There's two ways to go in terms of saving weight with spokes:
- use lighter spokes; or
- use less spokes.
Obviously, you could do both as well - less spokes and lighter spokes.
How much weight can I save?
- spoke from which weight savings are calculated is the DT Swiss Competition double butted spoke;
- wheelset is 32 hole - 64 spokes in total
|Spoke type||Number||Weight (g)||Weight/spoke (g)||Weight savings (g)|
|DT Swiss Competition||64||382||5.97||0|
|DT Swiss Super Comp||64||318||4.97||64|
|DT Swiss Revolution (2.0/1.5)||64||283||4.42||99|
How will lighter spokes or less spokes affect the wheel?
Lighter spokes (with less cross-sectional area) will result is a "flexier" wheel. No ifs, no buts.
Lighter spokes like CX-Rays do have a longer fatigue life than thicker double butted or straight gauge spokes, so on that basis may be considered "stronger" in terms of resistance to breakage, but they do not have some magical property that affects their elongation. It's a basic principle of metallurgy that a spoke's ability to resist stretching is proportional to its cross-sectional area. A lighter (thinner) spoke will have a smaller cross-sectional area and will stretch more under the same load as a thicker spoke.
How much more is the critical issue, and whether this additional stretch is noticeable to the rider is the real point.
I have found for off-road use I can't tell the difference in "flexiness" between a 32h wheel built with DT Swiss Competion, Super Competion or Revolution spokes.
Lighter spokes or less spokes?
For non-system MTB rims, 28, 32 and 36 hole rims are common.
For 26" MTB rims, the current sweet spot seems to be the 32 hole rim. This is the most common drilling and there's good empirical and experiential evidence that 32 spokes makes for a solid, long lasting 26" wheel. On this basis, going to 36 spokes is overkill.
But, is it worth reducing the spoke count to 28? A 28h wheel will have an optimum triangulation angle when built 2-cross (cf. 32h wheel which has an optimum triangulation angle when built 3-cross). 28h 2-cross spoke will be slightly shorter than the 32h 3-cross spoke and you'll need 4 less spokes and nipples. 4 less spokes and nipples will save around 20g per wheel. So a 28h wheel built with Supercomp spokes will have about the same spoke weight as a 32h wheel built with Revolution spokes. In theory, it should also be stiffer than the 32h wheel with the thinner gauge spokes. If we look at the total cross sectional area of we get:
|Spoke type||Diameter of thinnest section (mm)||Cross-sectional area (mm2)||28h (mm2)||32h (mm2)||36h (mm2)|
|DT Swiss Competition||1.8||2.54||71.25||81.43||91.61|
|DT Swiss Super Comp||1.7||2.27||63.55||72.63||81.71|
|DT Swiss Revolution (2.0/1.5)||1.5||1.77||49.48||56.55||63.62|
What you loose with going to 28 spokes (particularly on non-eyeletted rims) is that the stress and strain is spread over only 28 points on the rim instead of 32. A well built wheel will normally fail through cracking around the spoke holes or eyelets. Reduced spoke count rims need to be stronger around the eyelets to compensate for the reduced number of spokes. In doing so, you loose the weight reduction advantages of going to 28 spokes.