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PostPosted: Wed Jul 01, 2015 7:42 pm 
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Joined: Sat May 15, 2010 2:01 pm
Posts: 70
A wheel builder once told me that it should be no problem to build my Tune mag170 rear hub up to about 130Kgf on the drive side even though Tune rate it to ~100 (1000Nm).
I built that wheel to about 105-110 DS as I've laced the wheel 2:1 so the NDS is sufficiently high that I'm not worried about fatiguing and breaking spokes due to low tension. The wheel has been bullet proof since the day i built it.


My concern is this....

Ive made my mind up to buy an Extralite CyberRear hub for my next wheel set. Extralite say to lace it with a minimum of 2x both sides. It is rated to 100Kgf +/- 10kgf.
Being so insanely light (134g) Im hesitant to build it any other way than that which Extralite specifies. Plus its not available in 32holes like my Tune hub so 24 spoke 2:1 lacing is not possible anyway. So 2x2x 24 spokes it shall be.

1)In the real world is it common practice to build with slightly higher spoke tensions than what hub manufacturers recommend?
2)Have any of you built Extralite hubs over the recommended spoke tensions and lived to tell about it?
3)Will lighter spokes on the NDS result in slightly higher NDS tension?...I'm thinking CNspoke Mac 360 aero on NDS and front and Sapim Cx-Rays on DS.

As far as i can figure 100KGF drive side will result in about 48-50KGF NDS which "sounds" too low to be of any use to anyone.....is it?

Im guessing some people will ask about my weight and riding style. I'm 78kg and spend lots of time in the mountains climbing/training, not much in the way of sprinting...but occasionally. I will use these wheels for some races but my 60mm Tune tubs are my usual race and daily rider wheels. I have alloy clinchers for really bad weather....oh and the rims will be 38mm deep, 28mm wide Chinese open mould tubulars at about 350g/piece from the same supplier as my 60mm rims which I've been really happy with.

Thanking you all in advance


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PostPosted: Wed Jul 01, 2015 8:09 pm 
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Joined: Tue Nov 11, 2003 9:47 pm
Posts: 1985
Location: Santa Cruz, California, USA
Spoke thickness does not change the tension. The tension is what you set it to on the DS, and on the NDS what is needed to balance the DS tension. What spoke thickness does change is how much the spoke stretches at a given tension. If the spoke has stretched more, then the wheel has to flex more in order to completely detension the spoke.

50kgf is pretty low, even for thin spokes like Lasers. I prefer at least 55kgf, preferably 60. The low limit on the Extralite hub would concern me. But I have a history of breaking rear wheels, primarily NDS spokes.


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Posted: Wed Jul 01, 2015 8:09 pm 


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PostPosted: Wed Jul 01, 2015 10:04 pm 
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Joined: Sun Feb 06, 2005 4:22 pm
Posts: 3592
Location: Tucson, Az.
The builder who told you 130kgf on the Tune hub would be ok is wrong in my opinion. I would generally aim to keep a 170 rear at 110 with a max of 120.

As for the Extralite, 110 on drive should be fine for you as you're not particularly heavy. However if you want to keep the weight the same but with a higher tension and since you aren't doing a 2:1, you can move to the SP version of the Extralite which is rated for an additional 20kgf.

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PostPosted: Wed Jul 01, 2015 10:58 pm 
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Joined: Sat May 15, 2010 2:01 pm
Posts: 70
straight pull you say...hi do like the look of straight pull hubs. I hadn't even looked at it for some reason. Thanks for the tip madcow!!


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PostPosted: Wed Jul 01, 2015 11:07 pm 
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Joined: Sat May 15, 2010 2:01 pm
Posts: 70
hmm i cant find it on the Extralite website. found the owners manual PDF but nothing about hub dimensions to calculate spoke lengths or bracing angles.

Do you think there would be much of a performance difference between the SL and SP versions with regards to wheel stiffness or strength?


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