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PostPosted: Wed Feb 13, 2013 8:57 pm 
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Joined: Mon Dec 17, 2012 2:35 pm
Posts: 2
So a dilemma I need help with-

My current powertap pro+ is laced to a very old open pro rim. Pretty sure this is quite corroded and going to die soon so I want to build it into a new rim. It's 32h so should I go open pro again or is there something similar that would be better? It needs to be clincher as I use this wheel on the turbo too but if there is an opportunity to lighten it up I dont mind spending a bit extra use will be rainy days and turbos.

I WAS thinking about getting a quarq so that I could get some nice tubular wheels too but have been warned off and can't afford an SRM and new wheels so next option is a G3 built into a tubular rim. Im happy to build myself - not that experienced but if I mess it up i will send it to someone who is. I am 67kg and live in Devon so although heart says deem carbon rims head says get the lightest setup you can find. Is it possible to build a decent weight stiff set from a G3?


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PostPosted: Wed Feb 13, 2013 9:08 pm 
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Joined: Wed Feb 13, 2013 6:57 pm
Posts: 1
Greetings.

I have a friend's RS80 and I am trying to figure out where to place it
on Park Tool's tension chart. The wheel has steel bladed spokes which
measure 1.5 on narrow and 2.0 on the wide bladed side. Other than a
1.3 x 2.1, there is nothing close to what I measured. Looking at the
chart I saw that changes on the narrow side have greater impact
than those on the wide side and I tried to work something out
with that.

For example

A 1.4/2.3 spoke reads 117kg at "20", while a 1.4/2.6 reads 103kg.
That is around 7% kg decrease for every additional mm and a +1
on the chart reading (0,33 for every mm) to get as close to the
117kg as possible (115kg).

A 1.2/2.6 spoke reads 144kg at "20", while 1.4/2.6 reads 103kg.
That is around 19% decrease for every additional mm and a +3
on the chart reading (1.5 for every mm) to get the same kg.

Let's say that I aim at 131kg which is number 19 on the chart for 1.3/2.1.
Based on the above, I guesstimate that 19 for the 1.5/2.0 spoke would be
around 90kg and I should be aiming at 21-22 to get the desired kg.

Does the above make any sense? If not, has anyone here worked with RS80
before so he can provide me with the magic chart numbers in order to
be between the Shimano's 100-143kg recommendation?

Thank you.


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Posted: Wed Feb 13, 2013 9:08 pm 


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PostPosted: Wed Feb 13, 2013 9:56 pm 
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Location: Glermsford, Suffolk U.K
Kavitor Klabs e.t.c the reason why more spoke tension helped in this case is not that increasing spoke tension imcrease lateral stiffness - IT DOES NOT DO ANY SUCH THING!!!!! Tension cannot increase the stiffness of the rim or the spokes, these are material properites determined by profile of the rim or spoke and the materials microstructure.

However increasing DS tension will increase NDS tension to when the high torque is being applied tot he rear wheel in a sprint say when the rim deflect it will have to deflect more to cause the NDs spokes to go slack. Once the NDS spokes (only some of them will go slack in a sprint and it will be the ones cloesest to the ground I think) the wheel lateral stiffness drops as these spokes are no longer holding the rim.

This is a different effect to saying spoke tension increaes wheel stiffness.

@Bearley. I use the Velocity A23 in builds quite alot and keep these in stock in most drillings. This rim has an ERD of 602mm. Give me the dimensions of you hub (or tell me what it is) and I can tell you what spokes lengths you need may be your existing spokes will be O.K. What spoke lengths do you have?

@T1mbro The velocity A23 is a good alternative to the Open Pro but has no eyelets (this not a problem though). If you want a rim that is 19mm wide then the Ambrosi Excellight is a good option as is the DT Swiss RR465. I personally think the RR465 is the best rim out of the lot, it is such a nice rim to build with and one of my favourites.
The Open Pro is the lightest rim of all the ones I have mentioned, it also the cheapest and it perfectly useable rim. I do not think they are the most durable but they are a bit lighter.

Eaglos, Anyone who uses the TN-1 has faced these issues. You have to use the TM-1 differently in these case. Decide by feel when the spokes are tensioned sufficently and then measure the deflection. You then have a deflection measurement to use to ensure the other spokes DS are evenly tensioned. NDS tension should also be even but the exact value will determined by getting the wheel dished.

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PostPosted: Wed Feb 13, 2013 10:47 pm 
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Joined: Sun Sep 21, 2008 9:07 pm
Posts: 966
Location: Slovenia---that forest land
KLabs: one rim cracked becouse i get 150kg on it. But if you get on xr200 over 120kg you can see deforming of rim where nipples are. That can be seen on black rims quickly- white colour( wich was test wheelset with 140kg on ds) dont show any deformation. maby becouse of extra powdercoating (white rims are heavier too).

When DS spokes goes up with tension also NDS and this is most important as bm0p700f says.
After all if we have same components wheel with higher tension will be better in sprint ...

I am waiting to build with Bartime hubs and see the results

Has anyone info for Wheelfanatyk tensiometer and mavic R2R spokes? I dont thrust TN1 here becouse for sapim cx ray must unwind screw for 5 rounds to get correct result (For Sapim Laser or Race it is set as i get it).

Also what do you think about home calibration tool - 150kg hang scale with spoke tensioned on 120kg?
Hope you understand what i have in mind

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PostPosted: Wed Feb 13, 2013 11:18 pm 
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I know what you mean about the XR-200 deforming (I limit the tension to 1150N max). I use a TM-1 but with CX-ray spokes I have decided now what deflection I look for and ignore the chart. I will have to get the Sapim/Horzan tenion gauge next as that looks a better bet for accurate measurment.

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PostPosted: Thu Feb 14, 2013 2:41 am 
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Joined: Tue Nov 11, 2003 9:47 pm
Posts: 1647
Location: Santa Cruz, California, USA
Kavitator- check this tensiometer calibration rig out: http://www.youtube.com/watch?feature=pl ... gsz7l1GWoI

I'm going to build one when I get a chance. The scale (I got the same one for $50 on amazon) is spec'd for +- .6kg.
I don't have a spoke threading machine and don't feel like I need one yet so I will machine a "flange" for the j-bend.

As far as more tension stiffening the wheel, sure, if the NDS spokes were loose enough to (momentarily) go slack. Beyond that if Rinard's results are correct, it should not make a difference. Of course he could have made a mistake or we could be not understanding what "slack" is in this case.


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PostPosted: Thu Feb 14, 2013 10:31 am 
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Joined: Fri Jan 28, 2005 11:51 am
Posts: 250
Location: arezzo (italy)
this is my new chinise 20 mm carbon rim for tubular, which is the best nipples can I use with this rims?

Image
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PostPosted: Thu Feb 14, 2013 1:36 pm 
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Joined: Tue Feb 05, 2013 2:46 pm
Posts: 63
eric wrote:
Of course he could have made a mistake (Dinard) or we could be not understanding what "slack" is in this case.



Bold mine.

Seems to me much of this rim stiffness debate is verbal semantics. To definitively state the rim functions independently of the spokes is not valid IMO. The wheel is a dynamic unit.. each component part of a system interdependent of the sum of the components.

The written wheel theory pales in comparison to real world data. I find some very interesting observations on these pages... those citing actual experiences building/testing the wheel/s the reason I came to read along here.

This internet is full of bike wheel 'nonsense'. It's fine to model the workings of a bike wheel on the computer.. but some of the conclusions assumed lack the sweat spent to make these wheels DURABLE & weight efficient in the real world.


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PostPosted: Thu Feb 14, 2013 3:00 pm 
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Joined: Wed Dec 01, 2010 4:29 am
Posts: 335
WinterRider wrote:
eric wrote:
Of course he could have made a mistake (Dinard) or we could be not understanding what "slack" is in this case.

Bold mine.

Seems to me much of this rim stiffness debate is verbal semantics. To definitively state the rim functions independently of the spokes is not valid IMO. The wheel is a dynamic unit.. each component part of a system interdependent of the sum of the components.
The written wheel theory pales in comparison to real world data. I find some very interesting observations on these pages... those citing actual experiences building/testing the wheel/s the reason I came to read along here.
This internet is full of bike wheel 'nonsense'. It's fine to model the workings of a bike wheel on the computer.. but some of the conclusions assumed lack the sweat spent to make these wheels DURABLE & weight efficient in the real world.

Hi WinterRider, everything is good :-)

In kavitator's circumstance NDS spoke tension appears to have been an issue (through sprinting/pedal torque effects) and by increasing DS and NDS spoke tension this increased lateral stiffness when the wheel encountered sprinting/pedal torque effects. Unfortunately the rim could not completely handle the 140kgf DS spoke tension :-)

I believe that Bracing Angle is important to lateral stiffness and better Bracing Angle (like those of the front wheel) allow DS spoke tension to be reduced and better NDS spoke tension. 2x/3x/4x lacings provide better control of sprinting/pedal torque effects, and re the aspect of DS/NDS spoke tension, the 2:1 lacings provide nearly equal DS/NDS spoke tensions with excellent NDS Bracing Angle and as such good Lateral Stiffness. Although 2:1 lacing allows better Lateral Stiffness (through better Bracing Angle and more even DS/NDS Spoke tension), the Rim will provide the real Lateral and Radial Stiffness.

Wheel stiffness. logically, is determined by the Rim, Spokes, Spoke Lacing, and Hub. That is quite a broad statement so what does this actually mean (hope this is correct) ...

1. The Rim will provide the real Lateral and Radial Stiffness (ie a flexy rim will always be flexy regardless of spoke tension)
2. The Hub needs to support good DS/NDS Bracing Angle and Spoke Lacings that help control sprinting/pedal and Disc Brake (if used) torque effects
3. Spokes need to be stiff and strong and able to endure the tension/detension cycle which occurs as a result of torque effects
4. Rim widths and Tyres ... that's another matter :-)


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PostPosted: Thu Feb 14, 2013 3:23 pm 
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Location: Santa Cruz, California, USA
If you had read the article you'd know that Rinard did not use a computer model and was not testing "rim stiffness" in isolation. He was testing an actual wheel. That's "real world".

Since that work he's become well respected in the industry. He's been a lead engineer at Trek and now at Cervelo. I would not say that means everything he's written is gospel but clearly he knows his engineering.

My "real world" experience has matched his results re: spoke tension affecting wheel stiffness. Or rather I should say it hasn't been obviously wrong, because I am just riding the wheels, not measuring their deflection under a known load as he did. Our feel is not finely calibrated and is affected by our hopes and beliefs. I.e. the "new bike effect" making someone's average speed 1 mph faster on their regular loop. I am pretty well attuned to what my bike is doing but I am not going to claim I can feel a 7 thou difference in lateral flex.


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PostPosted: Thu Feb 14, 2013 3:45 pm 
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"1. The Rim will provide the real Lateral and Radial Stiffness (ie a flexy rim will always be flexy regardless of spoke tension)"


I'd suggest... one can significantly increase the stiffness of a flexy rim with spokes that do not flex/stretch easily. IMO the 'real' stiffness is again a function of the entire unit.

"He was testing an actual wheel. That's "real world". (Rinard.. please excuse typo earlier)

Very true.. I included referencing the online book per wheel building.

My point.. is simply this: discussing present day real world examples I can learn something tangible from. List the components.. the conditions the outcomes were derived from.. then how that outcome is related to that SET of components. IE: what works.... and what does not... and WHY.

This in-depth discussion.. and how to cheat the scale building strong wheels... I find very informative.

Anyone ever build a triplet with the NDS tension higher than the DS?


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PostPosted: Thu Feb 14, 2013 5:04 pm 
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I'm tired of building wheels....

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PostPosted: Thu Feb 14, 2013 5:54 pm 
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Location: Glermsford, Suffolk U.K
A 559 ETRTO rim on a hub with a 60mm flange and 40 spoke holes, would 4x lacing have the spokes crossing the hub flange or would I need to use 3x. If this was a 622mm rim I would bet 4x would be the best option. As the ERD of the rim in 537mm I am not sure if 4x will work as well and whether 3x is a better bet. I need to order spokes for this tandam build. Any thoughts.

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PostPosted: Thu Feb 14, 2013 8:21 pm 
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Location: Slovenia---that forest land
Eric thx for youtube link.
Digital scale are not cheap (200 kg) , maby analog will be better. But digital looks better

Now i must find safe place to place "callibration device" :D

bm0p700f maby drawing a complete wheel and lacing is the best option

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PostPosted: Thu Feb 14, 2013 8:31 pm 
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Joined: Tue Nov 11, 2003 9:47 pm
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Location: Santa Cruz, California, USA
I found the same scale on amazon for $50. I needed a scale with that sort of range anyhow for a non cycling project.

You could do it with a rig that lets you hang weights from a spoke. Then you'd be limited by the accuracy of the weights, or of the scale you used to weigh them.

The good thing about the scale is that (theoretically) you could calibrate the tensiometer in 10kgf increments or whatever increments you wanted.


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Posted: Thu Feb 14, 2013 8:31 pm 


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