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built a "aero" front wheel - 24 spokes on 36 hole rim(8 posts)

built a "aero" front wheel - 24 spokes on 36 hole rimoff roadie
Aug 27, 2002 6:27 AM
Here's some pics of my attempt at a slight aero improvement for my road bike.

Full face view, showing the pattern:


3/4 view showing the spoke spacing:


Componants:
36 hole 105 front hub
36 hole Velocity Deep V
24 Wheelsmith AE15 spokes
24 16mm brass nipples (wish I'd used 12mm alloy)

Construction:
Its laced with all the spokes heads in. Spokes on each side are laced one cross, 40 degrees apart at the hub and 20 degrees appart at the rim. This creates 12 sets of "paired spokes" and leaves 12 equally spaced empty holes in the rim which I coverd with reflective tape as shown in the photo.

Commentents:
Rides nice so far. Obviously no trouble with spoke windup, and its quite true. It probably sacrifices some lateral stiffness when pushed away from widely spaced spokes, but seems otherwise sturdy. Weight doesn't seem all that bad- with alloy nipples, I figure it would favorably compare with similar commercial designs. I figure its about the same strength as Velocities own 20 spoke "Sparticus" wheel which uses similar lacing on a custom drilled Deep V.
you're not the firstAndreas_Illesch
Aug 27, 2002 8:21 AM
http://www.radplan-delta.de

this is a website of a german wheel builder who uses series rims (nearly serial, he made some agreements with the manufacturers concerning the hole number), series hubs and spokes.
he claims that his wheels despite the low spokes number are strong and stiff due to his unique spoke lacing. i haven't rode one of his wheelsets yet, so i can't say about the quality.
perhaps you can get some advise and impressions from the pictures on the website.

here is a translator website if you need it.
http://www.systransoft.com/
Not first by a long shotoff roadie
Aug 27, 2002 10:52 AM
I didn't figure I was using a novel concept- the lacing I did combines aspects of lots of modern low spoke count wheels I've seen. Its essentially a modified crows foot pattern- just remove the radial laces. Not a new idea. I was gonna buy my spokes from Harris Cyclery (ended up with Mike Garcia at Oddsnendos)- Sheldon said he'd built exactly such a wheel many years ago using a conventional rim, but had trouble with high spots. The Deep V (and other rims used for "real" paired spoke wheels) doesn't have that problem, and mine doesn't quite follow normal crow foot lacing, but its hardly groundbreaking. In fact, I built a crow foot (adding the radials only after the slanters were tensioned) for practice before doing this wheel, just to see how hard truing it would be.

That German site is intersting. There is obviously a lot of custom rim drilling involved in making some of those patterns work right, but the translator page wasn't much help. I don't see why those wouldn't be reasonably stiff and strong, but I'm more impressed with the new American Classic wheels...
Not first by a long shotAndreas_Illesch
Aug 27, 2002 11:47 AM
what are "new american classic wheels"?
http://www.amclassic.com/index.htmloff roadie
Aug 27, 2002 12:50 PM
American Classic hubs are among the lightest. The 350 and 420 rims are amazing, and the company has a very good rep for quality wheelcrafting.

I dunno when they last updated the website, but it says the 420 wheel is new.
How did you figure the spoke lengths? (nm)Spoke Wrench
Aug 28, 2002 5:35 AM
a couple waysoff roadie
Aug 28, 2002 9:23 AM
In the picture below, I've marked the path a leftside (the side facing us) radial spoke would take in red. The path of an actual leftside spoke on the same side is marked in grea, as are all 18 holes in the rim that are drilled for leftside spokes.

As you can see, the spokes actual path is offset from radial by more than 1 hole, but less than 2. In a normally laced wheel, a 1 cross spoke is offset by 1 hole (20 degrees for 36 holes), a 2 cross spoke by 2 holes (or 40 degrees), etc. Mine is ofset by "1.5" holes (30 degrees), so its "1.5 cross".

Daimin Rinards "Spocalc" spreadsheet for Excel alows you to enter decimal cross values, so I calculated the value for "1.5" cross spokes. Sheldon Brown mentions using this method in an article on his website, bt I can't find the link right now.

I independantly confimed the value by laying out the wheel in a 3d cad program, or at least a scematic representation of it that used all the propper dimensions. This allowed me to actually "measure" the required spoke length.

The values I got by these mthods differed slightly, maybe because I hand measured the dimensions I used in the cad program, I forget. In any case, they were within 1mm of each other.

Mike Garcia at Oddsnendos.com suplied the spokes (and long nipples, "just in case") - I forget if he confirmed my math, but his shipping was fast and he was willing to exchange, so I wasn't to worried about bad calculations.

As it turned out, spocalc's values were perfect. I believe Mr. Rinard included that feature just for odd cases like this. Theres some other lacings that can be done with fractional spoke cross values. I think you can do this for any pattern by figuring out the degree seperation between the spoke head and the spoke elbow, and dividing that by the degrees of seperation between rim holes for one side of the wheel. That gives the effective decimal cross value you need to enter.
Thanks. (nm)Spoke Wrench
Aug 28, 2002 10:46 AM