Looking at my Dt Swiss Spoke Tension Chart...

not necesarily less tension to operate, but they read lower on the meter. While in use they actually have teh same tension. They flex a bit more, stretch a bit more, they are lighter BLAH BLAH BLAH. There is alot to it, alot more than what I started here.

Its hard to explain, there are alot of books out there that go over spoke tension's in pretty good detail. Also check out Sheldon browns website, alot of good info there as well.

good question

Generally spokes that are butted, bladed, or titanium need more tension than straight gauge spoke to do the same job. When using a park tension meter for example to get a reading of 22 a butted supercomp spoke will need more tension than a straight gauge spoke.
here is some more info on the topic:
http://www.cyclingnews.com/tech/fix/?id=tm_1

You are confusing tension in the spoke with deflection.

Spoke 'tensionometers' do not measure tension....they measure deflection. You then use the chart to 'guess' what the tension of the spoke is so as to deflect that much. Because thinner spokes have less bending strength and also are more able to stretch in length, they deflect more at a given tension.


This stretch or yield is also what makes a DB spoked wheel more durable (and less stiff) than that same wheel build with straight gauge spokes. They (DB) tend to keep a more stable tension value as the wheel is put through dynamic stress...think of them as very stiff springs that are pre-stretched a bit....where as a single gauge spoke is more likely (due to less ability to stretch) to see vast swings in tension as the wheel is used. THis variation in tension in time can do several things....impart more fatigue to the spoke, or incertain cases, completely unload the spoke (zero tension) vastly effecting the strength of the wheel as a whole.


The max spoke tension will be determined by the rim in general, as just about any spoke will physically allow a higher tension than the rim at the spoke mount.

davep said:

...they measure deflection. You then use the chart to 'guess' what the tension of the spoke is so as to deflect that much. Because thinner spokes have less bending strength and also are more able to stretch in length, they deflect more at a given tension.

Click to expand...

so basically, the more the deflection the higher the spoke tension, so it's simply due to the properties of the straight gauge spoke

More tension the less deflection....but there will be more deflection with a less stiff item (thinner spoke).

Think of it this way in an exaggerated example..

an iron I beam under zero tension will have very little deflection even with a large force applied perpendicularly to the mid-span

Now take a thin piece of wire of the same length and apply the same force to the middle...it will deflect a LOT more no matter the static tension on the wire.