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  1. #6601
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    Re: (Cheap) Chinese Carbon Rims?

    Quote Originally Posted by yourdaguy View Post
    Well I knew about galvanic corrosion decades before the 2001 start of Wikipedia. I had 2 wheels with broken nipples this Summer and rebuilt them with brass and I just rebuilt the other 6 in the last 2 weeks using brass. Here is a sampling of the damage I found.

    https://www.dropbox.com/sc/apd0zahc3...pWyY9elieN7bma

    Sure looks like galvanic corrosion to me. These nipples have been in there around 2 years. I wash my bikes about every 3rd ride and I ride a lot-like 5 times a week.

    https://www.dropbox.com/sc/2w5zzgwvj...4sri3mNYJYKLja

    I have 3 sets of Stans wheels some of them 5 years old and so far no nipple problems. So my theory is that it is galvanic corrosion caused by the carbon (which is drilled no molded-that should make it worse) and the more you wash/get them wet, the worse the problem.

    Tell us MF, what is your theory on what is happening?
    So the nipple disintegrates, but the carbon around the nipple is just fine, and maintains its structural integrity?
    Thanks in advance for answering.

  2. #6602
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    (Cheap) Chinese Carbon Rims?

    Quote Originally Posted by yourdaguy View Post
    Tell us MF, what is your theory on what is happening?
    I've spelled it out a few times, and since I stopped taking you seriously after the 5th or 6th complete BS post I saw from you, I'm not going to waste my time (again).
    Since you know what galvanic corrosion looks like (you probably don't even understand why that's funny), have you ever wondered why this corrosion only exhibits inside the rim cavity? Or why galvanic corrosion is not a problem in the numerous other places on a bicycle where carbon and aluminum are in contact?
    Quote Originally Posted by pvd
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  3. #6603
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    The way it works genius is the aluminum becomes an anode and the free elections

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  4. #6604
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    Cause the aluminum to lose its bonds just like a battery. Sorry about the split post, I am doing this from my phone between laps.

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  5. #6605
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    Quote Originally Posted by yourdaguy View Post
    Well I knew about galvanic corrosion decades before the 2001 start of Wikipedia. I had 2 wheels with broken nipples this Summer and rebuilt them with brass and I just rebuilt the other 6 in the last 2 weeks using brass. Here is a sampling of the damage I found.

    https://www.dropbox.com/sc/apd0zahc3...pWyY9elieN7bma

    Sure looks like galvanic corrosion to me. These nipples have been in there around 2 years. I wash my bikes about every 3rd ride and I ride a lot-like 5 times a week.

    https://www.dropbox.com/sc/2w5zzgwvj...4sri3mNYJYKLja

    I have 3 sets of Stans wheels some of them 5 years old and so far no nipple problems. So my theory is that it is galvanic corrosion caused by the carbon (which is drilled no molded-that should make it worse) and the more you wash/get them wet, the worse the problem.

    Tell us MF, what is your theory on what is happening?
    Are you a metallurgist? If so, can you explain the difference visually between corrosion and galvanic corrosion?

    Had worse looking corrosion that destroyed a wheelset in 2 months - of course the wheelset was aluminium nipples and aluminium rims, the cause was probably poor nipple quality( no anodising or coating) and salt water

  6. #6606
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    Corrosion and Galvanic corrosion are basically the same thing with the exception that galvanic corrosion tends to have another metal driving the process faster than would naturally happen. When metal corrodes it is basically oxydation.

    When you put an aluminum lawn chair out it turns a dull color that is a surface layer of corrosion (actually aluminum oxide) that is fairly hard. This prevents the aluminum from further oxidizing for the most part and the bare aluminum chair lasts for a decade or so. The same is true of rust which is basically corroded iron. That is why the Picasso statue in Chicago does not turn into a pile of iron oxide, the metal is thick enough (and alloyed with a few other metals to slow down the process) that the iron below the surface can't be gotten to by the air and further oxidized.

    This oxidation process is basically the metal losing electrons and then the oxygen in the atmosphere combines with the metal to form an oxide (iron oxide is rust, aluminum oxide is the surface patina on aluminum lawn furniture, etc.) The galvanic potential of a metal is a measure of how easy it is for that metal to lose electrons and get oxidized. If you put 2 metals with different galvanic numbers in contact, the one with the greatest galvanic potential will tend to shed the electrons for the entire system (it is more complicated than this-but without writing a book...) The metal that sheds the electrons will corrode way more deeply and rapidly than it normally would because the overall electrical potential is focused into the point of least resistance. This point becomes the natural anode for what is in effect a very weak battery.

    The reason that mine corroded so much on the ends was that I thought galvanic corrosion could be a problem and I built my wheels (after the first set) with never seize on the threads and the head where it seats on the rim. The way never seize works is that it is grease that has either ground up copper (the brown kind-what I used) or ground up aluminum or magnesium or both (the silver kind) to both allow electrons to flow between the parts and also to be somewhat a sacrificial metal. So the main place left in this case for electrons to leave would be the head of the nipple. What you didn't see was that the 2 wheels that I didn't use never seize on the spokes were corroded to the nipples and I actually had to cut 2 spokes because I could not get the nipple to turn and if you notice in the picture the pieces of broken nipple shaft, those were from the first wheel set where the nipples were literally welded to the spokes.

    Generally, all of this is a bad thing, but if you look up "sacrificial anode" (don't do it on Wikipedia or MF will dis you), there are some very good uses of this effect such as putting blocks of magnesium on the hulls of steel ships to keep them from rusting much at all for decades. Magnesium, by the way, is one of the most galvanic metals and it is very hard to keep parts made of magnesium from corroding or having galvanic corrosion issues if they are even near other metals. The US military has spent untold $ trying to prevent magnesium from corroding since it is very light and strong (2 things they like) but to this day, they only use it in limited applications because of this.

    Pharmaboy: salt is a definite catalyst for oxidation since pure water is not very conductive, but the more ions of salt you have in water the better it conducts. Salt water loves to move those electrons from the metal. In fact, that is what the military uses to test the effectiveness of anti corrosion measures. They will subject a part to several days of misted salt spray which generally represents years of actual use in most applications that are not marine in nature.

    I am not a metallurgist and I do not play one on TV but I do have a little bit of a physics background although this is a chemists realm so while i have a basic understanding if you want nitty gritty details you will need a non-organic chemist or a metallurgist.
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  7. #6607
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    (Cheap) Chinese Carbon Rims?

    Quote Originally Posted by yourdaguy View Post
    Cause the aluminum to lose its bonds just like a battery. Sorry about the split post, I am doing this from my phone between laps.

    Sent from my G3 using Tapatalk.
    I know how it works, which is why it doesn't seem at all to be galvanic.
    It looks like straight attack on the unanodized aluminum, most likely by ammonia. IIRC ENVE even recommended or supplied Gorilla tape with their wheels. Gorilla is porous and allows diffusion of ammonia through it.
    The lack of consistency of this problem is another strong clue. Carbon rims have been in use on road bikes for many years, wet conditions, washing... everything you're trying to tie to galvanic... but without sealant containing ammonia. Don't know that I've heard of or seen a single instance of this on road bikes. Galvanic corrosion is something that happens every time the recipe is there... every time.
    Quote Originally Posted by pvd
    Time to stop believing the hype and start doing some science.
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  8. #6608
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    "Corrosion and Galvanic corrosion are basically the same thing with the exception that galvanic corrosion tends to have another metal driving the process faster than would naturally happen. When metal corrodes it is basically oxydation."

    From reading, all galvanic corrosion is corrosion but not all corrosion is galvanic. Galvanic is specific to dissimilar metals, and is a type of corrosion, and by most accounts a not too common one, but one to be aware of ( as a one time house renovator in a seaside suburb, one has to be acutely aware of the interaction of disimilar metals on housing).

    I do not think you can identify the type by looking, and there is plenty of cause for doubt in this situation.

    All in all though, I still hold that aluminium is a stupid material for a nipple, and the 30grams of weight is only important inside the mind of a true weight weenie who lacks complete rationality and somehow thinks that they can buy speed rather than earn it

  9. #6609
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    I use the Bontrager rim strips on all my carbon wheels. The only possible place the sealant could get in between the top and bottom of the rim where the nipples seat is through the valve stem and there is no evidence of that. I use Stan's valves and I really tighten them up. I can't believe that the Bontrager rim strips are permeable by ammonia, but I guess that is a possibility.

    Are the spoke holes on road carbon wheels drilled or molded? Molded wheels would theoreticalls only have resin touching nipples which is somewhat of an insulator so I would expect almost no corrosion. I was a roadie for many years and rode over 5000 miles annually and probably 30-40% of it on Zipp wheels and I never had a problem with nipples breaking but I have broken a few of those outrageously expensive spokes. If Zips are drilled, does Zip go back and put resin or sealer in the holes? If the Zipps are drilled, do they leave carbon out of the place where they drill them? That could certainly explain all the spoke pull through issues they had prior to 2005 or so. I know that the Lb wheels are drilled right through the carbon so the carbon fibers will generally be in contact with the nipples.

    There have been several reports of galvanic corrosion on Enve rims even though their nipple holes are molded. Is it possible that even though theirs are molded that the carbon fibers on theirs are coming to the top of the resin in the holes? Or, as you suspect, it is ammonia permeating through the Gorilla tape. Do you know for sure that ammonia will permeate through Gorilla Tape?


    Given all of the above, if everything we think we know is true...
    One possibility that tends to make sense on all counts is that the ammonia is the catalyst and that is why road bikes never had the problem and if Gorilla Tape and Rim strips are permeable to ammonia, then the ammonia is acting as a catalyst and causing the corrosion. If this is true, then it explains my issues, and Enve's issues and the fact that road carbon wheels didn't suffer from this problem. Also, if Stan's tape is not permeable then it would explain why some are suffering this problem and others are not.
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  10. #6610
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    (Cheap) Chinese Carbon Rims?

    Quote Originally Posted by yourdaguy View Post
    There have been several reports of galvanic corrosion on Enve rims even though their nipple holes are molded.
    Corrosion... there have been reports of corrosion.
    It doesn't seem to be and we don't know at this point, so tagging the word galvanic on every time you write corrosion is useless and probably wrong.
    That has sort of been my point.
    Quote Originally Posted by yourdaguy View Post
    One possibility that tends to make sense on all counts is that the ammonia is the catalyst and that is why road bikes never had the problem and if Gorilla Tape and Rim strips are permeable to ammonia, then the ammonia is acting as a catalyst and causing the corrosion.
    Ammonia in this situation is a corrosive acid, not a catalyst.
    Quote Originally Posted by pvd
    Time to stop believing the hype and start doing some science.
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  11. #6611
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    All corrosion is not galvanic but galvanic corrosion is corrosion that is driven by the different electrical potentials of the metals involved. The stainless spokes and aluminum nipples definitely would provide electrical potential.

    A catalyst is any chemical that speeds up a reaction. Ammonia is definitely a catalyst in this case or else we can't blame the ammonia.
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  12. #6612
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    Has anyone experienced this issue with alu wheels running tubeless setups?

  13. #6613
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    Quote Originally Posted by abelfonseca View Post
    Has anyone experienced this issue with alu wheels running tubeless setups?
    Yes, but many stupid deep creek crossings also involved (el nino years). Nipples spun off easy because of the permatex anti-seize I used on the threads.

  14. #6614
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    If the stans was the issue, shouldn't people's alum rims be disintegrating? Instead of just the nipples.

  15. #6615
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    (Cheap) Chinese Carbon Rims?

    Quote Originally Posted by abelfonseca View Post
    Has anyone experienced this issue with alu wheels running tubeless setups?
    Yes
    Quote Originally Posted by pvd
    Time to stop believing the hype and start doing some science.
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  16. #6616
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    (Cheap) Chinese Carbon Rims?

    Quote Originally Posted by mtndude23 View Post
    If the stans was the issue, shouldn't people's alum rims be disintegrating? Instead of just the nipples.
    No, The rims and most aluminum nipples are anodized, which provides protection against corrosion. Also, in a proper tubeless set up neither the nipples nor the rims are exposed to sealant.
    This appears to be the result of unanodized nipples, which are not very common, and crappy gorilla tape, which ENVE recommended and I believe supplied with their wheels.
    Quote Originally Posted by pvd
    Time to stop believing the hype and start doing some science.
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  17. #6617
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    (Cheap) Chinese Carbon Rims?

    Quote Originally Posted by yourdaguy View Post
    All corrosion is not galvanic but galvanic corrosion is corrosion that is driven by the different electrical potentials of the metals involved. The stainless spokes and aluminum nipples definitely would provide electrical potential.

    A catalyst is any chemical that speeds up a reaction. Ammonia is definitely a catalyst in this case or else we can't blame the ammonia.
    There you go again.
    You admit that you don't know chemistry yet here you are trying to split semantic hairs (and getting it completely wrong, btw).
    Would it be totally unacceptable for you to keep your mouth shut when you don't know you're talking about?
    Due to your unfortunate combination of ignorance and prolific posting, you are a big part of the reason why there is confusion about the corrosion issue.
    Quote Originally Posted by pvd
    Time to stop believing the hype and start doing some science.
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  18. #6618
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    I am not splitting hairs. You are pissed because I pointed out that as usual you are not providing an good information just belittling people and running them off the site. My statements that you quoted are a fact and the intelligent members know you are just a wind bag.

    As to your point about tagging the word galvanic every time I write corrosion that is not true. What is true is that aluminum lawn furniture will last for decades, if you put a steel screw in it it will turn to mush in that area. That is galvanic corrosion. The patina that was on there before the screw was corrosion. What we are seeing with the nipples is definitely galvanic corrosion whether you want to call it that or not. AS usual, you take the argument to yelling that "we can't prove galvanic corrosion" -well yes we can; intelligent people look at the pictures -people who know what galvanic corrosion looks like and they say-yes that is it. You continue to make false claims about my statements as though your claims are a fact. All you do is confuse the weak minded and look like an idiot to the smart.

    Why don't you do something useful like run a test of Gorilla tape rear wheel, Stan's tape front wheel and report back in a year? You need to get over yourself. Everyone that comes on this forum is going to make mis-statements and errors, but you are always the first one to jump on and call them stupid. The exchange of ideas is how we all get smarter not by one guy running people off that don't see things his way.

    I encourage anyone who has any doubt to look through his posts and see what percentage are him telling someone that they are stupid and don't know anything and probably uses Wikipedia, etc.

    MF, I have tried to be nice to you in the past and complimented when you actually helped someone, etc. but you just look for me to post and then jump all over it. I spent half an hour writing a detailed explanation of galvanic corrosion that is probably one of the longest posts in this thread packed with good information. It was valuable information to the other readers. You come back with : you don't take me seriously since my posts are BS (your post 6602). Who is doing the most the further the goals of this forum?
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  19. #6619
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    Are having a biology discussion or carbon rims? Can you guys stay on topic? Any word on 29er 35mm oval shaped wheels coming out anytime soon? I think I remember seeing someone post this. I dont want to buy derby's. Its like getting 3 Chinese rims for 2 derby's which may be worth it in the long haul with their current t sale going on

  20. #6620
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    Quote Originally Posted by Tonggi View Post
    Are having a biology discussion or carbon rims? Can you guys stay on topic? Any word on 29er 35mm oval shaped wheels coming out anytime soon? I think I remember seeing someone post this. I dont want to buy derby's. Its like getting 3 Chinese rims for 2 derby's which may be worth it in the long haul with their current t sale going on
    It is on topic, the issue has existed for quite some time with much misinformation having been posted here and in many other forums. I for one welcome the discussion as it helps to dispel much of that misinformation.

  21. #6621
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    Quote Originally Posted by yourdaguy View Post
    I am not splitting hairs. You are pissed because I pointed out that as usual you are not providing an good information just belittling people and running them off the site. My statements that you quoted are a fact and the intelligent members know you are just a wind bag.
    I and a few others have provided the little good info on corrosion that has been posted.
    I'm not pissed at all, just providing some good information to balance out the volumes of crap that you spew.
    Calling a corrosive acid reactant a catalyst is ignorant... trying to justify it with some general description of what a catalyst is is semantic hair splitting. Simple... and typical of what you do day in and day out.
    If you would stop posting misinformation to the detriment of the forum people like myself and others wouldn't feel compelled to correct your crap.
    All the thousands of words of copy-and-paste on corrosion that you post does not provide useful information to this discussion... it continues to confuse the issue.
    It's not about running people off or seeing things my way, it is about providing good information for people to use as a resource, which is why you often find yourself on the receiving end of corrections, not only by me but by plenty of posters who actually know something about the various topics you post on.
    I'm not lapping this with you again.
    Continue to post ignorant and misinformed crap and you will probably continue to see the same responses.
    I will be the first to compliment you on a good forum contribution if I ever see one.
    Here's to hoping...
    Quote Originally Posted by pvd
    Time to stop believing the hype and start doing some science.
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  22. #6622
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    Calling a corrosive acid a catalyst is correct when it is acting as such. Your refusal to even concede that point just shows your intransigence. Saying that I posted thousands of words of cut and paste is just a lie. There is nothing in my post that is cut and pasted; in fact I seldom ever cut and paste. I would generally provide a link so that the party can perceive the context of the information. You on the other hand are probably a prolific cut and paster.
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  23. #6623
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    In order to really prove our theories and hypothesis on this whole corrosion deal, all it takes is a little design of experiments. where the variables could be as follows: true being manifestation of corrosion and false being no corrosion. Assuming all are using alloy niples

    x- carbon rims setup tubeless with stans and gorilla tape
    y- carbon rims with tubes
    z- carbon rims setup tubeless with stans and stans tape
    m- carbon rims setup tubeless with non amonia selant and gorilla tape
    u- alu rims setup tubeless with stans and gorilla tape
    o- alu rims setup tubeless with stans and stans tape
    t- alu rims setup tubeless with non amonia sealant and gorilla tape

    If lets say: x y z m all hold true and u,o,t all hold false, then we can assume its not the sealant or gorilla tape to blame but another factor (galvanic corrosion)
    If x,u hold true then, stans gorilla combination is the culprit, more likely due to amonia going past the gorilla tape.

    and we can reach other conclusions with the other combinations.
    This is just an example.

    Cheers

  24. #6624
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    Yes and don't forget that all my wheels have Bontrager rim strips. Unfortunately since I rebuilt all my wheels with brass I am not able to test this stuff any more. It would be good for those with nipple corrosion to report all their pertinent parameters so we can get a better idea. Also, anyone that goes years with no nipple corrosion it would be good to hear from them with their parameters.

    Me:
    Home made sealant: ammonia, latex, pg, ro water, various chunkulators over time
    Bontrager rim strips
    fairly frequent washing of bike
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  25. #6625
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    Quote Originally Posted by yourdaguy View Post
    Calling a corrosive acid a catalyst is correct when it is acting as such.
    Here's some cut-and-paste for you:
    "catalyst - a substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change."
    Reactants are not catalysts. Period.
    Keep posting ignorant crap and you will keep getting corrected.
    Quote Originally Posted by pvd
    Time to stop believing the hype and start doing some science.
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  26. #6626
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    I have defined catalyst every time you dissed me about it as a substance that increases the speed of a chemical reaction. I left of the without undergoing a permanent chemical change because I thought that was self evident. Apparently, you are someone for which every aspect of every thing has to be spelled out to. I will patronize you like a child in the future.
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  27. #6627
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    (Cheap) Chinese Carbon Rims?

    Quote Originally Posted by yourdaguy View Post
    I have defined catalyst every time you dissed me about it as a substance that increases the speed of a chemical reaction. I left of the without undergoing a permanent chemical change because I thought that was self evident. Apparently, you are someone for which every aspect of every thing has to be spelled out to. I will patronize you like a child in the future.
    I guess you don't understand that ammonia undergoes chemical reaction/change in this scenario?
    Why is that not surprising.
    Look at how much time is wasted because you're posting things you have no idea about.
    I think it's pretty obvious to anyone who reads the forum where you're coming from and hopefully they attribute the appropriate level of credibility (zero).
    The catalyst thing was just a convenient example of the type of thing you say all the time that is demonstrably false, as if you had said, "the earth is flat, so therefore..."
    And I'm the one who needs things spelled out? lol
    Quote Originally Posted by pvd
    Time to stop believing the hype and start doing some science.
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  28. #6628
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    The ammonia is not combining with the metal. The metal is combining with oxygen.
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  29. #6629
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    (Cheap) Chinese Carbon Rims?

    Quote Originally Posted by tiretracks View Post
    It is on topic, the issue has existed for quite some time with much misinformation having been posted here and in many other forums. I for one welcome the discussion as it helps to dispel much of that misinformation.
    I haven't read a single post regarding Chinese carbon. Just what nipple people use and if it corrodes. It can happen to any rim out there pretty much. Aluminum carbon etc. How's that on topic?

  30. #6630
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    Quote Originally Posted by Tonggi View Post
    I haven't read a single post regarding Chinese carbon. Just what nipple people use and if it corrodes. It can happen to any rim out there pretty much. Aluminum carbon etc. How's that on topic?
    Reading comprehension fails you if that is what you have gleaned out of over 6,600 posts.

  31. #6631
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    (Cheap) Chinese Carbon Rims?

    Quote Originally Posted by tiretracks View Post
    Reading comprehension fails you if that is what you have gleaned out of over 6,600 posts.
    Obviously it was in reference to the last few pages, updates on carbon wheels, builds. Questions around it, new products etc.

    I mean come on dude, i was trying to be civil and joke around about being off topic. If you think about it, Why would I read a post from 4 years ago for updates?

    There's a small bit that my argument holds value since you can talk about building wheels elsewhere. Am I correct?

  32. #6632
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    I'm sure answers are back in there somewhere, but I'm overwhelmed.
    Questions I have are:
    1 Will my SRAM cassette work on what hubs? (SRAM 971) Everything I see on LB web sight says Shimano, and I just don't know if the hubs are the same.
    2 UD or 3K, what's stronger?
    3 Spokes?
    Bike is a Specialized Camber Aluminum, I'm hard on it but not into jumping much. I'm about 205# all up, but that's going down, honest.

  33. #6633
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    Quote Originally Posted by Bubblehead10mm View Post
    I'm sure answers are back in there somewhere, but I'm overwhelmed.
    Questions I have are:
    1 Will my SRAM cassette work on what hubs? (SRAM 971) Everything I see on LB web sight says Shimano, and I just don't know if the hubs are the same.
    2 UD or 3K, what's stronger?
    3 Spokes?
    Bike is a Specialized Camber Aluminum, I'm hard on it but not into jumping much. I'm about 205# all up, but that's going down, honest.
    1 - yes
    2 - its just a cosmetical thing. the finishes are called UD, 3k or 12k
    3 - yes, you need spokes. even on carbon wheels! (sorry, i would not recommend any spokes without knowing weight and riding style)
    Sokrates is dead, Galilei is dead, Newton is dead, Einstein is dead, Pantani is dead and i am feeling sick too.

  34. #6634
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    Re: (Cheap) Chinese Carbon Rims?

    Quote Originally Posted by Tonggi View Post
    Are having a biology discussion or carbon rims? Can you guys stay on topic? Any word on 29er 35mm oval shaped wheels coming out anytime soon? I think I remember seeing someone post this. I dont want to buy derby's. Its like getting 3 Chinese rims for 2 derby's which may be worth it in the long haul with their current t sale going on
    Tell me more about this oval shape 35mm rim and how it compares to the current rim shape on the lb website.

    Also: I've had runners tell me that tech t's, dry-fit fabric, etc, can cause nipple corrosion during long runs. Fwiw.
    Last edited by rfxc; 12-17-2014 at 06:00 AM.

  35. #6635
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    Known issue, magnesium nipple rings to act as sacrificial anode will solve this.

    Sent from my G3 using Tapatalk.
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    (Cheap) Chinese Carbon Rims?

    Quote Originally Posted by rfxc View Post
    Tell me more about this oval shape 35mm rim and how it compares to the current rim shape on the lb website.

    Also: I've had runners tell me that tech t's, dry-fit fabric, etc, can cause nipple corrosion during long runs. Fwiw.
    I'd also like to know. Only oval cf rims I know of are derby's and the 38 mm rims which may be overkill. In essence I wanna save and get Chinese since it's cheaper than derby's. 3 for the price of 2 but oval,warranty is nice. I have a set of Chinese 35 mm now and love them just wish they were oval. Aesthetic preference

  37. #6637
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    (Cheap) Chinese Carbon Rims?

    I've just built some 29er Nextie 35mm wide 28mm deep rims. I was hoping to save a little weight over my current hope hoops (flow ex) but after building them using comps and brass nipples they are pretty much like for like weight wise.

    I've not ridden them yet. I'm a tad disappointed with the weight as that was one of the reasons in building them but I'll see how they are on trails. Hopefully I'll notice a difference and the build was worthwhile.


    One thing I have noticed is the shimano ice tech rotors weigh a ton, think I'll be replacing them sooner or later



  38. #6638
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    Great, now we'll have 1000 posts from Meltingfeather debating whether that's abrasion vs corrosion.

    Quote Originally Posted by rfxc View Post
    Also: I've had runners tell me that tech t's, dry-fit fabric, etc, can cause nipple corrosion during long runs. Fwiw.

  39. #6639
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    MF "I've spelled it out a few times, and since I stopped taking you seriously after the 5th or 6th complete BS post I saw from you, I'm not going to waste my time (again).
    Since you know what galvanic corrosion looks like (you probably don't even understand why that's funny), have you ever wondered why this corrosion only exhibits inside the rim cavity? Or why galvanic corrosion is not a problem in the numerous other places on a bicycle where carbon and aluminum are in contact?"

    Because the inside of the rim is kept moist especially with frequent washing. Water with dissolved salts, (which almost all water has unless it is RO or distilled), is a catalyst because it eases the flow of electrons Also, it does not get used up since the oxygen comes from the air (so it is a true catalyst in this reaction) . The oxygen in water H2O is very tightly held, otherwise we would all be driving hydrogen powered cars. The oxygen in the air is O2 and is very available.

    MF"I know how it works, which is why it doesn't seem at all to be galvanic.
    It looks like straight attack on the unanodized aluminum, most likely by ammonia. IIRC ENVE even recommended or supplied Gorilla tape with their wheels. Gorilla is porous and allows diffusion of ammonia through it.
    The lack of consistency of this problem is another strong clue. Carbon rims have been in use on road bikes for many years, wet conditions, washing... everything you're trying to tie to galvanic... but without sealant containing ammonia. Don't know that I've heard of or seen a single instance of this on road bikes. Galvanic corrosion is something that happens every time the recipe is there... every time."

    All my nipples are DT and they are all anodized (the black and red ones in the pictures automatically disprove the non anodized theory). The recipe has many ingredients-every one of them has to be there and sometimes there can be one thing that prevents the recipe from working because it is an antagonist for something in the recipe. Or sometimes the ingredients come in the wrong order. Ask any woman who has had a pie crust fail or a souffle fall down. Hell, ask any of us homebrew sealant guys what happens if you put the PG with the Latex before mixing it with water.

    MF"Ammonia in this situation is a corrosive acid, not a catalyst."

    Ammonia is a strong base. The is exactly the kind of BS that you always belittle everyone else about. I learned ammonia was a base in either 6th or 7th grade-I don't remember which, but I do remember that ammonia is a base. Acids are, well, acids. Acids have low ph's less than 7 and bases have high ph's more than 7. Ammonia could be a catalyst since as you pointed out a catalyst is something that speeds a reaction but is not used up in the reaction. Guess what- Aluminum oxide is AL2O3. Ammonia is NH3. Since there is no Nitrogen or Hydrogen in the AL2O3 none of the ammonia is being used up or converted in the reaction. The reaction is aluminum combining with oxygen from the air. My thought is that the 3 hydrogens attached to the Nitrogen could aid in the flow of electrons just like the water does. But in that process neither the water nor the ammonia would be consumed. I am not even sure as you seem to be that the ammonia is even a catalyst or much of one. The water is certainly enough of a catalyst to get the job done. I will concede that the ammonia could be a catalyst but never that it is a corrosive acid.

    MF"Would it be totally unacceptable for you to keep your mouth shut when you don't know you're talking about?
    Due to your unfortunate combination of ignorance and prolific posting, you are a big part of the reason why there is confusion about the corrosion issue.
    "

    Where do I start? This is your motto/mantra is it not? Why don't you live by it!

    MF"I and a few others have provided the little good info on corrosion that has been posted."

    Citations needed; but little does seem to be the amount of good information you have provided.

    MF"Here's some cut-and-paste for you:
    "catalyst - a substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change."
    Reactants are not catalysts. Period.
    Keep posting ignorant crap and you will keep getting corrected.


    Still on that soap box I see-NH3 is still NH3 after all the nipples are turned to dust-you stand corrected again. And just in case you are going to say that the ammonia is somehow used up but not in the final products then please account for the molecules of nitrogen and hydrogen (and by the way if this works and we get a lot of free hydrogen out of the deal we are all going to be driving hydrogen powered cars next year)

    MF"I guess you don't understand that ammonia undergoes chemical reaction/change in this scenario?
    Why is that not surprising.
    Look at how much time is wasted because you're posting things you have no idea about.
    I think it's pretty obvious to anyone who reads the forum where you're coming from and hopefully they attribute the appropriate level of credibility (zero).
    The catalyst thing was just a convenient example of the type of thing you say all the time that is demonstrably false, as if you had said, "the earth is flat, so therefore..."
    And I'm the one who needs things spelled out? lol"


    Well do I have to explain to the world again that AL2O3 has no N or H? And please tell us about the changes ammonia goes through in this reaction. Pretty much everything you said was wrong and you just kept saying it which is what you keep accusing everyone else of.
    Full rigid SS, Hardtail SS, Hardtail Geared, Full Suspension Geared.

  40. #6640
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    (Cheap) Chinese Carbon Rims?

    Quote Originally Posted by J273 View Post
    I've just built some 29er Nextie 35mm wide 28mm deep rims. I was hoping to save a little weight over my current hope hoops (flow ex) but after building them using comps and brass nipples they are pretty much like for like weight wise.

    I've not ridden them yet. I'm a tad disappointed with the weight as that was one of the reasons in building them but I'll see how they are on trails. Hopefully I'll notice a difference and the build was worthwhile.


    One thing I have noticed is the shimano ice tech rotors weigh a ton, think I'll be replacing them sooner or later


    Sweet stumpy dude! I have the build on my evo stumpy 29er and I saved 180 grams just in the front. That's fully built with xtr rotors. But that's compared to stock wheels.

    Maybe weight wise it won't be much but wider rims as well as stiffer rim would help. Is the rim an oval shape from nextie?

  41. #6641
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    Corrosion

    Here is my experience…..maybe can help someone make a decision.

    Rims = LB
    Spokes = DT Swiss
    Nipples = Alum
    Rim tape = Stan’s
    Sealant = Stan’s’
    Location of bike = 4 Miles from the Ocean

    After about 1.5 years I pulled the rim tape off to inspect the nipples. Sure enough there was corrosion with a substantial amount of material missing from the nipples. Strange part is that some of the nipples were worse than others and some of the nipples had no corrosion at all!
    Had the nipples replaced with brass (reused the spokes).

    DZ

  42. #6642
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    After pondering this for several hours, I have a theory that seems to fit all the facts. If you don't want to read all the boring stuff just scroll down to the bottom to see what I believe is a logical explanation.

    First I have to say that this is just a theory and I can't prove it. It does seem to be able to explain all the believed facts though and I have tried to think of other explanations without success.

    What we think we know:
    1. Doesn't seem to affect road wheels.
    2. Even seems to affect Enve wheels which are molded holes and only resin not carbon is touching the nipples so the conductivity should be low.
    3. Seems to affect some wheels more than others and even some nipples more than others.
    4. Frequent washing or wet riding conditions seem to enhance the problem.
    5. Seems to attack the nipples from the very end and not so much where they are in contact with the rim.
    6. The type of rim strip/tape seems not to affect the problem much-reports with Bontrager, Stans Tape, and Gorilla Tape.

    I know that the general setup of the stainless spokes and aluminum nipples especially if in contact with carbon more or less becomes a weak battery with the Aluminum nipples being the anode because they have the highest galvanic response. But this should be a really weak battery and not really strong enough to break through the anodizing on the nipples. At lease not for many many years. It doesn't seem to break through the anodizing on road wheels. So I tried to picture the wheel as a unit and figure what is driving this. What is causing a massive buildup of electrons that are then oxidizing the tips of the nipples right through the somewhat resistant anodized coating. Then it hit me like a bolt of lightning (or the light bulb going off in your head). The brake disc being dragged on by the pads is a mini dynamo making millions of free electrons as it is ground on by the pads. Those electrons then negatively charging the hub which charges the spokes which charges the nipples. Then in the almost 100% relative humidity that is the inside of a rim that water has seeped into through the spoke holes, those electrons now have enough electrical potential (voltage) to break through the anodizing and facilitate the oxidation of the aluminum. The humidity combined with the higher electrical potential is all that is needed to seal the deal. As an added area to explore-I run metalic pads; I have to wonder if organic pads would generate the same amount of electrons.

    This explanation fits all the knowns: 1. Road bikes until recently don't have disc brakes and also, most road riders use their brakes way less than MTB riders. 2. Enve wheels should be practically immune since their nipple holes are molded. The resin on the surface of carbon products is a very good resister-not a perfect resister, but a good resistor. Enve wheels seem to still have the problem to about the same degree. 3. Some wheels are subjected to much more braking than others and also, some wheels might be relatively dry inside the rim. 4. Dry air is a fairly good resister, humid air is not. Also, it might only be a problem with metallic pads (I suspect that it would still happen with organic pads, but to a lesser extent). I personally brake hard for a few seconds at a time since I generally ride rolling curvey courses. This would be perfect to precipitate the reaction I am describing since the voltage would get very high for a short period of time. 5. The electrons would tend to congregate in the aluminum since it is the anode of the system and at the ends of the aluminum since all the electrons in the system repel each other more of them will congregate at the end. The parts of the nipples that are the furthest out will have the most free electrons. Some nipples are affected more than others since once the anodized coating on a nipple broke down, that particular nipple would be more susceptible and require a lower voltage to oxidize in the future. So as you ride along, light braking would provide enough voltage to further oxidize that nipple but not one on which the anodizing was intact. 6. The type of rim strip/tape is not relevant since the moisture is getting in by seeping between the nipple and the nipple seat during washing or wet riding.


    So my theory is that disc brake rotors become a dynamo that drives electrons thorough the wheel into the nipple ends and the moist environment in the rim allows easy oxidation. I would love to hear alternative theories that also address all the believed facts and any facts that would tend to make this theory not be viable.
    Full rigid SS, Hardtail SS, Hardtail Geared, Full Suspension Geared.

  43. #6643
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    Quote Originally Posted by yourdaguy View Post
    I would love to hear alternative theories
    I blame the North Koreans. If they can hack Sony, they can do anything.

  44. #6644
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    Your theory yourdaguy, makes a lot of sense. Very interesting indeed!
    Last edited by abelfonseca; 12-18-2014 at 03:29 PM.

  45. #6645
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    what wheels do you guys recommend for XC at 175 lbs?

    Hookless 30mm Width x23 5mm Depth Clincher 29er Carbon Wheelset Tubeless Ready | eBay

    Hookless 30mm Width 29er Carbon Mountain Wheelset Tubeless Compatible Am DH | eBay

    or something else? both of those say Weight: 1560+/-30g/pair excluding skewers. are there lighter sets? is that weight accurate?

    thanks.

  46. #6646
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    Rojo

    Nice looking orange spokes :-)

    Which model are they ?

    Thanks

  47. #6647
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    Light Bicycle 29 wheelset

    (Cheap) Chinese Carbon Rims?-1-dscn2481.jpg
    Attached Thumbnails Attached Thumbnails (Cheap) Chinese Carbon Rims?-1-dscn2485.jpg  

    (Cheap) Chinese Carbon Rims?-1-dscn2487.jpg  

    (Cheap) Chinese Carbon Rims?-1-dscn2488.jpg  

    Last edited by BOA; 12-31-2014 at 12:09 AM.

  48. #6648
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    (Cheap) Chinese Carbon Rims?

    ...
    Last edited by Girani2486; 02-15-2016 at 12:52 PM.

  49. #6649
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    Quote Originally Posted by Henrik83 View Post

    Is carbon-bicycle the same company or just a rip-off?
    They are apparently just a different seller selling the same rims. They appear to have a common manufacturer sourcing them. I bought from carbon bicycle and have no complaints.

  50. #6650
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    Quote Originally Posted by Henrik83 View Post
    38's or 35's.... 3mm for an extra 60gr in total. I don't like weight but I sure would like som wide rims. What is the main advantage with the extra 3mm? IMO the extra weight should be more of an disadvantage then the advantage from the extra 3mm. What am I missing?
    The differences are 38/31.6mm rims have a thicker hookless bead. Each side is 3.2mm thick. It should be able to handle more rim hit intensity. And the inside dimension is 31.6mm.
    35/30mm rims have 2.5mm hookless beads and an inside dim of 30mm.
    No probs with the CB 35/30mm rim I built for a rear.

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