12k tows, so far as I know.

    As far as "is there a tow to UD?" I don't understand the question.
    Is there a tow to UD? You mentioned the tow was off in one of the pics. Does UD have tow? If it is off, how do you tell? It doesn't look like UD has a tow size, but it has to.

    They call the material T800. I have seen this and other manufacturers use that terminology(Toray800 and T800) interchangeably.

    Toray Carbon Fibers America - Application Information
    Lots of cool info there. I just learned a bunch.
    Last edited by indyfab25; 01-15-2012 at 07:53 PM.
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  4. #54
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    Quote Originally Posted by indyfab25 View Post
    Is there a tow to UD? You mentioned the tow was off in one of the pics. Does UD have tow? If it is off, how do you tell? It doesn't look like UD has a tow size, but it has to.

    They call the material T800. I have seen this and other manufacturers use that terminology(Toray800 and T800) interchangeably.

    Toray Carbon Fibers America - Application Information
    Lots of cool info there. I just learned a bunch.
    "Tow" is a noun meaning a bundle of filaments. UD is a noun abbreviation meaning unidirectional. unidirectional fabric is made from tows, which are by definition unidirectionally oriented. The tow size is much less important with unidirectional fabric, but still a mfg parameter.

    I see you edited your reply, but if i understood correctly, the issue is that T800 is a high, not standard modulus product in Toray product nomenclature.

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    oh, and "does UD have tow?" what you really mean might be "does UD have/require alignment?" The answer is a resounding yes. And the pictures tell me nothing about the accuracy or correctness of that alignment.

  6. #56
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    Quote Originally Posted by rocwandrer View Post
    "Tow" is a noun meaning a bundle of filaments. UD is a noun abbreviation meaning unidirectional. unidirectional fabric is made from tows, which are by definition unidirectionally oriented. The tow size is much less important with unidirectional fabric, but still a mfg parameter.

    I see you edited your reply, but if i understood correctly, the issue is that T800 is a high, not standard modulus product in Toray product nomenclature.
    Okay. Tow size with UD is less important. Does that mean that UD is generally stronger, as some other carbon manufacturers report?

    I did edit my reply as I was learning after the post and answering questions and learning that some of my statements were wrong.

    There appears to be several variations of the T800.

    Thanks again for the info. If you are getting sick of answering my questions please point me to a couple sites or places I can learn more about this.
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  7. #57
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    this is extremely interesting, any more hands on reports?

  8. #58
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    Quote Originally Posted by indyfab25 View Post
    Okay. Tow size with UD is less important. Does that mean that UD is generally stronger, as some other carbon manufacturers report?

    I did edit my reply as I was learning after the post and answering questions and learning that some of my statements were wrong.

    There appears to be several variations of the T800.

    Thanks again for the info. If you are getting sick of answering my questions please point me to a couple sites or places I can learn more about this.
    First an FYI, most composites folks say "uni" as short for unidirectional, not UD, but they are the same thing.

    I'm not in the habit of looking for basic composites resources on the net, but I'll suggest:

    ACMA: Technical Resources <-- lots of irrelevant stuff about regulations, business, etc, but most of the basic stuff is technically accurate, and including the link throughs, the pit of info is bottomless. Bonus, it is vetted for minimal product bias (some types more innocuous types are allowed, by rule). Many seemingly reputable sources of easy to understand technical info about composites (probably including me to some degree, if i ever manage to be easy to understand) are not totally accurate. One reason is composites are really complicated, and not easy to understand, so simplifications to make stuff easy to understand automatically seem to end up distorting the truth. The (unfortunately more common) reason is that consumers are poorly educated about composites, so marketing departments can pretty much say anything that sounds believable to make their stuff sound good.

    Not really because of tow size being less important, but yes, in general a very well designed and executed unidirectional layup will dramatically outperform a very well designed woven or braided composite. Part of the reason is that on a weight basis, the fiber is more structurally efficient, and you can use less resin and more fiber with uni. Layups made from all uni also tend to be less error tolerant (design, placement, and infusion/impregnation/compaction/consolidation) though. With most consumer products, a braided or woven layer is used for cosmetics on the surface, but that layer is also very structurally useful for crack prevention and shear transfer,etc in an otherwise uni product.

  9. #59
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    Any real experiences with buildup and riding?

    I've been thinking about building up a pair of these just to see how they go. Anyone know the ERD?

  10. #60
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    Quote Originally Posted by nbwallace View Post
    I've been thinking about building up a pair of these just to see how they go. Anyone know the ERD?
    We measured 603.
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    Thanks indyfab

    I assume the build went without incident.

  12. #62
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    Quote Originally Posted by nbwallace View Post
    I assume the build went without incident.
    No issues at all. Nice and stiff. Taped the rim, threw some sealant in, and the tire is still holding air. Tubeless was a breeze.
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    That's very encouraging

    Thanks indyfab. That may make the decision to build these up a no brainer. With Stan's rims at around $90 each (maybe $85) the price is certainly reasonable. The web site makes it sound as if these rims are 75 grams lighter than the Arches. That could make for a really nice set of tubeless wheels.

  14. #64
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    The AM 29r rim weighs around 440g. Tubeless is very good. We have a 28 hole rim here that I threw a Nobby Nic on to test without sealant. Blew up and held air no problem.
    I might build a set up with I9 Enduro wheels. That would be sick.
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  15. #65
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    Here is a pic of the rim bed and bead.
    Attached Thumbnails Attached Thumbnails (Cheap) Chinese Carbon Rims?-p10005131.jpg  

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  16. #66
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    Quote Originally Posted by indyfab25 View Post
    Much, much higher.
    ...
    According to Guitar Ted, Reynolds rims go from 950 1150 N.
    Much, much higher than what? He didn't say what tension the "crack" developed at, and 950-1150N is not high, it's average... for aluminum rims.
    Quote Originally Posted by pvd
    Time to stop believing the hype and start doing some science.
    29er Tire Weight Database

  17. #67
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    Quote Originally Posted by meltingfeather View Post
    Much, much higher than what? He didn't say what tension the "crack" developed at, and 950-1150N is not high, it's average... for aluminum rims.
    That is a good question. Honestly, I do not know. You raise a good point. I was relying on Reynold's opinion that carbon rims can handle higher tensions. If I am not mistaken, that came from the interview on 29inches.com.
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  18. #68
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    Quote Originally Posted by indyfab25 View Post
    The AM 29r rim weighs around 440g. Tubeless is very good. We have a 28 hole rim here that I threw a Nobby Nic on to test without sealant. Blew up and held air no problem.
    I might build a set up with I9 Enduro wheels. That would be sick.
    I've checked through this thread and it wasn't totally clear to me, where did you order these rims? Thanks for the info.

  19. #69
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    Quote Originally Posted by hillharman View Post
    I've checked through this thread and it wasn't totally clear to me, where did you order these rims? Thanks for the info.
    Xiamen BECS.
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  20. #70
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    Quote Originally Posted by indyfab25 View Post
    Xiamen BECS.
    Sorry for being dense, but is there a link where the product can be ordered? I'm not having much luck with Google.

    Edit: I think I found it: bikes 29er super light rim products, buy bikes 29er super light rim products from alibaba.com

  21. #71
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    Quote Originally Posted by AZ.MTNS View Post
    Okay, I did not realize that was a crack, it looks like a scribe line in the photo. Thanks.
    It doesnt look like a crack at all

  22. #72
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    I am immune to your disdain.

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    Quote Originally Posted by hillharman View Post
    I've checked through this thread and it wasn't totally clear to me, where did you order these rims? Thanks for the info.
    looks like they making it easier to order

    carbon 29er wheel mountain bike clincher - light-bicycle

  24. #74
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    Quote Originally Posted by bigdog100 View Post
    looks like they making it easier to order

    carbon 29er wheel mountain bike clincher - light-bicycle
    I wonder if those hubs are any good. The price for the full wheelset is crazy.

  25. #75
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    Indyfab, what's the kind of spoke tension you've used for the build? The range I got from light-bicycle.com was a tad hight.

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