Spoke Tension Meter Calibration

[foo_fighter]

I suspected my Park TM-1 was reading high so I built one of these for about $25 in parts.

Pretty much the same design as these in the videos, but with a wooden frame.
https://www.youtube.com/watch?v=xgsz7l1GWoI
https://www.youtube.com/watch?v=N_q_nxQl97s

The TM-1 was indeed reading high by about 3 ticks. I guess better high than low. I suspect that storing the meter with the spring under tension has relaxed it a bit.

https://lh3.googleusercontent.com/3YMv86_rsaQfYkTDLF5SiwoVXfzyy7nuIf5AIAtB0jJmdiBVtt N-gOtoKZzwVZOFvhc_iPY3ocHuwlqnsJAxAd8co38E0F1Apd8OVW Km9UeHs1eqZ5YReH5XHgboBE3RTQGlaf0RRVI98w9E_gmAn33a ert1VHCLhxk6UflBKtA9LTR66v-gmC9v_iIco7_xMN2DF5Ur4tm4vqeF916Tl571DpcXS3EwYRcMs 0rytjMLE4MWX5Lz5cxHc_Dg9eht1Ybyfe8b0vBE5_ckQNwP0QJ HidKfnXAE1jqA9x9pIvRVxGhAH2ksUZMvh6tpK3TejxYo18LDn AQx-01kdK4fklVRtjJ4PJx-gFQdVFR4xinmrdZRX--34uM8ZlcGLDRuzvbpdFQ3r9ndw3y4s3K30k2nf_bCMMUG_ntOx IiQvtMgYj0slSGX4ucWBOfISJUACqgfGo8n3vRsRu2zi5pZjNN IjSGJQ6FguDgW6Oo5fYTs1dPnNHrXItp1U28exWc9jWSqsM_pG-Ak3dW488NpzrzAK6o0FF62qvmQUjgmxwK-0MXBsTo2bEMMEqGWVFNyX9QlzRB5Ure6g4X1X55kpOXoiXQyrB pkDTmHbeo-AMT1FHiG7Ye-at0Sw1z-64Dc4nQt5-GGytkryhTPGqmNa6nUFbe39dZdFw=w1136-h1514-no

[weisan]

Very cool!

I am intrigued and was thinking of building one for myself until I saw the first video where the gentleman said it seems like his wheelsmith tensiometer had retained its calibration after 9 years of extensive use. I have the exact same tensiometer so I guess I should be ok and would just save myself the trouble. :D

Thanks for sharing foo pal.

[ikecycke]

That's a pretty good setup! From what I've read, the TM-1's also tend to not be super-consistent across ranges of tension or different gauges of spokes. I seem to do all my builds with either Lasers or CX-rays, so I've thought about having separate gauges calibrated for each spoke...or just biting the bullet and buying a better gauge. Just hasn't been necessary since I only build about a dozen sets a year.

[BLD 25]

nice setup! Also, just of note, I sent mine back to Park, and their recalibration service is like $5. Not bad and pretty easy.

[Spaghetti Legs]

I’ve often wondered, for the Wheelsmith, like I have, how important calibration is, as long as you’re just gunning for the same reading between spokes.

[ergott]

When I went calibrate a Park I found the chart inaccurate. The spring rate must have been different so I made a new chart for the user. We just set the spoke at 10kg intervals and took new readings.

[Hindmost]

So a spoke tension meter can be calibrated with one gauge of spoke and be accurate for use with other gauges of spokes?

[weisan]

So a spoke tension meter can be calibrated with one gauge of spoke and be accurate for use with other gauges of spokes?

That's the baseline, and then you use the chart for the different gauges.

http://www.kstoerz.com/spoketension/images/wheelsmith_13263_source.jpg

[ergott]

So a spoke tension meter can be calibrated with one gauge of spoke and be accurate for use with other gauges of spokes?

I charted 2 or 3 different spokes he commonly uses.

[Gsinill]

Great idea, was planning to weld something out of scrap but that is much easier.
Only concern I'd have is the bent plate of the U-bolt, doesn't it give in further when you engage the tension meter, impacting the read?

[cachagua]

I’ve often wondered how important calibration is, as long as you’re just gunning for the same reading between spokes...


Yes, you're right to wonder. Spoke tension of exactly X.xx kilograms of force is far less important, as a determinant of how a wheel will behave and how long it'll last, than consistent tension throughout the entire wheel (or one side if it's dished).

But insofar as they're a bike gadget, and we like to play with our gadgets, calibrating them is part of the ritual, I guess.

[foo_fighter]

The tension meter itself doesn't add too much more tension, but the first time I brought the device up to tension, I had to wait for it to settle and tighten the bolt a bit. It's been pretty stable since.


Only concern I'd have is the bent plate of the U-bolt, doesn't it give in further when you engage the tension meter, impacting the read?

[Tall]

Cool project. Did you try and calibrate the scale at all? I'd be hesitant to trust the accuracy of a cheap-ish scale (sounds like that's what the guy who made the videos bought).

I recently saw someone post a calibration set-up where he used weightlifting equipment to create sufficient tension.

[foo_fighter]

The electronics are usually calibrated once at the factory and usually don't change much over time since it's electronic but I supposed you could weigh yourself from it to see if it matches a scale or weigh a known volume of water....next up a calibration device for the calibration device!

Cool project. Did you try and calibrate the scale at all? I'd be hesitant to trust the accuracy of a cheap-ish scale (sounds like that's what the guy who made the videos bought).

I recently saw someone post a calibration set-up where he used weightlifting equipment to create sufficient tension.