Bladed spokes and tensiometer?

Alan-<< How would you verify the tension of a wheel built with bladed spokes such as Sapim CX-Rays?
Would the tensiometer readings still be valid?

It is for the new DT tensionometer...

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Quoted message said:

It is for the new DT tensionometer...

No, for the standard Wheelsmith one. Just not sure if the deflection measurement is accurate and
reliable if I were to use it.

alan

On mine there is no conversion table for that size of spoke. Even when the spokes are bar tight the
deflection readings are still very small (10-15). I just used the table column for 0.9x3.1 spokes
and a fudge factor to account for the spokes only being 0.9x2.3 cross section.

Nick

"Alan" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

Quoted message said:

It is for the new DT tensionometer...

No, for the standard Wheelsmith one. Just not sure if the deflection measurement is accurate and
reliable if I were to use it.

alan

Nick Payne said:

Quoted message said:

Quoted message said:

> How would you verify the tension of a wheel built with bladed spokes such as Sapim CX-Rays?
> Would the tensiometer readings still be valid?

Quoted message said:

Quoted message said:

Quoted message said:

It is for the new DT tensionometer...

Quoted message said:

Quoted message said:

No, for the standard Wheelsmith one. Just not sure if the deflection measurement is accurate and
reliable if I were to use
it.

Quoted message said:

On mine there is no conversion table for that size of spoke. Even when the spokes are bar tight
the deflection readings are still very small (10-15). I just used the table column for 0.9x3.1
spokes and a fudge factor to account for the spokes only being 0.9x2.3 cross section.

These instruments all measure across the spoke thickness so the thickness enters into the reading.
For this reason I built my own instrument that was in small production for a year or so, first under
Avocet, and then under DT. In all about 120 reached the market. Unfortunately, all such instruments
are designed by people unclear on the problem.

The bending stiffness of the spoke also enters into the measurement that is based on the theory that
the spoke is a flexible strand although it is not entirely so. For that reason a small test load
that causes little bending must be used, but this in turn requires a precise measuring instrument.
For that purpose I used a 0.0001 resolution dial gauge.

In addition, small irregularities in spokes are large enough to distort readings and for this
purpose my instrument had a "tare" zero adjustment that was set in situ. Currently the tensiometer
problem is not served as well as it could be.

Jobst Brandt [email hidden] Palo Alto CA

Quoted message said:

adjustment that was set in situ. Currently the tensiometer problem is not served as well as it
could be.

So what to do for bladed spokes?? Best guess?

alan

Alan who? said:

Quoted message said:

adjustment that was set in situ. Currently the tensiometer problem is not served as well as it
could be.

Quoted message said:

So what to do for bladed spokes?? Best guess?

I use my tensiometer that is accurate for spokes of any thickness less than 2.5mm diameter, a number
I think approaches the stiff bar of steel size.

Jobst Brandt [email hidden] Palo Alto CA

Quoted message said:

I use my tensiometer that is accurate for spokes of any thickness less than 2.5mm diameter, a
number I think approaches the stiff bar of steel size.

I may be confused but aren't all spokes pretty much less than 2.5mm, all of DT's spokes are.

Alan "confused" Wu