Measuring tension on short DB spokes?

The WheelSmith tensiometer I got last week seems to work OK, but the
instructions say it has to be applied away from the butted area.

Only problem is that on my rear wheels the hub is so big that there's not enough
space between the non-butted area and where the spokes cross to fit the
instrument.

I'm guessing the conversion factor just changes to something between the narrow
diameter and the butted diameter. Does anybody have a fudge factor for this
situation?
-----------------------
PeteCresswell

"(Pete Cresswell)" wrote in message
...
The WheelSmith tensiometer I got last week seems to work OK, but the
instructions say it has to be applied away from the butted area.

Only problem is that on my rear wheels the hub is so big that there's not
enough
space between the non-butted area and where the spokes cross to fit the
instrument.

I'm guessing the conversion factor just changes to something between the
narrow
diameter and the butted diameter. Does anybody have a fudge factor for
this
situation?
-----------------------
PeteCresswell

I would suggest you forget accuracy and go for repeatability by measuring
each spoke in the same way. High even tension is what you are after. While
having the foot of the gauge on the thicker part of the spoke will throw the
reading off, at least measuring all the spokes the same way should give
similar readings if their tension is the same.

Mike

RE/

That's not a good idea because it serves no purpose except to make
wheel truing and tensioning extremely tedious. Since equalizing
tension is a repetitive and individual process, it should go rapidly
with quick feedback after adjustments. That is why this is done by
the tone of plucked spokes for all but the seriously tone deaf, who
are at a great disadvantage in this business. I wouldn't wish that
hurdle on people who want to build wheels.

I'm among the seriously tone-deaf.

But actually, when I did a wheel from scratch (i.e. backed all the nipples off
until the spoke was even with the top of the nipple) then tightened each spoke
an exact number of turns, dished the wheel the same way, and then trued it; the
tensions came out within 5 kg of each other.

Seems to me like my main use of the tensiometer is to keep me from exceeding the
rim manufacturer's spec and, when trying to true a wheel, to spot grossly out-of
tension spokes.
-----------------------
PeteCresswell

Pete Cresswell writes:

That's not a good idea because it serves no purpose except to make
wheel truing and tensioning extremely tedious. Since equalizing
tension is a repetitive and individual process, it should go
rapidly with quick feedback after adjustments. That is why this is
done by the tone of plucked spokes for all but the seriously tone
deaf, who are at a great disadvantage in this business. I wouldn't
wish that hurdle on people who want to build wheels.

I'm among the seriously tone-deaf.

But actually, when I did a wheel from scratch (i.e. backed all the
nipples off until the spoke was even with the top of the nipple)
then tightened each spoke an exact number of turns, dished the wheel
the same way, and then trued it; the tensions came out within 5 kg
of each other.

Seems to me like my main use of the tensiometer is to keep me from
exceeding the rim manufacturer's spec and, when trying to true a
wheel, to spot grossly out-of tension spokes.

I hadn't seen any tension specifications given by rim manufacturers.
Which rims have such information?

Jobst Brandt

RE/
I hadn't seen any tension specifications given by rim manufacturers.
Which rims have such information?

Mavic gives a figure of, in their words, "90-110 daN" - which I take to be about
100kg.

So I just check my wheels for tensions excess of that.

Interestingly, the wheel I did myself came out with the spokes within 5 kg of
each other while the wheel I just picked up from the "professional wheelbuilder"
(who said he had a "$300 tensiometer"...but didn't name the brand) had spoke
tensions all over the place....so much variation that I'm already getting the
urge to unscrew all the nipples and start over....but the problem is that wheel
has DB spokes and my dinky little WheelSmith can't give an explicit reading
because the distance is too short between the end of the butts and the
crossover. OTOH, I could probably average the readings of the newly-built
wheel and call that "100 kg"....

I've got a PDF that came from Mavic, but don't know the URL. I'll mail you a
copy of the .PDF if you want.
-----------------------
PeteCresswell

Pete Cresswell writes:

I hadn't seen any tension specifications given by rim
manufacturers. Which rims have such information?

Mavic gives a figure of, in their words, "90-110 daN" - which I take
to be about 100kg.

So I just check my wheels for tensions excess of that.

Interestingly, the wheel I did myself came out with the spokes
within 5 kg of each other while the wheel I just picked up from the
"professional wheelbuilder" (who said he had a "$300
tensiometer"... but didn't name the brand) had spoke tensions all
over the place... so much variation that I'm already getting the
urge to unscrew all the nipples and start over... but the problem is
that wheel has DB spokes and my dinky little WheelSmith can't give
an explicit reading because the distance is too short between the
end of the butts and the crossover. OTOH, I could probably average
the readings of the newly-built wheel and call that "100 kg"...

I've got a PDF that came from Mavic, but don't know the URL. I'll
mail you a copy of the .PDF if you want.

That might be interesting. Sure, send me a copy.

Jobst Brandt