wheel building: uneven tension between inbound and outbound spokes
Earl Grey
I have built a few wheels, and recently bought the Park TM-1 spoke
tension meter. On a rear wheel I am building now I noticed that all
the outbound spokes (spokes whose heads are on the inside of the hub
flange) have lower tension than the inbound spokes. This is
particularly noticeable on the drive side, where the difference is
quite consistently 10-20 kgf (kilogram force) all the way around the
rim. All the outbound spokes are around 110 kgf (+-5%) and the inbound
spokes are all around 95 kgf (+-5%). I follow Sheldon Brown's wheel
building guide and also consult Jobst Brandt's "The Bicycle Wheel".
Btw, plucking the outbound spokes produces tones not quite half a note
lower than plucking the inbound spokes.
My guess is this difference is the result of manually bending (only)
the outbound spokes an inch from the spoke elbow by pushing them
inward with the thumb to assume a straighter line per Sheldon's
instructions. Has anyone noticed such consistent spoke tension
differences between out- and inbound spokes?
I assume that the tension will even out over time as the inbound
spokes assume a straighter line, and that the wheel will stay true.
However, I am just curious whether bending the inbound spokes as well
as the outbound spokes before tensioning the wheel would create more
balanced tension right from the start, which would facilitate reaching
even tension while building a wheel.
Any thoughts?
Thanks,
Gernot Huber
Chalo
Is the wheel laced mirror image or identical? It sounds to me like an
imbalance on one flange may be offset by a matching imbalance on the
other flange, with a higher tension on one side's leading spokes
working against a higher tension on the other side's trailing
spokes.
This places a static torque across the hub shell, which many recent
hubs with their fat centers are able to carry.
Chalo
thirty-six
> Hi,
>
> I have built a few wheels, and recently bought the Park TM-1 spoke
> tension meter.
Tut tut.
> On a rear wheel I am building now I noticed that all
> the outbound spokes (spokes whose heads are on the inside of the hub
> flange) have lower tension than the inbound spokes.
Really, how have you assertained that?
>This is
> particularly noticeable on the drive side, where the difference is
> quite consistently 10-20 kgf (kilogram force) all the way around the
> rim.
Oh, with your hoogywotsit.
> All the outbound spokes are around 110 kgf (+-5%) and the inbound
> spokes are all around 95 kgf (+-5%).
Indicated only.
>I follow Sheldon Brown's wheel
> building guide and also consult Jobst Brandt's "The Bicycle Wheel".
> Btw, plucking the outbound spokes produces tones not quite half a note
> lower than plucking the inbound spokes.
Seems to confirm. But ask yourself is the rim radially true? Is
this a deep section rim?
>
> My guess is this difference is the result of manually bending (only)
> the outbound spokes an inch from the spoke elbow by pushing them
> inward with the thumb to assume a straighter line per Sheldon's
> instructions. Has anyone noticed such consistent spoke tension
> differences between out- and inbound spokes?
Er, yes, but it wasn't for that reason.
>
> I assume that the tension will even out over time as the inbound
> spokes assume a straighter line, and that the wheel will stay true.
> However, I am just curious whether bending the inbound spokes as well
> as the outbound spokes before tensioning the wheel would create more
> balanced tension right from the start, which would facilitate reaching
> even tension while building a wheel.
Not there it wont.
>
> Any thoughts?
You've tensioned up going from one spoke to its immediate neighbour
instead of skipping around the wheel using rule of seven for instance
on a 32 or 36 spoke wheel, along with overtensioning without
stabilizing the interlace. The dreaded stress relieving of spokes
will also do this because you are overtensioning two traling (or
leading spokes) at a time and it unbalances the wheel. Slacken off
all nipples for at least halve that spoke tension, level up all the
interlace crossings and form elbows there to stabilize the
crossings. Tension up the spokes going from trailing to leading spoke
and skip around the rim in approximately 2/5 (rule of seven on 32 and
36) Due to the way the wheel responded, I think you dont need that
amount of tension, assuming you have specified rim and spokes
according to the load. The trick to setting tension correctly is to
examine the length of the arc of reduction of the rim at the base of
the wheel, if this is confined within the tyre contact patch then you
have enough spoke tension.
Qui si parla Campagnolo
I would take some tension off all the spokes, take pairs of spokes and
squeeze briskly all around. Next make sure the wheel is very round,
then true again, then check roundness, then trueness again as you
approach the PROPER tension of around 100 KGF for right side rear or
front. I'm guessing it's making sure wheel is wound evenly, rotated
evenly and the spoke line is even inside pull and outside pull.
Squeezing the paired spokes will help do this. Also stress relieving.
Additionally, good for you getting a spoke tension meter(your
hoogywotsit, yikes). The way to know what the tension is, regardless
of whether the rim is 'deep' or not.
thirty-six
Pointless
>Next make sure the wheel is very round,
That is usually true before tensioning up spokes.
> then true again, then check roundness, then trueness again as you
> approach the PROPER
Based on what?
> tension of around 100 KGF
> for right side rear or
> front. I'm guessing
You sure are.
> it's making sure wheel is wound evenly,
Wound with what, twine and shellac?
> rotated
> evenly
Rotated about what?
> and the spoke line is even inside pull and outside pull.
> Squeezing the paired spokes will help do this.
Wlill help to rotate the rim concentrically around the hub which may
lead to the same result.
>Also stress relieving.
> Additionally, good for you getting a spoke tension meter(your
> hoogywotsit, yikes). The way to know what the tension is, regardless
> of whether the rim is 'deep' or not.
Which is irellevant and only leads to the errors of constructrion so
presented. There is no MAGIC tension, each rim is different to the
last and each rider is different, you are playing into the hands of
factory built machine wheel builders. They can build the one size
fits all wheel quicker than I can and they can do it repetively all
day long. They will betyter their wheels so thety are superior to
your own and you will lose the wheel business. You need to improve
your wheels to stay ahead.
datakoll
and 'the rule of seven' ?
thirty-six
> what is: mirror image or identical ?
He means symetrical lor astmetrical lacing, whether or not ta
particular spoke direction is on the same side of the flanges
>
> and 'the rule of seven' ?
When winding in the nipples, skipping to the seventh spoke as the next
(with 32 and 36 spokes) to tension means the rim does not deform with
moderate spoke tension because it is brought in evenly all around the
rim, together. This is the quickest way of tensioning up unless you
have a machine with multiple driver heads which will likely turn four
nipples or more together.
datakoll
know of an online diagram for assymetrical lacing ?
thirty-six
> know of an online diagram for assymetrical lacing ?
No. With asymmetrical lacing the trailing spokes are on the inside of
the flange on one side and on the outside of the flange on the other
side. It makes no difference if the bows are taken out of the spokes
and are locked at the interlace whether the trailing spokes are inside
or outside or whether they be the same or not.. Its just like having
the hub logo in line with the valve hole, it's cosmetic detail.
Anybody tells you different is acting on religious faith.
Qui si parla Campagnolo
I'm tapping out with this guy. Although we both speak 'english', me
and him and thers I see, are not communicating when it comes to wheels.
datakoll
it is written -
BUILDING WHEELS IS EASIER THAN COMMUNICATING WHEEL BUILDING
thirty-six
Only because you cannot provide satisfactory answers for your beliefs
and are vague in your descriptions. " I would take some tension off
all the spokes, take pairs of spokes and squeeze briskly all
around." , sure you do, why, to look busy?
"Next make sure the wheel is very round, then true again, then check
roundness, then trueness again as you approach the PROPER tension of
around 100 KGF for right side rear or front."
Trueness is roundness. What precisely is PROPER is dependant upon
components, use and loading and is NOT a set single value for all
builds.
"I'm guessing it's making sure wheel is wound evenly, rotated evenly
and the spoke line is even inside pull and outside pull. ", guessing
indeed.
I'm repeating myself so just answer my initial questions, give reasons
for your decisions. Think man, THINK.
thirty-six
> it is written -
>
> BUILDING WHEELS IS EASIER THAN COMMUNICATING WHEEL BUILDING
True. And building wheels is easier if you stabilise the interlace
before tensioning up.
JG
They come from slightly different angles due to the crossing.
Jobst Brandt
Spoke tension on symmetrical (front) wheels should be identical within
acoustic sensing (plucking spokes with the fingernail). You don't
need a tensiometer for that although it is useful for recording how
tight the wheel was built for a bicycle shop. Once done a few times,
tone is a clear indication of tension, assuming the same thickness
spokes.
There should be no differenced between inbound and outbound spokes,
although routine wheel builders like to put a few features in their
wheels, such as having parallel spokes adjacent to the valve stem,
having the view through the valve stem rim hole look straight at the
of the hub trademark, and having the "pulling spokes" on the inside of
the flanges because their tension increases slightly under pedaling
torque, therefore pulling the interleaved crossing point with their
"pushing" spoke companions inward, away from the chain.
This is mostly trivia, but it can be and is done by good builders who
have the skills well in hand. More important is that the spoke
threads are oiled with something like 90W gear lube before starting
and using a similar oil on the spoke nipple to rim interface. That
reduces spoke twist and thread stiction when making final adjustments.
This is all covered in detail in "the Bicycle Wheel":
http://www.avocet.com/wheelbook/wheelbook.html
Jobst Brandt
thirty-six
None of which addresses the OP's problem including that dreadful
book. You cant change the problem to fit your 'results' no matter how
hard you try. BTW spokes clipping derailler cages is eliminated by
removal of the spoke bows, lacing in a particular direction is a poor
bodge.
thirty-six
> Of course one set of spokes will have more tension than the other.
> They come from slightly different angles due to the crossing.
Like 0.072" is going to make any difference over 8" of spoke! The
slipping of the spokes at the interlace if the spokes arn't tensioned
up in pairs makes a bigger difference than this.
JG
At the hub, it's more like 6mm (flange+spoke width) to 72mm (flange to
cross), but you are correct, that's way below the spoke to spoke
variance.
Qui si parla Campagnolo
Yer an idiot-goodbye
thirty-six
n inside pull and outside pull. ", guessing
> > indeed.
>
> > I'm repeating myself so just answer my initial questions, give reasons
> > for your decisions. Think man, THINK.
>
> Yer an idiot-goodbye
Wrong again.
So why squeeze pairs of spokes, the juice?
Why in your eyes is 80kgf not the proper spoke tension, or 85, 90 ,
95 , 105?