# Niobium 30 rims - what's the big deal?



## topflightpro (Nov 3, 2004)

I was talking with Ligero about a wheel build and he suggested Niobium 30 rims. 

I've seen a lot of people on this board suggest those rims or write how they want those rims. For those of you who have them, what do you like about them?


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## ergott (Feb 26, 2006)

Good balance of weight, semi aero profile, durability, and price. The rim is also pretty stiff so you can use a lower spoke count than a similar build with box section rim.


-Eric


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## android (Nov 20, 2007)

Only slightly off topic....
Have you done any builds with what is called the IRD Cadence and Cadence VSR O/C rims?
They're also Nio, but more of a regular profile, and much lighter than Open Pros.

I've got some old DA 8spd hubs that would be a good candidate for rebuilding on something like this.


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## prschatt (Aug 19, 2007)

How are their 27mm rims?


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## ergott (Feb 26, 2006)

android said:


> Only slightly off topic....
> Have you done any builds with what is called the IRD Cadence and Cadence VSR O/C rims?
> They're also Nio, but more of a regular profile, and much lighter than Open Pros.
> 
> I've got some old DA 8spd hubs that would be a good candidate for rebuilding on something like this.


I've seen some corrosion issues with the eyelets. There is a Kinlin version that is called the Nbr. It's the same rim with drilling for internal nipples so durability should be much better.

-Eric


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## ergott (Feb 26, 2006)

prschatt said:


> How are their 27mm rims?



I've been using the 27mm more often now. It's still a semi aero profile and weighs more like 435g whereas the 30mm is 470-475g. I've also noticed that they are building up more round when the tension is even. Functionally, they both work well, but I prefer a rim that is within my building specs when the tension is even. Maybe the next batch that comes in will be more consistent as they were not too long ago.

-Eric


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## backinthesaddle (Nov 22, 2006)

android said:


> Only slightly off topic....
> Have you done any builds with what is called the IRD Cadence and Cadence VSR O/C rims?
> They're also Nio, but more of a regular profile, and much lighter than Open Pros.
> 
> I've got some old DA 8spd hubs that would be a good candidate for rebuilding on something like this.


I built a set of the Cadence/Cadence VSR OC hoops on White hubs with CX-Ray spokes. They came out light (1405), stiff, true and round. They are bulletproof. The rims are very nice. I must have gotten the end of a batch run though, as they were about 20 grams heavier (each) than advertised. Still, very nice hoops and a good option versus OPs.


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## ghostzapper2007 (May 22, 2007)

ergott said:


> I've been using the 27mm more often now. It's still a semi aero profile and weighs more like 435g whereas the 30mm is 470-475g. I've also noticed that they are building up more round when the tension is even. Functionally, they both work well, but I prefer a rim that is within my building specs when the tension is even. Maybe the next batch that comes in will be more consistent as they were not too long ago.
> 
> -Eric


Since almost all rims from any manufacturer are not 100% perfectly round before being built up, what limits do you set as to whether you think a rim is actually buildable versus looking at the rim and saying , "NO, I'm returning this to the supplier." For example, how out of round would a new unbuilt 700c rim have to be before you refused to build a wheel with it, since my understanding is that most builders will work with a slighty out of round rim to begin with and make it more round during the build by altering spoke tensions to bring it more into round/true? Thanks


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## ergott (Feb 26, 2006)

ghostzapper2007 said:


> Since almost all rims from any manufacturer are not 100% perfectly round before being built up, what limits do you set as to whether you think a rim is actually buildable versus looking at the rim and saying , "NO, I'm returning this to the supplier." For example, how out of round would a new unbuilt 700c rim have to be before you refused to build a wheel with it, since my understanding is that most builders will work with a slighty out of round rim to begin with and make it more round during the build by altering spoke tensions to bring it more into round/true? Thanks


I take 4 diameter measurements of each rim. I prefer to have a standard deviation of under 0.5, although I have gotten some rims up to SD of .9 and they worked out. What I notice about the 30mm is that they have a high spot in the same place on every rim. I seem that when the extrusion is turned, there is an imperfection that ends up there. They turn out ok and you would never notice it riding them, but I seen it on the truing stand. With the 27mm, I have been getting, the rims are 35-40g lighter and I don't think the aerodynamics will be that different.

-Eric


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## cpark (Oct 13, 2004)

topflightpro said:


> I was talking with Ligero about a wheel build and he suggested Niobium 30 rims.
> 
> I've seen a lot of people on this board suggest those rims or write how they want those rims. For those of you who have them, what do you like about them?


I think that the people(including myself) are making a big deal out of it for the following reasons.
It's aero, light, durable, inexpensive and looks good.

That's pretty hard to find all that in a single rim....


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## ghostzapper2007 (May 22, 2007)

ergott said:


> I take 4 diameter measurements of each rim. I prefer to have a standard deviation of under 0.5, although I have gotten some rims up to SD of .9 and they worked out. What I notice about the 30mm is that they have a high spot in the same place on every rim. I seem that when the extrusion is turned, there is an imperfection that ends up there. They turn out ok and you would never notice it riding them, but I seen it on the truing stand. With the 27mm, I have been getting, the rims are 35-40g lighter and I don't think the aerodynamics will be that different.
> 
> -Eric


Thanks, very good info.


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## rruff (Feb 28, 2006)

ergott said:


> I prefer to have a standard deviation of under 0.5, although I have gotten some rims up to SD of .9 and they worked out.


I had my very first Nio30 reject yesterday... just couldn't get it under .015" without a pretty large tension variation. Usually it's under that with no variation at all.

What do you use to measure the rim? It sucks to have to build it first...


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## ergott (Feb 26, 2006)

rruff said:


> I had my very first Nio30 reject yesterday... just couldn't get it under .015" without a pretty large tension variation. Usually it's under that with no variation at all.
> 
> What do you use to measure the rim? It sucks to have to build it first...


I have the Wheelsmith spoke rods. I think that I should measure them in more places around the rim if I suspect there might be roundness issues. The bump would fit in between the 4 places I measure now.

-Eric


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## henlin (Aug 7, 2006)

ergott said:


> I've been using the 27mm more often now. It's still a semi aero profile and weighs more like 435g whereas the 30mm is 470-475g.
> 
> -Eric


Along the same lines of thinking--are there perceptible aero differences between 27mm and 30mm rims? Aero gurus feel free to chime in here


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## steel515 (Sep 6, 2004)

*27mm rims*



ergott said:


> I've been using the 27mm more often now. It's still a semi aero profile and weighs more like 435g whereas the 30mm is 470-475g. I've also noticed that they are building up more round when the tension is even. Functionally, they both work well, but I prefer a rim that is within my building specs when the tension is even. Maybe the next batch that comes in will be more consistent as they were not too long ago.
> 
> -Eric


how does ird 27mm compare to Velocity Aero, Fusion, Open Pro for strength/roundness.


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## rruff (Feb 28, 2006)

ergott said:


> I have the Wheelsmith spoke rods. I think that I should measure them in more places around the rim if I suspect there might be roundness issues. The bump would fit in between the 4 places I measure now.


Just had an idea. Take a long piece of metal and attach a couple of cartridge bearings to one end... spaced a few inches apart so the rim is "located" (ie resting) between them... and attach a dial gauge to the other end that rests on the edge of the rim. This way the rim can be spun around and the radial runout measured to extreme accuracy. Of course it would be better to measure from the center of the rim rather than from one side to the next... but that would be a lot more difficult.


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## rruff (Feb 28, 2006)

henlin said:


> Along the same lines of thinking--are there perceptible aero differences between 27mm and 30mm rims? Aero gurus feel free to chime in here


If by perceptible you mean you can "feel" it, then no way. If you mean that there is a speed difference that could be measured, then yes... but not a lot. The Nio30 is stiffer as well as being heavier than the 27, so that is also a consideration.


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## backinthesaddle (Nov 22, 2006)

rruff said:


> If by perceptible you mean you can "feel" it, then no way. If you mean that there is a speed difference that could be measured, then yes... but not a lot. The Nio30 is stiffer as well as being heavier than the 27, so that is also a consideration.


I built my PT SL on a Nio30 hoop (IRD Cadence aero). 32hole hoop, 3x with CX-Ray spokes. It's a damn stiff wheel. The rim weighed 460 out of the box.


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## Forrest Root (Dec 22, 2006)

ergott said:


> I have the Wheelsmith spoke rods. I think that I should measure them in more places around the rim if I suspect there might be roundness issues. The bump would fit in between the 4 places I measure now.
> 
> -Eric


You're doing it all wrong. You need one of the things below. We've been using them with great success to measure coordinates to micron precision or better. Measuring roundness of a rim would be a walk in the park.

BTW, why did you choose using std dev over rms?

You'd really be doing your customers a disservice if you didn't step your game up and build to much tighter tolerances.


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## Forrest Root (Dec 22, 2006)

rruff said:


> Just had an idea. Take a long piece of metal and attach a couple of cartridge bearings to one end... spaced a few inches apart so the rim is "located" (ie resting) between them... and attach a dial gauge to the other end that rests on the edge of the rim. This way the rim can be spun around and the radial runout measured to extreme accuracy. Of course it would be better to measure from the center of the rim rather than from one side to the next... but that would be a lot more difficult.


Amateurs. Rank amateurs. I've already shown Ergott the Path. Plus, with the kit that I showed him, he'd be able to optimally position his work, in space, to minimize his energy expenditure while increasing--or decreasing, if needed--the moments he applies to fasteners and adjustments on the wheels.

Ergo, ipso facto, Q.E.D.


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## cpark (Oct 13, 2004)

henlin said:


> Along the same lines of thinking--are there perceptible aero differences between 27mm and 30mm rims? Aero gurus feel free to chime in here


Not an aero guru here but did sleep at the Holiday Inn. 
I did read somewhere in my Zipp catelog that the measurable aero benefit kicks at a rim height of 42mm or more.
I'm think the number of spoke and its shape probably have huge affect as well...


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## Forrest Root (Dec 22, 2006)

cpark said:


> NI did read somewhere in my Zipp catelog that the measurable aero benefit kicks at a rim height of 42mm or more.


Zipp can say all matter of things that make no sense. Measurable? With what? You can measure damned near anything with the right tool. Did Zipp say at what speed or at what dimple depth the positive aspects of dimpling become a factor? How about those dimples on hubs?

Catalogs and white papers are lousy places to hunt for objective information.


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## Kerry Irons (Feb 25, 2002)

*Kicking in*



cpark said:


> I did read somewhere in my Zipp catelog that the measurable aero benefit kicks at a rim height of 42mm or more.


You see these kinds of comments all the time, but they really defy common sense. As the rim profile gets higher, aero drag is reduced and sidewind sensitivity goes up. There is not a "knee in the curve" that would be noticeable in any way. To suggest that a 40 mm rim would be "slow" and a 44 mm rim would be "fast" (aerodynamics just "kicked in," don't you know?) is preposterous on the face of it.


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## cpark (Oct 13, 2004)

Forrest Root said:


> Zipp can say all matter of things that make no sense. Measurable? With what? You can measure damned near anything with the right tool. Did Zipp say at what speed or at what dimple depth the positive aspects of dimpling become a factor? How about those dimples on hubs?
> 
> Catalogs and white papers are lousy places to hunt for objective information.


With those dimpled hubs, I'm about to break the hour record....


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## rruff (Feb 28, 2006)

cpark said:


> I did read somewhere in my Zipp catelog that the measurable aero benefit kicks at a rim height of 42mm or more.


One of my favorite aero misquotes! Zipp said something sort of like that a few years ago when their 38mm 303 was the shortest aero rim they sold. What they really meant is that it doesn't make any sense to do the toroidal shape with a rim less than 38mm tall. But the aero benefits of deeper rims starts in the low 20mm range at least, and the curve is steepest there with diminishing returns as you go deeper.


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## ergott (Feb 26, 2006)

Forrest Root said:


> You're doing it all wrong. snipped.



I don't even want to know what you do with that thing;-)

Rms?

-Eric


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## dwaharvey (Jun 1, 2006)

RMS = root mean square. For a set of quantities x_i, RMS(x) = sqrt ( (1 / n) * Sum_i ( x_i ^ 2 ) )

I'm not sure if the poster was being flippant because in your application the RMS is the same thing as the standard deviation which is what you are using (let x_i be the difference between the rim diameter in a particular location and the average rim diameter....and then you have the formula for the standard deviation).


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## jolnar (Nov 6, 2007)

I had a IRD offset rear rim 32hole built to a DT Swiss hub and I cracked out all the drive side eyelets. LBS built it up, I'm 210lbs. and I climb out of the saddle some. I was told by a different LBS that I shouldn't ride single eyelet rims with my weight.


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## cmg (Oct 27, 2004)

thought of using a heavier rim on the rear for that reason. A noibium 30 or velocity aerohead OC for the rear and the IRD cadence in the front. as long as their black they'll look similar. might be the way to go.


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