In this video, we will walk through the use of the WTA Wheel Tension App
for the Park Tool TM-1 Tension meter.
The WTA is an excellent system to help understand spoke tension as they relate to one another.
It's very useful in diagnosing when a wheel has a problem.
It helps you document a wheel that has been pulled correctly tight.
It also helps you teach new mechanics the concept of spoke tension.
We're going to measure the spoke tension, we're going to document it on the computer,
and then we're going to look at the charts and statistics that tell us what's going on
with the dynamics of the spoke tension.
We will need the TM-1 Tension Meter, a caliper,
a spoke wrench, a marker, a computer with internet access,
truing stand to hold the wheel, and we're ready to go.
Open a web browser and go to parktool.com/WTA for the wheel tension app.
Here, begin with wheel settings. the material drop down box has five choices.
Our material choices are represented here. Steel can either be a stainless steel or a carbon steel.
Steel is always at least somewhat magnetic,
so if in doubt, use a magnet and see if it holds gently or firmly.
Definitely a steel spoke.
An aluminum spoke will be larger - more material - it is not magnetic at all.
Spinergy PBO is a proprietary fiber material unique to Spinergy.
Titanium spoke has no magnetic properties at all - It'll be much smaller than the aluminums
and Mavic carbon fiber R2R is a unique proprietary spoke to Mavic.
For spoke materials other than steel, select the appropriate spoke type and dimensions
from the drop-down menu. The WTA will then display the corresponding conversion table.
These conversion tables can also be found on the printed chart that comes with the TM-1.
The WTA is limited to these options for non-steel spokes.
For steel spokes, the WTA can generate conversion tables for any size round or bladed spoke.
In the round spoke, we want to measure in the middle of the spoke, not at the very ends.
There can be butted spokes that are thicker at the end and thinner in the middle.
Here, we want to measure where the TM-1 would be deflecting.
Enter the diameter rounded to the closest tenth of a millimeter.
In the blade shape, we need two measurements: the thickness of the spoke and the width of the blade.
Use a caliper to measure the thin section of spoke rounded to the closest tenth of a millimeter.
Take a measurement of the width - also round it to the closest tenth of a millimeter.
We can hit update
and this produces a TM-1 conversion table that is unique to the spoke diameters that we have entered.
The TM-1 conversion table produced by the WTA gives us a range of tension readings.
Each has a corresponding spoke tension in kilograms force -
for example, a spoke with a reading of 9 has a tension pull of 66 kg.
This is unique to the 1mm by 2.2mm bladed spoke.
On a wheel, it is the rim that determines the spoke tension, not the spoke itself.
Recommendations for spoke tension can be found at the instructions page of the WTA.
Here we'll find front and rear kilogram force recommendations for several different brands.
Always consult the manufacturer for the most up-to-date information.
If you're looking for a rough idea, you would stop here.
Check the tension chart on the WTA and see approximately where you want to be
on the recommendation you're looking for.
On this wheel, we're trying not to exceed 120 kg.
I look on our chart - readings of 15 are about 117 kg
so we're trying not to see much more than 15 on the average.
So we'll grab a handful of spokes here. Fourteen,
Fifteen.
We're between 14 and 15 - we'll do 14 and a half. Do not try and be more precise than half digits.
Here, 14 and a half again. So I don't think we're beyond the recommendation that we're looking for.
Depending on if you're high or low from the target that you've selected,
you would change the spoke tension on the entire wheel.
The WTA also offers an optional wheel tension balance feature.
What this does is it helps us even the tension.
On the right side of the wheel, we're going to check and document and measure all the right side spokes
and then adjust them so they are relatively close to the same tension.
The left side spokes - we'll do the same.
This gives us a more complete picture of spoke tension,
it lets us document the work that we've done, and it's also useful in diagnosing wheel issues and problems.
To use the wheel tension balance feature, scroll down to wheel tension balancing.
Here, select the number of left side spokes and then the number of right side spokes.
In our example, we have a 20 spoke wheel - 10 per side.
We get, then, 10 entry fields on the left and 10 entry fields on the right.
For easy reference, write on the rim braking surface the numbered spoke.
This can be wiped off later with almost any kind of solvent.
So here from the valve as a constant reference,
we mark one, two, three, four all the way around - only right side spokes.
On the other side, we begin at the valve again, but now we're going to the left - one, two, three, four
this is done so that one and one on the left and right side stay together
- three and three, four and four - all the way around the rim.
From here, begin at the first spoke.
We take a reading and we can enter it in the entry field at the WTA.
Use the Tab key to move to the next field.
Using the Enter key will refresh the page each time and slow your work.
At the end, then, hit enter. The WTA will convert all your readings to a kilogram force
and produce a radar chart of the relative tensions.
Next, proceed to the right side, and again use the Tab key and hit Enter or update
and we get the left and right side tensions - kilogram force for each one
and we get a radar chart that's representative of the tension of the wheel.
The dots or data points that are closer to the center are lower in tension
it's tighter and tighter further away from the center.
As the mouse hovers around, it will give you the spoke number and the tension of that spoke.
It is normal to see these as not a perfect circle - some anomalies are possible
it does not mean it's an unusable wheel.
The wheel tension balancing page also contains a variance.
This is a plus or minus percentage amount that will help the spreadsheet call out spokes
that are outside the limit of the average.
On this wheel, we have check marks in every box -
they are all within plus or minus 20, which will produce really good wheels.
If we pick 10 percent, we can see here spokes that are outside - we have spoke three, five, and seven.
Here, we do have a couple as well - spoke five and spoke eight.
So, understand it may take more time - and possibly an upcharge if you're a retailer -
to produce tighter and tighter tolerances.
The WTA also gives basic stats for the wheel.
Left side and right side will have numbers for average tension, standard deviation,
the limits that you have selected in your variance, and also the TM-1 readings that are equal to the limits in the variance.
Check the average spoke tension against your desired kgf target
and adjust the overall wheel tension accordingly.
For more on adjusting overall tension visit wheel and rim service in the repair help section of parktool.com.
It's common to see the right side on a rear wheel be tighter than the left side.
On a disc front wheel, however, the left side tension will be higher due to the spacing from the rotor disc.
This 20-hole rear wheel turned out pretty nice. Let's have a look at a different wheel.
This wheel is a 32-hole front thru axle mountain bike wheel.
We have decent tension all the way across the left side.
We have pretty good tension across the right side.
We can see our diagram doesn't look perfect,
yet we're still within our plus or minus 20 percent.
If we change here to plus or minus 15 percent,
you can see we're actually starting to come out a little bit on the right side.
If we continue to plus or minus 10 percent, more spokes are showing to be out of that tolerance.
Let's use plus or minus 10 percent, which brings out the left side number 8 and number 9 as problem spokes.
8 being on the looser side, 9 on the tight side.
Tension balance is a process of sharing the load equally amongst the spokes.
The right side spokes will be set to be even tension to other right side spokes
The left side spokes will be set to be fairly even tension between left side spokes.
Remember - when we true a wheel, we tend to tighten tighten tighten to correct problems.
It's a habit, sometimes, to always go to one spoke to fix a problem
when we could be going to several different options.
That tends to create imbalances in tension - even if the wheel is spinning nice and true.
This wheel is spinning very nicely - but we saw on number eight and nine on the left side we have an issue.
Number eight being relatively low, number nine being relatively tight.
This spoke is eight and spoke is nine.
They both share a common zone of influence in the middle.
We're going to set our caliper to that middle spoke.
Eight is here and nine is here. We get our caliper very very close
a very narrow gap, even pulling the other caliper out of the way.
Here, we're gonna tighten the loose spoke - possibly a quarter turn.
This gap has closed up. We're now going to loosen until we get the same appearance of that same gap.
The reason is this will help keep the true in this area.
Lastly, we double check our numbers.
24 here
24.
So we've come to much closer tension on these two spokes.
We enter our new data and see where it puts us.
We enter our corrections - readings of 24 for both
we hit enter and these two are no longer a problem.
We would proceed to spokes 9 and 10 on the right side and make our corrections there.
Below the wheel stats is the print wheel set data.
This is an option for you to enter a customer's name, should they have one,
the rim if we know the rim, the type of spoke if we know it,
the hub if we know it, we could enter any notes that we would like, then we would hit save.
What happens is the WTA creates a new and unique URL.
This is something that can be emailed to yourself, you can email it to a customer,
but please note the Park Tool Company cannot get any lost URLs.
It's the responsibility of the user to track their data.
Another option is save as duplicate.
What this does is maintains all the same settings and all the same text.
If you're repeating the same type of wheel again and again,
you can simply come down and enter new readings.
A third option is the print option, and here of course you can save as a PDF
and this can be emailed without changes possible.
If you do email the URL to someone, do realize they are able to put in different numbers as they choose.
The WTA is also useful when diagnosing and documenting wheel problems.
Here, we have a 32 hole rear wheel. It shows pretty decent tension,
except we can see spoke 16 on the right side is quite low and spoke 1 on the left side is also quite low.
Here is our spoke number 1 on the left side. This is spoke 16 but from the right side.
Here, we can move the rim back and forth and we can see the problem.
This is called a flat spot.
If these two spokes were overly tight, they would pull the rim toward the hub and create this problem -
but we've seen and documented that these two spokes are actually quite loose relative to the rest of the wheel.
What's occurred is an impact has happened here that has bent the metal.
We really can't loosen these spokes anymore to return the rim to its shape. The metal has been bent.
There's nothing really going to get it back to where it used to be.
The WTA is showing the problem that we've seen on the wheel.
This can be used to help explain to our customer or to our friend why they really need to look at a new rim.
Here is a different wheel.
This is a 32 hole wheel that has had a lateral impact or sideways impact
and what we notice here is that we have a severe crossing of fthe right and left side tension lines.
It looks fairly normal until you come around to spokes 14 and 13 here.
So what's happened is through a sideways or lateral impact, the rim has been bent.
The previous user has attempted to tighten the left side and loosen the right side to get it to straighten up,
but there is no way this wheel is going to maintain much of a true.
Here, an indication again - the rim material is bent.
It'd be very difficult to keep this thing true for very long.
By taking the time to measure and document
and record on the Wheel Tension App, you can produce better wheels.
You'll have a better understanding of the dynamics of spoke tension
and be able to diagnose when the wheel just isn't working.
So, find the WTA at parktool.com/WTA
We would like to thank Chip Howat of Howat Associates
for his assistance in the creation of the TM-1 tables and spreadsheets. Thank you.