Originally Posted by
Aeneas
Thank you for the suggestions to this point and for the explanation of bicycle wheel engineering. I remembered that there is a bike coop on campus the president of which I'm friends with so I can probably use the truing stand and other equipment there, and maybe get some instruction as well. Could you suggest a reference, either hard copy or web-based for bicycle wheel construction (yes, I've read and reread sheldon's page) and dynamics? Why are there different spoke gauges and why are the mechanical properties different?
dabac, pardon my ignorance, but could you explain what you mean by "heads-out half radial?"
I haven't found any web-based wheelbuilding stuff that has as much technical detail as:
The Bicycle Wheel - Jobst Brandt
Spoke gauges are selected based upon weight, load and durability. Thicker 14ga (2.0mm) spokes are pretty standard on common department-store bikes and they're fairly reliable and bulletproof. Thinner 15ga (1.8mm) spokes are favored by racers due to the weight-savings (about 1/4-1/2 lb per wheelset), but they tend to fatigue and fail sooner. But 2-3 years is fine for a racer, even 1-year is sufficient.
Double-butted spokes is a combination and yields weight-savings WITH durability. That's because the most stressed parts of a spoke are at the ends where the bend through the hub occurs; and to a lesser extend, out by the spoke-nipple. So a 14/15/14ga (2.0/1.8/2.0) spoke has most of the weight-savings of a 15ga spoke, yet has the strength of a 14ga spoke. It's actually better than both because it has higher-stretch than 14ga for the same tension. This ensures that it can go through a wider-range of loads without losing tension completely. Losing tension causes the nipples to be loose at the bottom of the rotation and vibrations will loosen them, causing the wheel to go out of true over time. The all-tension/no-tension transition is also harsh on the material and will lead to fatigue-failure sooner than if the spoke were kept tensioned all the time.
A very good spoke to use for clydes is the DT Alpine spoke in 13/15/14ga (2.3/1.8/2.0mm). It has the thickest part at the bend for strength as well as fully filling the spoke-hole in the hub. Yet it doesn't have excess weight
and it has additional stretch from the butting. Be sure to pick these up for your new wheel.
"Heads-out half-radial" refers to lacing-up the non-drive side spokes on your rear-wheel. Radial is spokes going straight from the hub to the rim without any tangential angles or crossing. The heads-out means the spokes sit on the inside of the hub-flange. This reduces the angle of the spoke to rim and matches better the angle of the spokes on the drive-side. Matching the angles more results in more similar tensions and more even load-bearing from all the spokes.
Borrow a tension-gauge or have your tension inspected by a knowledgeable wheel-builder. You'll want to have tension towards the high-end of the range for the specific rim you're using. Something around 125-140 kgf. Most stock wheels on bikes are way undertensioned at 80-100 kgr and this leads to faster fatigue failures.