Calibrating Park Tool TM-1 spoke tension meter

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Brucey
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Re: Calibrating Park Tool TM-1 spoke tension meter

Postby Brucey » 16 May 2018, 11:37am

Dsan wrote:Hi, I'm new to this forum, and start with a question about spoke tension of the zipp 202 Firecrest clincher.

According to zipp, the sapim cx-sprint have 2.25mm width and 1.25mm thickness. If you use the park tool tension web app, for these spoke measures, 100kgf correspond to 17 in the park tool tm-1 tension meter. Am I right?


that is what it says, yes. Whether it is correct or not is another matter; it says exactly the same thing if you exchange the width and thickness measurements when you enter them.

Looking at the chart it suggests that your steel blade is comparable with a 1.5-1.6mm steel round spoke or a 1.4 x 2.6mm Ti blade; seems believable to me.

http://www.bikecoop.ca/wp-content/uploads/2014/07/TM-1-Tension-Meter-Conversion-Table-1.jpg

cheers
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Mick F
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Re: Calibrating Park Tool TM-1 spoke tension meter

Postby Mick F » 16 May 2018, 12:07pm

Just a question, a sort of "small wheeled bike" question.

How do these spoke tension meters get on with short spokes?
I could imagine that long spokes would deflect more than short ones as there's less length to stretch.
Mick F. Cornwall

Brucey
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Re: Calibrating Park Tool TM-1 spoke tension meter

Postby Brucey » 16 May 2018, 12:29pm

in theory the spoke could deflect a small amount, purely elastically, and there would be

a) little or no perturbation outside of the tool and
b) in fact the bending stiffness of the spoke becomes a smaller part of the whole reading

In practice most commercial spoke tension meters (eg the park tool one) use a high spring force and the bending stiffness of the spoke is important. By the same token the bends at the ends of the spoke tension meter must extend beyond the meter itself and the reading may be influenced by the constraint of the spoke ends etc. I'd expect this to make short spokes read a bit tighter than they really are, but I don't know by how much this is likely to happen.

However in meters that don't have a zero reading check with every tension reading there is another source of error which is how straight the spoke is to start with. The intention is that the high force negates errors that arise this way but even so such errors may still be significant.

cheers
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MikeDee
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Re: Calibrating Park Tool TM-1 spoke tension meter

Postby MikeDee » 26 May 2018, 3:56pm

I've got an issue with my Park tension meter. Put it on a spoke, squeeze and let go, get a reading. Squeeze and pull apart or jiggle a little and get a higher reading. It's like there's some binding or hysteresis in the gage. Anyone else have this problem? If so, what's the correct reading?

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SimonCelsa
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Re: Calibrating Park Tool TM-1 spoke tension meter

Postby SimonCelsa » 26 May 2018, 7:21pm

I've given up with mine now and just go by feel. I don't build too many wheels and those I do are normally fairly heavy duty so I just wind things up until just before the nipples round. I had a similar problem to you, discrepancies on measuring the same spoke. I also found the calibration a bit hit and miss, adjusting the spring tension, even by a vast amount, made very little difference to the readings. I think you really need to spend a good few more quid to get a reliable instrument, and thus I would leave this to the professional wheelsmiths. My tensionmeter now languishes in its box and I'd feel a little guilty if I tried to sell it on.

All the best, Simon

drossall
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Re: Calibrating Park Tool TM-1 spoke tension meter

Postby drossall » 26 May 2018, 9:52pm

I know some of what you mean, but I find that at the least I can get consistent tension with mine, by being consistent how I use it on each spoke. I think I'm better with it than without, though I can see why a much more pricey professional one would be needed if I built a lot more wheels than I do.

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531colin
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Re: Calibrating Park Tool TM-1 spoke tension meter

Postby 531colin » 27 May 2018, 6:29pm

MikeDee wrote:I've got an issue with my Park tension meter. Put it on a spoke, squeeze and let go, get a reading. Squeeze and pull apart or jiggle a little and get a higher reading. It's like there's some binding or hysteresis in the gage. Anyone else have this problem? If so, what's the correct reading?


Why not go the whole hog and lever it with a nailbar?
Put it on a spoke, squeeze and let go. Do it 3 times and you will get a good idea of what the "reading" is.
.....at least, you'll get a much better idea than "crank the tension up until I'm frightened the nipples will round"
They are a simple tool, and more than adequate for the simple job of building first-class bike wheels.**
.......unless you have bought one where it reads un-feasibly high tensions. We sent back a whole batch from Spa, but that must be 10 years ago or thereabouts. i've no idea about the current ones, I've been retired 5 years. (actually, 6 years next month)

**unless you get a really "good" rim, you will have some tension variation to obtain a straight, round and true wheel......this variation is, in my experience, greater than the variation you get from the gauge on one spoke.
This whole business worrying about the "exact" tension in any one spoke is pointless.....worse than pointless, its counter-productive, a bit like people who actually think its worthwhile trying to adjust spoke tension by less than one quarter turn.
Spend that amount of mental energy and time stress-relieving your wheels, and it'll be better spent.

mercalia
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Re: Calibrating Park Tool TM-1 spoke tension meter

Postby mercalia » 27 May 2018, 7:00pm

531colin wrote:
MikeDee wrote:I've got an issue with my Park tension meter. Put it on a spoke, squeeze and let go, get a reading. Squeeze and pull apart or jiggle a little and get a higher reading. It's like there's some binding or hysteresis in the gage. Anyone else have this problem? If so, what's the correct reading?


Why not go the whole hog and lever it with a nailbar?
Put it on a spoke, squeeze and let go. Do it 3 times and you will get a good idea of what the "reading" is.
.....at least, you'll get a much better idea than "crank the tension up until I'm frightened the nipples will round"
They are a simple tool, and more than adequate for the simple job of building first-class bike wheels.**
.......unless you have bought one where it reads un-feasibly high tensions. We sent back a whole batch from Spa, but that must be 10 years ago or thereabouts. i've no idea about the current ones, I've been retired 5 years. (actually, 6 years next month)

**unless you get a really "good" rim, you will have some tension variation to obtain a straight, round and true wheel......this variation is, in my experience, greater than the variation you get from the gauge on one spoke.
This whole business worrying about the "exact" tension in any one spoke is pointless.....worse than pointless, its counter-productive, a bit like people who actually think its worthwhile trying to adjust spoke tension by less than one quarter turn.
Spend that amount of mental energy and time stress-relieving your wheels, and it'll be better spent.


whats a nail bar?

Airsporter1st
Posts: 564
Joined: 8 Oct 2016, 3:14pm

Re: Calibrating Park Tool TM-1 spoke tension meter

Postby Airsporter1st » 27 May 2018, 7:07pm

mercalia wrote:
531colin wrote:
MikeDee wrote:I've got an issue with my Park tension meter. Put it on a spoke, squeeze and let go, get a reading. Squeeze and pull apart or jiggle a little and get a higher reading. It's like there's some binding or hysteresis in the gage. Anyone else have this problem? If so, what's the correct reading?


Why not go the whole hog and lever it with a nailbar?
Put it on a spoke, squeeze and let go. Do it 3 times and you will get a good idea of what the "reading" is.
.....at least, you'll get a much better idea than "crank the tension up until I'm frightened the nipples will round"
They are a simple tool, and more than adequate for the simple job of building first-class bike wheels.**
.......unless you have bought one where it reads un-feasibly high tensions. We sent back a whole batch from Spa, but that must be 10 years ago or thereabouts. i've no idea about the current ones, I've been retired 5 years. (actually, 6 years next month)

**unless you get a really "good" rim, you will have some tension variation to obtain a straight, round and true wheel......this variation is, in my experience, greater than the variation you get from the gauge on one spoke.
This whole business worrying about the "exact" tension in any one spoke is pointless.....worse than pointless, its counter-productive, a bit like people who actually think its worthwhile trying to adjust spoke tension by less than one quarter turn.
Spend that amount of mental energy and time stress-relieving your wheels, and it'll be better spent.


whats a nail bar?


One of these: https://goo.gl/images/L859gG