Extralite CyberRear Hub spoke tensions?

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mr4fox
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by mr4fox

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

eric
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by eric

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.

by Weenie


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madcow
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by madcow

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.

mr4fox
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by mr4fox

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!!

mr4fox
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by mr4fox

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?

TheDarkInstall
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by TheDarkInstall

Resurecting this...

Extralite have the CyberRear SP at a 130kg limit. Source; the manual I got in the box with mine.

mr4fox
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by mr4fox

yeah that's what Madcow suggested above. I ended up using the SL (j-bend) version and built them up to 110kgf DS,m. I think from memory this resulted in something like 60-65 NDS. Ive only done about 2000km on them but so far i havent taken it easy on the wheels yet they've been faultless. Still early days but i'm really impressed with these hubs and looking forward to racing on them next year!

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HermesSport
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by HermesSport

TheDarkInstall wrote:Resurecting this...

Extralite have the CyberRear SP at a 130kg limit. Source; the manual I got in the box with mine.


I feel this makes them a much more viable option than previously; in light weight, low-spoke count builds, spoke tension is the best friend you can possibly have if you want to have the wheels stick together. Bravo Extralite!
Hermes Sport, San Diego CA
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sugarkane
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by sugarkane

They are pretty nice Hermes I gun for between 115-122kgs of the cyberhub sp hubs which is plenty and gives you around 50kgf on the NDS

mr4fox
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by mr4fox

mr4fox wrote:yeah that's what Madcow suggested above. I ended up using the SL (j-bend) version and built them up to 110kgf DS,m. I think from memory this resulted in something like 60-65 NDS. Ive only done about 2000km on them but so far i havent taken it easy on the wheels yet they've been faultless. Still early days but i'm really impressed with these hubs and looking forward to racing on them next year!




I think i lied in my previous post. I just check my spoke tensions with my Park Tools TM-1. I have DT Aerolites on the drive side and lighter Sapim Super Spokes Non Drive side (j-bend hubs, not straight pull). With this combo i get (very consistent ;) readings of just under 13 (over 12.5) DS and 4.5 NDS. The Super spokes have a bladed section og 2.0x0.9mm and the Park Tools conversion chart doesn't have a conversion for such a spoke. The closest the chart offers is for a 2.0x0.8 spoke and a reading of 4.5=59.5kgf for that spoke, so i guess my reading of 4.5 on the slightly larger Super Spoke would equate to a tension of just over 50-53kgf or so. my DS tension atm equates to about 105kgf. So the ratio is around 47% which is pretty close to the calculated tension ratio for these hubs based of the geometry on paper no?

I think i only went for the SP version because of cost (spokes and hubs cost more) and because i wanted to experiment with the lighter spokes front and NDS on the rear. Im perfectly happy with these wheels and really cant fault them (1098g, they feel great and haven't exploded yet!) but i think id get the straight pulls next time just to get higher tensions for piece of mind and because they look cool. I do sometimes wonder if the wheels would feel even better/stiffer if id used Aerolites/Cx Rays on the front. But its no biggie for me the way they are now.

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TheDarkInstall
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by TheDarkInstall

The rear wheel I built around a CyberRear SP is still utterly straight as an arrow, and the tensions have not moved a single bit, despite riding it very hard daily since I built it.

I feel the design of the flanges and hub geometry definitely play a part in how well the wheel is holding (as well as my 1337 building skills, of course...) I have never had a wheel hold its tension so well. Really excellent.

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