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PostPosted: Sun Dec 02, 2012 4:14 pm 
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Joined: Thu Jun 25, 2009 5:29 am
Posts: 167
bm0p700f wrote:

I like this forum as posting does make me think and the above about spoke length and tension has only ust revealed it self to me thanks to the CTC forum. I am glad that poster presented the maths behind it as I wouldn't have believed it otherwise. Having said that it is obvious as the crossing number effect bracing angle.


Me too! and I really appreciate your contributions.

The last rear I built was a Nemesis rim on a 32 hole Campy Chorus hub (the large axle silver version -- drool :D ) and based on the info below from http://spokeanwheel.110mb.com/lacingsr.htm#23 I laced 3x DS 2x NDS to improve the strength.

Quote:
A mixed lacing pattern I discovered that works very well for balancing rear wheel lateral strengths is the 2-cross/3-cross lacing. This pattern uses 2-cross lacing on the non drive side and 3-cross lacing on the drive side. The non drive side spokes end up being shorter than the drive side spokes, a condition that causes theoretical force vector triangles that counteracts the dish offset of the wheel. This theoretical triangle is comprised of the real force vectors of the spokes and a theoretical force vector across the hub.

The figure to the right is a simplified version of the theoretical force vector triangles created by this lacing. The RED lines represent the force vectors of the spokes, and the BLUE line represents the force vector of the theoretical third side of the triangle. The location of a 3-cross length spoke on the non drive side is indicated by the GREEN spoke head for your reference. The PURPLE line, which is perpendicular to the BLUE force vector, indicates that the rim is closer to the non drive side of this theoretical force vector triangle.

Having a theoretical force vector triangle with the opposite circumstances of the actual triangles formed by drive and non drive spoke pairs works against the imbalance caused by the dish offset. A wheel built like this still has the drive side spokes under greater tension, but the difference in the tensions is not as great as they would be if the wheel was laced conventionally. Since the spoke tensions do not vary as much, the wheel has lateral strength characteristics that are more balanced than typical. It has been my experience that these wheels do hold true much better than conventionally laced (all 3-cross) multi-speed rear wheels.

Image


From what you've said I'm now confused about doing this; as you wrote about 1x DS 3x NDS building more even tensions.

How does one think about DS/NDS tension vs bracing angle?


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PostPosted: Sun Dec 02, 2012 8:36 pm 
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Location: Glermsford, Suffolk U.K
1x DS and 3x NDs is the most exterme version. 2x DS and 3X NDS would be better for many hubs and the load on DS flange will be lower.

Doing 2x DS and 3x NDS result in a slighter higher NDS tension compared to doing 2x or 3x both both sides. Lacing 3xDS and 2x NDs does result in shorter NDs spokes than the DS but also it will end up with lower NDFs tesnions than 2x or 3x lacing both sides would give. so I don't get the article quoted either I ran the niumbers just to be sure.

For Miche hub at DT Swiss RR415 28H.
2x DS and 3x NDS spoke lengths are 285mm DS and 296mm NDS. For 107 kgf DS tension NDS tension = 107*(16.75/285)*(296/38) = 49 kgf or 480N

3x DS and 2x NDS spoke length are 294mm DS and 287mm NDS. For 107 kgf DS tension NDs tension = (107*(16.75)/294)*(287/38) = 46 kgf or 450N.

the latter lacing pattern stricks me as poorer but DS bracing angle is the same at 3.3 degrees for 2x or 3x lacing. NDs bracing angle also remains unchanged between the two versions at 7.4 degrees. So the best option is obvious unless I made some kind of dreadful mistsake.

In principle longer spoke means lower bracing angles but changing the 1x lacing give a NDs bracing angle of 7.8, 2x =7.6 3x =7.4 and 4x =7.1 degerees. the DS bracing anles are1x 3.5, 2x 3.4, 3x, 3.3 and 4x 3.1 for this Miche DT build.

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Posted: Sun Dec 02, 2012 8:36 pm 


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PostPosted: Mon Dec 03, 2012 11:36 am 
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Location: east yorkshire
hi there im a new member anyone collect spoke keys


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PostPosted: Wed Dec 05, 2012 5:08 pm 
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Posts: 76
Location: USA
Has anyone measured a MTB SL+ disc hub to see if the dimensions Saris quotes are accurate? I don't have calipers so the best I'd be able to do is use a ruler.

The sheet that came with my hub says:
NDS flange 74.0
NDS center to flange 33.9
DS flange 70.0
DS flange to center 15.9


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PostPosted: Thu Dec 06, 2012 10:16 am 
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Anybody had any experience with the BHS SL218 16:8 Rear Hub ... http://www.bikehubstore.com/SL218-p/sl218.htm


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PostPosted: Thu Dec 06, 2012 11:24 am 
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Location: LA/OC, California
I have used the SL218 rear hub to replace the stock hub on a pair of Reynolds Assault tubulars. I broke the axle on the Reynolds by accident while working on it, and turns out the dimensions of the SL218 are so similar that it was a straight swap, reusing the spokes and all.

The hub engages very nicely, and has very little freehub drag (I usually add Phil Wood tenacious oil to the freehub pawls).

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PostPosted: Thu Dec 06, 2012 11:33 am 
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Location: Slovenia---that forest land
Maby the best hubs what you get for price/performance.

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PostPosted: Thu Dec 06, 2012 1:18 pm 
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Just received a reply from BHS to say that the SL218 is compatible with either Shimano 10 or Campy 11 spd and a new freehub body for Shimano 11 should be out soon. So maybe a 16:8 hub a good way to go :-)


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PostPosted: Thu Dec 06, 2012 2:01 pm 
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ymmv, but the hub I have is definitely not 11S campy compatible.


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PostPosted: Thu Dec 06, 2012 2:09 pm 
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Location: The Netherlands
I have a chance to buy a pair of vintage Saavedra Turbo rims (280g, aluminium) that I think would be great for building myself a lightweight wheelset. The downside is the rims have 36 holes in them.

I want to make the set as light as possible, so that is why I would like to ask you what the minimal acceptable amount of spokes is according to you guys? I came across a picture (below) of a guy who used 18 spokes in his front wheel and apparently that wheel has been going strong for quite a few years now.

Is 18 spokes doable for a rear wheel? Or do I need 24? For your information, I plan to use these wheels in my time trial bike and maybe in a hill climb someday. Also, I weigh 80 kg.

Thanks in advance!

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PostPosted: Thu Dec 06, 2012 2:46 pm 
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Location: Glermsford, Suffolk U.K
Some of these older rims are a bit flexy and a 280g alloy rim is never going to stiff. They did them in 32H and 36H drillings for a reason. 18 or 24H while doable in principle will most likely for most riders lack suffient stiffness. Build with the lightest spokes you can and alloy nipples and the wheel with 36 of them will still be quite light as the rim is very light.

Actually my advise would be 36 spoke count only unless you weight 25 kg.

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PostPosted: Thu Dec 06, 2012 2:47 pm 
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I can see it working as a front wheel, but lacing that to a 24 hole hub with 8/9/10 or even 11 speed dish?


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PostPosted: Thu Dec 06, 2012 3:14 pm 
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Location: The Netherlands
I would definitely like to do 18 spokes for the front wheel. With Sapim Laser spokes this would save me some 150g over the 36 spoke wheel, which is a lot in my book.

I am not looking for a stiff wheel or one that I could use for road racing. Just a lightweight set for smooth surfaces.

Concerning the dish: I would happily go for a 3-5 speed wheel but unfortunately there are no lightweight options available for this. Even the Tune singlespeeder is silly heavy. Both the Mavic Cosmic Pro and the Campa Shamal wheels used 16 spokes, so do you really think it is not going to work?..

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PostPosted: Thu Dec 06, 2012 3:46 pm 
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Both of those used very heavy stiff rims.


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PostPosted: Thu Dec 06, 2012 7:42 pm 
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Joined: Tue Nov 11, 2003 9:47 pm
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Location: Santa Cruz, California, USA
KLabs wrote:
Anybody had any experience with the BHS SL218 16:8 Rear Hub ... http://www.bikehubstore.com/SL218-p/sl218.htm


I have one in regular 28h. It's a solid hub, similar to the SL211.


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Posted: Thu Dec 06, 2012 7:42 pm 


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