Wheel tech question

[LegendRider]

I picked up a copy of the UK publication Cyclist to read at the beach. In an article about wire spoked wheels the following statement caught my attention:

Actually a spoke will elongate by the same amount when loaded, regardless of pre-tension applied, meaning that increasing spoke tension doesn't make the wheel stiffer.

Is this true?

[ergott]

Correct. Same physics as a spring.

A significant drop in stiffness only occurs when a spoke loses all tension and no longer supports the structure (wheel).

[LegendRider]

Correct. Same physics as a spring.

A significant drop in stiffness only occurs when a spoke loses all tension and no longer supports the structure (wheel).

Does that apply to vertical stiffness, lateral stiffness or both?

[ergott]

For all intents and purposes, a spoke is loaded through it length. All its contribution to wheel strength, lateral stiffness, and vertical stiffness is along this plane.

[ergott]

Here's a good read.

http://www.slowtwitch.com/Tech/Debunking_Wheel_Stiffness_3449.html

[Mark McM]

The Slow Twitch article is very good. Another bit of good reading is Damon Rinard's wheel stiffness test (http://sheldonbrown.com/rinard/wheel/index.htm), in which he did actual measurements of wheel stiffness, including a test to see spoke tension had an affect on wheel stiffness. As noted above, as long as the spokes don't become slackened (lose all pre-tension), the static spoke tension has virtually no affect on wheel stiffness, which can be seen in Rinard's data (see "Question 1" in the link above).