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PostPosted: Tue Aug 27, 2013 12:06 am 
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Posts: 170
Let's assume there is a tangle benifit to balancing our wheels. My method of balancing carbon tubular rims is by injecting a "balancing agent" (sand and glue) into the spoke holes opposite the valve. That may help you with what I would like to do to a disc or trispoke.

Maybe some familiar with the construction of Discs and Trispoke wheels can help me think about a method to balance.

The only option I have thought about is drilling a 3mm hole into the rim bed opposite the valve for an injection site. Here are some concerns I can come up with:
-The rim is filled with a foam, which would not allow the mixture to rest properly on the rim bed while it hardends.
-Structural integrity of the rim will be compromised by drilling. But, I don't think drilling would cause propblems because rims are drilled much larger than 3mm for spokes and nipple installation of standard hoops, but maybe discs and trispokes are made differently and therefore cannot handle being drilled.

Also, can anyone discribe to me the cross section of a Trispoke rim?

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PostPosted: Tue Aug 27, 2013 12:33 am 
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Location: Los Angeles / Glendale, California
Another method of 'balancing' would be to find some lead tape, it's less invasive than "injecting" your concoction into the wheel itself.

Go to your local tennis or golf shop, they'll usually have weighted tape available, or you can find this at a hardware store.

Figure out how much weight you need to add with an easily sort-able weight, such as 'dimes' if you are in the US or the smallest sized currency in your country. Once you know how many (x) are needed, then figure out how much lead tape is equivalent. This can be done in one cut: weigh the entire roll, calculate the grams per unit of length. See how many grams you need, cut that appropriate length. Apply the lead tape to the tire or tube track of the wheel. Done.

The benefit: it can be removed easily, adjusted, etc:. You won't damage the wheel at all, which is nice in case you ever think of selling it.


No injections. We have enough trouble with injections in cycling. :lol:

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Posted: Tue Aug 27, 2013 12:33 am 


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PostPosted: Tue Aug 27, 2013 1:29 am 
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Your non-invasive idea had me doing a bit more research... any opinions on DynaBeads? Here some people discuss them in motorized bicycles. http://motorbicycling.com/showthread.php?t=34612

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PostPosted: Tue Aug 27, 2013 10:23 pm 
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prendrefeu,
I tried the lead tape, $6 for 18gm, I ended up using 12gm to balance a HED 3c. I used two layers at 13mm x 52cm, centered opposite the valve and down the middle of the rim-bed. Though the wheel is not perfectly round it is well balanced. There is plenty of carbon exposed on both sides of the tape so I don't forsee any issues when I glue the tub. This is now my preffered method of balancing. Thanks.

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PostPosted: Wed Aug 28, 2013 3:23 am 
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Discussing adding weight seems like a sin on WW. :)
Makes me curious though, I thought a lot of rims these days are already balanced, i.e. extra weight opposite the valve hole. Is there any way to tell whether a rim is or isn't? Some it's clear in the marketing, others it seems like they are but hard to find out.
Edit: I'm also curious about the lead tape method, as far as how truly "balanced" the wheel is, since the weight of the tape is spread out across a much larger area than the stem weight.


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PostPosted: Wed Aug 28, 2013 7:11 am 
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It is a sin. :evil:

You can tell if it is off balance by listening to it while it spins by listening to it (the sound would come in 'waves' with each rotation) or by spinning the wheel while the bike is on/in the repair stand. Spin the wheel vigorously: if the bike bobs up and down a bit from the motion of the wheel, the wheel has poor balance. A balanced wheel spun vigorously will not move the rest of the bike.

Does it matter? Some people are more particular about this than others. Supposedly, performance wise, it makes a difference. I can see the reasoning there.

As for wheels already being pre-balanced: not necessarily. There is no way to predict the length of the valve a person will use, so how would a mfg properly balance the wheel in anticipation? You, however, the user, tend to stick to the same length/type of valve... so you've then added in a constant weight, you can then balance from there. You can also be lucky by happening upon the right wheel + valve combo which results in a balanced wheel.

For the 'spreading out' of weight: it will be fine.

You could also, theoretically, take that same determined weight that you need to balance opposite the valve and apply it to the other 2 quadrants of the wheel, making an overall more balanced wheel. But really, that's just heresy.

I just simply helped natefontaine with a better solution to what he wants to achieve. I have no strong opinion on whether a person should or needs to balance their wheels.

My current wheels do not need balancing, so I did not need to add weight.

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PostPosted: Wed Aug 28, 2013 8:27 am 
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natefontaine wrote:
There is plenty of carbon exposed on both sides of the tape so I don't forsee any issues when I glue the tub.
Won't you now have a lump in the tub?

And why not balance it after the tub is fitted, tubs aren't perfectly balanced either (inner tube valve?)


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Posted: Wed Aug 28, 2013 8:27 am 


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PostPosted: Wed Aug 28, 2013 9:22 am 
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Yeah the balancing happens after the tire is fitted -> determine weight needed -> remove tire/tube, apply weight -> reinstall tire/tube.

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