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I've done quite a few wheel rebuilds to make them stronger, but haven't built up a wheel around a PowerTap (SL+) yet. This will be for a training set for a fit triathlete. Raw weight is not an issue, but he's probably putting a few watts done for hours at a time.

My inclination would be to do my "standard" rear wheel build, drive side X3 and non drive side Radial, but wonder if there are pros/cons to other lacings when power is involved.

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I really wonder if there are any difference in torque transmitted by radial vs. non-radial flange of the hub. –  heltonbiker Jun 28 '12 at 16:38
    
That hub appears to be larger in diameter than the normal hub. This means that there's less distance to achieve spoke crossing, and the spokes will approach the rim at a more oblique angle. For these reasons you may want to use a 2x lacing, and, for strength, do both sides 2x. (Hard to say until one sees the hub in the context of its rim, though.) I can't see how the power meter function could add any (significant) additional load/stress, though. –  Daniel R Hicks Jun 28 '12 at 17:14

2 Answers 2

up vote 5 down vote accepted

According to the FAQ on their website:

Note: PowerTap hubs must be laced with a minimum 2 cross pattern to avoid damage to the hub and maintain the warranty."

That suggests that making the non-drive side radial could lead to warranty issues. Radial lacing does stress the flange more than tangential lacing so many hub manufacturers do not allow it. To work on a driven wheel it also needs a certain amount of torsional flexibility in the hub which large-flange solid hubs don't have (Rohloff, PowerTap for example).

I would go with a ye olde traditional 3x lacing, and lean more towards 2x and bladed spokes than other options if the rider wants to spend more money.

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+1 for the reference to the PT FAQ. The number of crossings will also depend on the depth of the rim: you may not be able to get a 3x on a deep rim (though you shouldn't need to -- a relatively shallow training rim and a wheel cover will work fine for almost all triathlons). To get consistent readings from the PT's torque tube you should not use radial lacing on the left side. –  R. Chung Jun 29 '12 at 14:48

I have built a Sheldon Brown POWerwheel to a home-made recumbent I have (photo).

Although the idea seems a bit absurd (two leading spokes for each trailing spoke), it worked great for years without any issue, gave a very discrete visual (you only notice it is a powerwheel if you look close), and in the end it is possible that it actually MAKES a difference (at least it doesn't do any harm).

enter image description here

There are some conditions, though:

  • The wheel needs to have number of spokes multiple of three (36, 24, etc.);
  • Your client must "buy" the idea;
  • Both of you cannot be overconservative about wheelbuilding...
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Cool stuff...I think I may have to build a wheel for myself like this. I'm guessing you'd want to use a rim that doesn't have a big bias on the drilling (holes are more centered with less angle). –  Ken Hiatt Jun 28 '12 at 18:57
    
@KenHiatt Actuallly the spoke angle at the flange AND at the rim are the same of a regular crossed pattern (Don't remember if you must use the same spokelength of a 2X or 3X pattern, though) –  heltonbiker Jun 28 '12 at 20:12
    
+1 purely for the POWerwheel reference. But the interesting lacing pattern is also amusing. –  Kohi Jun 28 '12 at 23:22

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