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  1. #1
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    New question here. Unholey carbon rim beds?

    *disclaimer- I don't know shat when it comes to wheel building, but do know how to listen and learn.

    UST is a fairy well know set of specs as it applies to rim (and tire) shape as far as I can tell and was started by Mavic in the 90's, blah blah blah.
    One component of it is a rim bed devoid of holes except for the valve stem, duh.

    In the burgeoning world of carbon rim and wheel producers, a few have offered up hoop/wheel builds without holes in the rim bed, a la UST.

    It is obvious what a PITA it would be on initial assembly to be dragging 24-32 nipples baited with a ferrous bit with a magnet to the outer rim hole and then feeding said nipple through the hole and threading and partially tensioning it onto a preposition-ed spoke from the outside would be. Thinking of it exhausts my patience. However Carbonfan for example only up-charges $10/rim to do it this way.

    However, and this is where I'm coming at it from, and that is as an end consumers perspective. Yes, I've broken several spokes (mostly on a new OEM Bontrager asymmetrical aluminum 29'er wheels in 2012- like 5x...) None since int he last 6 years with aftermarket wheels- AC and WTB- go figure LOL.

    So if one were to break a spoke only occasionally and have to "deal with" a rim bed sans holes in replacing a spoke and nipple, just how big a deal would it be? An extra 30 minutes max? Again, I've never done it, so I'm coming at this from a perspective of ignorant bliss I can see that if one were to do the UST thing that straight pulls may have an advantage???? A vertically in-compliant positioned J spoke might be more difficult I guess.

    And as to regarding why NOT have the wheel mfg drill the drill the rim bed with holes ( to facilitate their ease of assembly AND subsequent repair by whomever), I can think of a few reasons.

    First is structural. Holes can't help with rim integrity. These things are built light enough especially on the XC end of things. And some pics of these drilled rim beds look sorta random or imprecise in placement from what I can see. I'm sure it's all done CNC or whatever, but especially on some asymmetric it looks like butt with offset bed holes too.

    Second is taping. Yes, I've taped rims many a times and rarely, tape is an issue. Follow the plethora of threads on tape types and their failures... Credit to Bontrager years ago and Enve recently for at least offering a less "band aid" approach to hole coverage with their plastic strips/liners.

    Lastly, UST beds look cool. And that's why we all do all this, right? Yea baby, if you could see my rim bed, it has no holes LOL

    Thanks if interested enough to read this far and feel free to flame, and/or educate me! I'm not part of the real world of wheel building or even repairing, and truly do like to understand why what's done!

  2. #2
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    I have one of those rims, and I laced them myself with J-bend spokes.
    With some practice, in 30 minutes you can almost lace the hole wheel, not including bring it up to tension or true, just lacing it.
    So, without practice, using a magnet and a small bolt, one would take maybe 5min to replace the nipple and spoke. If you lose the nipple inside the rim that's more 5 to 15 minutes to get the hang of how to take it out, subsequent tries will only take 15 to 30 seconds, don't ask me how I know .

  3. #3
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    Replacing a nipple doesn't seem like a big deal. The most tedious part will still be re-taping the rim. I considered this on my last wheelset, but I'm a weight weenie and the holes are lighter than having no tape

  4. #4
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    Although it's a bit tedious to use the magnet it does avoid the taping and the weight of the tape. But, the tape does add a not insignificant thickness to the rim diameter and that can affect inflating of the tire and burp resistance. Ideally these rims without internal spoke holes would compensate for the missing tape by having a slightly larger diameter, but that seams unlikely. This is obviously not a huge issue as tires very quite a bit in size between brands and models and even from tire to tire, but very loose fitting tires are a problem for efficient tubeless setup.

  5. #5
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    Unholey carbon rim beds?

    Good points all
    Regarding inner rim diameter and bead fit, yea that seems to be a brand thing crap shoot. Iíve been hooked on how Schwalbes fit my ACs.
    However the Stans tape Iím currently using is wide enough to go into the bead socket, rarely has been loosened with a tire change. Before that, Iíd taped only covering the rim bed concavity and a couple time pulled it up unseating a tire bead.
    While retaping isnít a big deal, I see it as a bit of a weak link relative to a UST bed. So IMO, why go there?

    Now if I were building wheels or paying someone to do it all day long, of course Iíd prefer the access holes to be there for build time efficiency.
    Are there any other concerns with unholy beds? ( boy that sounded wrong. After all, we are talking going bareback with our rims and tires &#129315
    Is the nipples subjected to much more spoke/nipple wrench trauma/ deforming assembling this way as opposed to (my presuming) most of the threading being done from the inside with holes beds??. My current AC aluminum nipples are pretty soft and boogered up from routine trueing.


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  6. #6
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    Unholey carbon rim beds?



    Hereís a pic of a recent forum members build that seem great overall. However note how close three out of four holes near the bar code are to the bead hump. From what I can see, unless one were to tape up over the hump, there would be scant mms between tape edge and bead during dismounting. At least with a symmetrical rim the holes would probably all be lined up in the center, right?
    Not being critical, just curious about practical ramifications.


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  7. #7
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    The nipples don't get more stress than being used with a normal rim.
    But don't use aluminum nipples with carbon rims, unless you want to relace the entire wheel in the near future. It really isn't worth it just to save 20g.
    When taping rims, I always tape wall to wall, and if I can, 2mm or 3mm up the wall. This way I know for sure that there won't be any air leaks, and that the tape will stay in place when removing tires. But I know that's unthinkable for some people.

  8. #8
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    I ordered my most recent set of rims from Light Bicycle without holes in the rim bed and couldn't be happier. A very good local wheel builder built them up for me (extra $50 per wheel for the fishing, he said he tried to use a vacuum but had to use a magnet).

    I am very happy. I've swapped rear tires 5 times in the last 3 months and it's been so nice knowing that I wouldn't have an issue due to rim tape. For instance I was on a road trip in moab, and blew up a rear tire (two big pinch flats in it and a few thorn punctures) and it was really nice being able to replace the tire at the house and not have to worry. I've always hated and had problems with rim tape, especially on carbon rims.

    Ever since I switched to carbon rims, I've had fewer spoke and nipple issues. I think it's a combination of the wheel builds being tighter, the wheel flexing less leading to less chance for tension loss, and the rims not getting bent all the time. I've been using aluminum nipples in my carbon rims for about 6 years now. Haven't had any issue worth mentioning with the combination.

    10/10 would do it again. Don't care at all that a few years down the line it might make replacing a nipple harder, assuming the rims even last that long anyway I'll be happy.

  9. #9
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    Quote Originally Posted by Aglo View Post
    But don't use aluminum nipples with carbon rims, unless you want to relace the entire wheel in the near future. It really isn't worth it just to save 20g.
    Que? Incidentally, the difference is closer to 45g over the wheelset for a 32H/32H configuration.

  10. #10
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    Quote Originally Posted by alexdi View Post
    Que? Incidentally, the difference is closer to 45g over the wheelset for a 32H/32H configuration.
    I've had two different carbon wheels with corroded aluminum nipples that had to be replaced with brass. A light bicycle with Sapim nipples and an Ibis with Squorx nipples.
    Its been said here it has to do with the conductivity of the carbon and aluminum interface. I don't understand it but I'm never using aluminum nipples again in carbon wheels again.

  11. #11
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    Quote Originally Posted by ac1000 View Post
    I don't understand it but I'm never using aluminum nipples again in carbon wheels again.
    Interesting. That may be the right decision for you. Do check your rim tape, though. Some tubeless sealants will corrode alloy nipples if the tape is permeable. As to galvanic corrosion, it shouldn't happen if the nipples are lubricated and well-anodised. The risk is likewise lower for folks who ride in the dry.

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