Dan Burkhart 

My issue with the Park TM-1 is that they are not individually calibrated. They all come with the same calibration sheet which, in the case of my tool is not wildly off, but not reliability accurate. I have the benefit of a calibration jig for testing the accuracy which makes the tool somewhat useful as it does give repeatable readings but I rely more on my Wheelsmith and Wheelfanatyk meters.
Even with those, I regularly check them in the calibrator on whatever spokes I am building with.

FBinNY 

Don't credit your tool with the results of your own skill and diligence.

sweeks

I take your point. But let me play "Devil's Advocate" for a moment. There are many posters here who make claims for good results in wheelbuilding using the "tone" method. However mis-calibrated my TM-1 may be, the spokes in the wheels I've built all have a nice, high musical tone when tapped. So for this distinctly amateur wheelbuilder, the tool gets me into the right range of tension.
That said, I *am* a more "quantitative" sort of guy, and I plan to construct a calibration jig some day... I drool a bit when I see the ones posted here!

sweeks

Heh... thanks! I consider myself to have a fair amount of skill and diligence, but I feel comfortable sharing the credit with my tools.
In my work world (endodontics), all the skill and diligence in the world means considerably less without the right equipment.

FBinNY 

Yes, but all that sophisticated equipment is totally worthless without your skill and diligence.

Lombard

I found the pieces on this meter are flimsy and loosen easily. I suppose it's OK to use for relative tensions, but even there, readings can vary wildly based on how slow or fast you release the handle. I find the Wheel Fanatyk tensiometer to be much more stable and reliable.

LV2TNDM

There's no way to know what spoke tension a tension meter is measuring in actual units unless it's brand new and/or you have it calibrated. Well, why not just do this at home?

I found this issue quickly with my IceToolz tension meter. The supplied charts only applied to two common spokes. And over the years, how could I know if the values were accurate anymore? (Without sending it to the mfgr. for calibration, which is a non-starter with this brand anyway.) I then happened upon a YouTube fabricator who made his own spoke tension calibrating tool. Quite simple, inexpensive and elegant. With one, there's no need for charts, no worries that your gauge is "out of calibration" and no issues whatsoever of encountering new/different/unique spokes out there.

I can't find the original YT video I found, but Dan Burkhardt made one here:

With this jig, you'll always know what tensions your tension meter is measuring. Drop it on the floor? No problem, just toss it in the jig and check it.

I'm so glad I took the time to make one for my shop.

Dan Burkhart 

I agree that calibration charts should not be blindly trusted. My first tensiometer was a Wheelsmith. I used it for many years and then suddenly I was building large numbers of wheels with CXRay spokes.
The calibration chart showed bladed spokes but not the actual cross section of the spokes I was using so I was inspired to build the calibration jig shown in my video that you posted.
I posted that video almost ten years ago and I am unaware of any that predate it.
Another consideration is how the factory calibrates the instrument before shipping.
Wheelsmith, wheelfanatyk and some of the other better tools will calibrate to a host of individual spoke cross sections and create a unique calibration chart for that tool.
The Park tool, and I suspect, its clones, all come with the same chart and the tool is calibrated to the chart by means of a spring adjustment. So they calibrate it to let’s say a 2 mm steel spoke and then readings on any other type or size of spoke is theoretical.
One of my back burner projects which I may get around to this winter is to test a couple of Park meters by taking a range of readings with as many of the spoke types listed on their chart to see how reliable those numbers are.

pdlamb

I experienced a bit of cognitive dissonance reading this thread, because I'm usually one of those arguing for the Right Tool, Properly Maintained and Calibrated, used by Skilled Technicians with Proper Training. But in this instance, I come down on the side of the Park tensiometer users. It's good enough for the purpose -- or at least my purpose.

I haven't found my Park TM-1 to be flimsy, and I don't believe I've needed to tighten any parts in the 12-15 years I've had it. (Picked it up on sale at Performance for something like $35, if anyone cares to try to date that acquisition!) I've never needed to have it recalibrated, and the only time I contacted Park about it was when I lost my spoke gauge. They sent me a new one, and a new copy of the printed calibration chart which added some bladed spokes, for free.

What's the accuracy? I guess around +/-10% worst case, but I don't really know. Repeatability is better than 5% (1 in 20 gauge markings for ~100kgf) IME. How good is individual calibration on the fancy tensiometers? Cost differential for the Park vs. Wheelsmith is what, about 4X?

Is that good enough? For my purposes it surely is. I've been able to correct some wildly divergent spoke tensions on old wheels and still maintain true. I've been able to build (and rebuild) wheels that have gone many miles with minimal retensioning required. I've retensioned several new wheels that weren't adequately tensioned after low tension let to a spoke breaking, and they've lasted as well as any other I've worked or reworked. I believe, in the last half dozen years, or about 30,000 miles, the only spokes I've needed to replace were the result of a bent derailer hanger that led to shifting the derailer into that wheel.

What if I'm wrong about suitability for purpose? It's not like this is going to cause a multimillion dollar airplane to crash. Instead, I'll hear a "twang" and notice a wheel thumps with every revolution. It'll take me 5 minutes at the side of the road to adjust the adjacent spokes so I can finish my ride, and then I'll have to replace the spoke when I get home.

What might change my mind? Perhaps if I was working at a high end bike shop that checked every wheel on every bike, with all the variations in spoke materials, shapes, and sizes, I'd want a different tensiometer. (OTOH, I'm guessing, based on the posted shop rates I've seen, even those high end shops can't afford mechanics' time to check all the wheels that come through the shop.)

LV2TNDM

Yes, I realize your video was the one I saw. For some reason, I thought it was someone else. THANK YOU again for posting that! Much appreciated.

It has made wheel building & repair so easy. Working on a Ksyrium wheel with spoke crash damage several years ago is what prompted me to purchase the scale and build the jig. Thereafter I realized that it would be needed for the X-ray spokes and many others. Again, no need to worry about spoke gauges, shapes, or even materials changing in the future - as long as I can get it into my jig, I'm golden! Heck, even the recently-released "carbon string" spokes can be checked and my tension meter calibrated for them. But not like I expect to see them any time soon!

Thanks again!

LV2TNDM

I agree with the statement that knowing actual tension values is not that important for many home users. Using the gauge to achieve EVEN tensions is probably the most common and valuable aspect of a tensiometer.

However, for those of us building and servicing high end wheels, knowing accurate tension values is paramount. For example, Chris King specifies a maximum spoke tension of 120kgf on their hubs. Going above this can "stretch" the hub flange and shell enough to actually affect bearing interference fit within the hub. This would be bad. Anyone having me service King hubs/wheels wants to know I'm doing it right. As do I! I'll add that increasing dish over the years has made achieving appropriate NDS spoke tensions more challenging. To get them high enough, you have to take the DS spokes to their limit. An accurate, calibrated tension gauge tells you when you're at or near the limit.

And with carbon rims, knowing tension values just becomes even that much more important. Last time I looked at an Enve rim at the LBS it had a $950 price tag on it. I'm not gonna be the goon that gets it wrong working on thousand dollar rims!!!