Which spoke type do I need for my bike?

Question

I have a Giant Trace X3 2012

It has 26" rims. Which of these spokes type do I need for my bike? Strongest or best match for the spokes I already have.

DT Swiss Champion Stainless PG Spokes
DT Swiss Champion Stainless DB Spokes

thank you

Answer 1

The difference is whether the spoke is butted or straight gauge.

A butted spoke is thinner in the middle, which allows more flexibility without damaging the wheel, which usually makes it the stronger, as well as the lighter choice. The choice is purely personal, though, and either will function as long as the lengths are correct. Note that not every spoke in a wheel set is the same length.

Answer 2

Note that there are several parameters to spokes:

• Length (obviously). The spokes need to be within about 2mm of the originals (and not so long that they stick through the rim) in order to fit reasonably well.
• Diameter of the head. The holes in hubs are not all the same size. Your heavier mountain bike hubs will have larger holes and need spokes with larger heads.
• Diameter of the nipples. These generally change in sync with the head diameter. The rim will be drilled for a certain diameter nipple, and the new nipples need to match that. (Don't try to get by with smaller heads or nipples except in an extreme emergency -- you risk fatal damage to the rim and hub.)
• Diameter of the body. This is usually unimportant for fit, but affects the weight of the wheel and it's dynamics. For a given diameter of the head all "straight gauge" spokes will generally be close to a certain diameter, but there are sometimes small variations from one brand/style to the next.
• Straight gauge or "double-butted". As Zen's post illustrates, a spoke may be "necked down" in the center portion, leaving only an inch or two at each end that is the "normal" diameter. This reduces the weight of the spoke, cuts its wind resistance, and adds to it's "stretchiness". (And there are semi-valid claims made that "stretchy" spokes last longer and give a better ride.)
• Composition. Spokes may be galvanized steel, stainless steel, or some exotic material. Your standard good-quality spokes are stainless, and that's what should generally be used. But on "department store" bikes you'll sometimes see galvanized. If you have something exotic you know it because you likely spent $10K or more on the bike.

For replacement spokes the two critical dimensions are the length and the head/nipple diameter. Ideally one should also match double-butted or not, but it's not critical. Re length, the spoke should catch at least 6 threads (6 full turns) of the nipple, and it absolutely must not poke through to where the spoke end can contact the tube (even with a rim strip in place). You generally have the ideal length when you can see 2-3 threads above the top of the nipple.

Note that, as Zen also mentions, the spokes on the back wheel will almost certainly be two different lengths (left side vs right), and the spokes on the front are likely yet again a third length. "Fancy" wheels can have even more lengths.

There are charts and "calculators" available online that give spoke length for various standard wheel configurations (wheel diameter, hub diameter, "cross" count of the spokes, etc). They're pretty good but may be off by a mm or two for certain hub/rim combos.