PNB

Hi everyone,

A few days ago I got a new wheel set (I already annoyed you in this regard )

Since the wheels had a few drawbacks I centered them and corrected dishing offset which was excessive for my taste.
In this process I tensioned the spokes on the DS turning the nipples of 3/4 turn.

Today I got the Park TM1 and measeured the spoke tension.
On the DS I read 155kg = 1550 N which would be a little too much.
Question is whether the device is properly calibrated.
(before you ask, spokes are the right type, DT comp. 2-1,8-2, I double-checked it)
I read of many wheel builders turning nipples till hands hurt or nipples get rounded, and on all the books I have there is the advise to keep tensionng till the rim is about to collapse.
It was no great effort to turn the nipples and, I assure you, my name is not Clark Kent.
I checked another rear wheel with aero lite bladed spokes on which I corrected dishing too, more or less in the same amount and the tension is again the same - 150-155kg.
Un this case it would really be a trouble since the rims are the single eyelet R1.1, notoriously quite delicate (max allowed tension: 110kg)

I would like to have your estimated opinions.

Thanks in advance!

Soil_Sampler

make sure you are using the correct conversion column on the chart.

if so, go 110kgf

PNB

Hi

I know the ideal value would be around 1100 N.
I´m quite confused since I expected that to reach this value would imply a significant effort and before using the tensiometer I was quite sure to be far below.
I can easily turn the spoke key (either Park or DT Swiss) with two fingers and also spoke twist is very modest (I attach pieces of post-it to each spoke to check movements) and it´s hard for me to believe that I overshot the target by almost 50%.

That´s why I´d need the advise of expert builders.

Thanks again!

wmodavis

Is the TM-1 a new one you bought? If so it should still have the factory calibration. The tensiometer should be considered a precision instrument had handled with care and stored with care. If there are doubts about its calibration it can be sent to Park for testing/recalibration. Or you might ask your LBS to compare a couple of readings with theirs.

I'd be concerned about that much over tension as you risk damage to the rim. What does the manufactureer of your rim recommend for max tension. I'd not exceed that unless you just like to push the limits and you're looking for an early wheel demise so you can buy another new set.

So, two things you have to do 1) verify the TM-1 calibration, and 2) verify mfg rim max tension spec before you can be assured all is hunky dory.

DMF 

Suggestion: Take the wheel and TM-1 to your LBS and ask them to verify your results. They'll tell you if you're not reading the tool correctly, or if something else is fubar. A good shop mechanic should love this type of customer interaction. He gets to play guru to eager grasshopper.

DannoXYZ 

You can also test the calibration on your TM-1 as well to verify its accuracy. I clamp a spoke-nipple in a bench-vise. Screw in a spoke from underneath and hang a 100kg weight from the end. Use the TM-1 on this spoke and look up the proper table for the spoke's diameter. Does it come out as 100kg? I've seen well-used Park and Wheelsmith tensiometers that were off by more than 20-30%. I wouldn't use one that's more than 10% off.

I would also use a precise micrometer to verify the spoke's diameter, I've found batches to be either mislabeled or be way out of spec.

PNB

Hi all,

To compare the instrument with another at a bike shop will be the next move.
The idea to self-check the gauge hanging a known weight to a spoke is intriguing, I just have to figure out how to proceed in the practice (unfortunately I have no workshop at home), but I´ll give it a thought.

I know the max. allowed tension of the used rimes (1100 resp. 1200 N), that´s why I´m so concerned.
If the reading is correct troubles are waiting ahead of me unless I reduce the tension, which is what I´ll promptly do as soon as I´ll have the gauge checked.

Thanks again!

Al1943

Based on Park's conversion chart my rear driveside Revolution spokes (2.0-1.5-2.0) are at 157 kgf. The rims are DT RR 1.1 single eyelet. No problems after 4 years as 6700 miles. With the tires fully inflated the tension measurements are ~5% lower. However, next time I'll use Competition spokes (2.0-1.8-2.0) on the driveside rear. Revolutions stretch too much.
I think your tension is good.

Al

DannoXYZ 

Are the rims double-section/single-eyelet or single-section/single-eyelet? There's a huge difference between single versus double-layer rims, but not so much between double vs/ single eyelets. Single-layer rims like cheapo commuter Araya rims usually don't want more than 100kgf. They can take 150kgf just fine and that'll help them stay true longer. However, at the higher tensions, they're more sensitive to taco'ing in crashes. So in one sense, they're "stronger", but more "fragile" at the same time.

I wouldn't worry about it.

maddmaxx 

There is one additional "trick" to using the Park Tensionmeter. Do not release the clamp onto the spoke quickly. Release it slowly an gently to get correct tension readings. Unfortunately I do not remember which way the guage wants to err (high or low) when used improperly.

Panthers007

Yes - a gentle but firm placement and I've never had a problem measuring the tension. The Park tool is the best I've used for this.

Al1943

From the DT website the technical drawings of the RR 1.1 single eyelet and double eyelet rims appear to be the same. I would call them double walled. They offer a lot of information about these rims and they're not cheap. I bought mine in 2004, I think they were new on the market, and the double eyelet rims had not been introduced. I guess some people were having problems with the single eyelets which would explain why they came out with the double eyelet rims. Here's a link to the technical stuff: https://www.dtswiss.com/Products/Comp...s/RR-rims.aspx

PNB

Hi Everyone,

Thanks a lot for all valuable contributions!
Meanwhile I´m quite convinced that the TM-1 tells the truth.
On the rear wheel with R1.1 Single rim I reduced the tension on DS to 1100N, which was also the value as I got the wheels (I unscrewed the nipple of the same whole turn I added)

On the other wheel with Excellight rim I also reduced the tension on DS to about 1350N.

Yesterday I got a Mail from Ambrosio stating that the max. allowed tension lies between 1200 and 1400N (their words) so I should be on safe ground.

Best regards
A

Al1943

If you have a problem it will be from not having enough tension on the non-driveside rear spokes.

dwood

Danno,

Great idea for maximum accuracy. The main problem I see is gathering up a 100kg [~220#] weight and figuring out how to attach it to the dangling spoke.

What I did was bend a piece of 3/8" X 1.5" wide steel into a shallow "U" shape [the right length for a spoke with each end of the bar bent up about 1.5"]. Each of these bent-up ends was machined to hold on one end the spoke nipple, the other end the fixed end of the spoke.

I tensioned this spoke for a mid-scale reading on my 'fresh from the box' new Park tension gauge. I checked the spoke tension a month later and it still read mid-scale. I carefully stored my 'calibration standard' away for future use if I'm ever in doubt about the Park's accuracy.

DON