well biked

I'll take educated guesses over wild guesses anyday.

mrrabbit 

Hippy Dippy Weatherman:

https://www.youtube.com/watch?v=D1uaw3WIOlc


=8-)

well biked

I gotta give it to Al....his last forecast was spot on.

Soil_Sampler

https://www.kstoerz.com/spoketension/

Bill Kapaun

What's the effect of temperature on spoke tension AND on tensiometers themselves?
Temperature affects the elasticity of springs.
Sometimes, it can have an even greater effect on electronics.

neurocop

The only electronic components on tensiometers would be the readout LCD. I don't think any of these use peizoelectric or other electronic pressure transducers. The main effect of temperature will therefore be on the mechanical components.

neurocop

There are ways to directly measure the tension in materials (including spokes) without having to measure something else (like deflection under force) and converting that measurement into tension using a table based on material and dimensions. Such machines employ transducers that directly respond to absolute tension values. None of the available tensiometers does that. The main problem is that to directly measure tension with such a transducer you'd have to hold the spoke end-on (where it is attached to the hub or to the rim) to measure the "pull." There's no practical way to do this while building a wheel, so tensiometers deflect the spoke between the rim and the hub, and you're stuck with using conversion tables to get a tension measurement. It works quite well.

The Park tensiometer is an excellent (brilliantly designed IMHO) device and does all that any mechanic really needs.

As to "re-calibrating," all that one needs is a standard wheel with known spoke tension. The Park has a screw that adjusts the spring tension to get the read out to match the standard wheel's spoke tension. And if the spring should become FUBAR, you can get a replacement from Park. If any of that ever becomes necessary...

BTW, it is important when you use the Park or any other tensiometer to place it consistently at the correct position when taking measurments, in order to get repeatable readings.

3alarmer 

https://aebike.com/itemdetails.cfm?catalogId=39&id=706

46 bucks including flat rate shipping. About the cheapest
I've seen it, without ordering at wholesale prices.

Bill Kapaun

So how does the LCD "know" what to display without electronics? Guess? Even the display has a certain % error +/ 1 digit.
I used to build optical oceanographic instruments. Temperature compensation was EXTREMELY important.
(https://venus.uvic.ca/discover-venus/...ansmissometer/
(Interesting they still sell an instrument that hasn't been made in over 10 years?)

Aluminum rim-steel spokes. You expect they expand the same amount in the heat?

I only bring this up because some people are concerned about the 3rd decimal place accuracy and ignore some obvious things.

markjenn

Love my TM-1. Simple, straightforward, accurate enough, not too expensive. Can't imagine tuning a wheel without it.

- Mark

3alarmer 

But this thing generates revenues from page load stats (advertising),
and there are few things that generate more page loads than ignoring
the obvious things.

One could argue that ignoring the obvious is the lifeblood of BF.

Soil_Sampler

just a little late...

FBinNY 

Anyone else looking for tension meters, I have a bunch of brand new Wheelsmith units and will sell them for $40.00 including postage within the USA.

3alarmer 

If it were not for late, I'd never get anywhere.

neurocop

I believe that the LCD readouts on tensiometers work just like the LCD readouts on digital dial guages, i.e., they respond to the mechanical displacement of a plunger. Thus they measure displacement (e.g. in millimeters). As you know, there are electronic transducers that can measure force (tension, pressure, etc.), but these aren't found in spoke tensiometers.

The obvious answer to your question (do alloy rims and steel spokes "expand" the same with heat?) is of course not.

alanf

Don't drop it!

reddog3

Mr. Rabbitt- If it sounded like I was being "alarmist" maybe I'm not the best communicator. LOL

I am questioning the need for "re-calibration" of an instrument as simple as the TM-1. All tensiometers depend on a spring to produce some deflection on a given spoke. I'm only discussing the Park Tool TM-1 here. The only part that might change in value/tension is the spring. I didn't measure the spring at rest versus fully torqued, but by using my fingers there didn't seem to be much difference. My loose guess is that the spring is about 10 psi in either position.

If that is the case, and I'd assume it is, because the value needs to be the same regardless of rotation/torsion, to provide relative tension readings.

My thinking is that the "new" meter in the box is under the same stress as one that see's daily use. We're not cycling the spring in the TM-1 anywhere near it's limits. What- 50-100 times per day? Imagine a valve spring in a Nascar engine. If the spring won't last a lifetime without re-calibration... really? We need to talk to Park Tools.

So... Have you actually seen some change in calibration? What about the new one in the box?

mrrabbit 

They require calibration several time in a short period...then settle down? The TM-1 for daily use went through about 3 calibrations in the first 60-90 wheels maybe? Since then it has settled down. Haven't seen any changes in the last 100 wheels or so.

Like I stated earlier - spring based measuring tools typically require the most re-calibration. It's a function of wear and tear - in this case fatigue.

As I stated earlier, I don't use the new one in the box.

=8-)

eddy m

It sounds like the TM-1 is subject to a little break in wear. I'm guessing something with better build quality, like a DT Swiis Tensio or a Wheel Fanatyk, would have a lot less of that.
I made my own, using a weight to deflect the spoke. It's what an engineering undergraduate would come up with if you told he only needed to measure one wire. It's a lot harder to use than a TM-1, but it's less subject to friction and binding, It mostly avoids the calbration issues because I can calculate the tension from the deflection and weight. Maybe I should calibrate the dial indicator, but I'm not that anal.
FWIW worth if I thought I would ever build 3000 wheels I would get a Wheel Fanatyk gauge.

em

mrrabbit 

These fancy high end tensionmeters are overkill...whether I'm building 1 wheel or a 1000.

What I would really like is a bring back of the Wheelsmith - cause it's smaller I can use it in 20" wheels that have low flange hubs.

That's why I asked earlier about the size of the new entry on the market...

=8-)

FBinNY 

I have a few in stock, brand new in the box. email me using the link on the Chain-L site if you're interested.

eddy m

I like the Wheelsmith as well. It may not be much better than a TM-1, but at least it's a clever design. It surprises me that it was so much more expensive than something that looks like part of a Fisher-Price toolkit.
It's interesting that Rik Hjertberg designed the Wheelsmith, and now he is behind the Wheel Fanatyk tool, which was designed by Jobst Brandt.

em

mrrabbit 

Already have one...what I meant to say was bring it back - and a little smaller. I like the feel of the Wheelsmith tool construction-wise - doesn't feel cheap like the TM-1. I feel like one drop of the TM-1 and adios!

Sometimes I'm able to use it on a 20", sometimes like the TM-1 I'm not. Depends on hub and crossings...

=8-)

My current Wheelsmith is within the Park TM-1s +/- 3 kgf.

=8-)

Yan 

I have a Park TM-1. After using it for a while I realized that the reading varied depending on whether it was held horizontally or vertically. Apparently gravity had effect on how far the arm traveled before coming to a stop. Then I lubed it's moving parts with some discarded but still around White Lightning lube (which I'd sworn never to use again on a chain), and the readings jumped up 1.5 units across the board.

So much for accuracy. The point is, it's a nice tool for judging the uniformity of tension across all your spokes, not for absolute tension, which is approximate at best.

mrrabbit 

If you had bothered to read the included instructions in the box - or at the website, you would have known from day one that the tool is to be used in the horizontal plane.

No lube necessary, just a slight tap with an underside finger ensures it settles...

=8-)