Improving my rubbish Spoke Tension meter ?

Joined
Feb 7, 2008
Messages
2,651
Location
Nottinghamshire England
Hi all

I am considering how to improve my rubbish Spoke Tension meter :-



It had no bad reviews and was half the price of the Park Tools one what could go wrong ?

So all these meters come with a conversion table for different spoke types [ mine is currently MIA and I can't find one on the net ]

Luckly I had made a table up for it using 2mm spokes and found the figures also for the Park Tools one on the net.

17
50.0
52
18
51.0
59
19
51.5
64
20
52.0
68
52.5
73
21
53.0
77
53.5
82
22
54.0
87
23
54.5
94
55.0
100

So Park on left mine in middle and Kgf

Park gauge table starts at 17 on mine 50 and reads 52 Kgf

Now further down

Park gauge we are now between 23 and 24 mine 55 and reads 100 Kgf

Now all the work to get the wheel tensioned and normalised lies between these readings

On my gauge there are 5 divisions between 50 and 55 , however 50 and 55 are 3mm apart ! you have got to be kidding me !!!

So how the hell are you supposed to measure the 8 readings they show in the table in 3mm ?

On the park there is about 16mm between 17 and 24 look how uncluttered the scale is compared to mine ?


I wondered if I could get a reference tension/Kgf I could slacken off the tension of my spring and widen the scale of the readings by making it read less ?

In other words if the max mine could read was say 100 kgf that might expand the scale towards 0 giving me better resolution in the area of forces I want to measure ?

frustrated does not come close !!!
 
Joined
Oct 19, 2012
Messages
896
Location
Wakefield, UK
Don't you need to make it over-read rather than under-read? ie a true reading of 50 needs to show 100 or so? You're right in wanting to slacken spring tension, but that would make it read more by suckering it into thinking the spoke is more tensioned than it is.
 
Joined
Feb 7, 2008
Messages
2,651
Location
Nottinghamshire England
Don't you need to make it over-read rather than under-read? ie a true reading of 50 needs to show 100 or so? You're right in wanting to slacken spring tension, but that would make it read more by suckering it into thinking the spoke is more tensioned than it is.
unsure that is why I am asking on here :LOL:

The gauge currently has a scale reading from 0 to 135
First problem is there are no spokes that use a number under 21 , meaning 21 graduations not used at low end
Second problem is there are no spokes that use a number higher than 70 , meaning 64 graduations not used at high end
third problem is that for a 2mm spoke the only graduations used are between 48 and 59 meaning 11 graduations for Kgf between 41 and 170 !

So each graduation for a 2mm spoke equals approx 11 Kgf and those 11 graduations are in approx 10 mm

So for a 2mm spoke I am using 8% of the total scale !

so looking at a simplified version of the scale

graduation_ 0-----------------------------------50---55--------------------------------------------------------135
_____Kgf__0------------------------------------50--100

What I need is more like this
graduation_0-----------------------------------50-------------------------------------------------------------135
_____Kgf__0-----------------------------------50--------------------------------100-------------------------135

Admittedly it will then only do 2mm spokes , however I can live with that

So for it to read the higher values 170 Kgf surely the spring has to be stronger ? so if I lessen the spring value I should spread the available range over more graduations but sacrifice any top end ?

Still need to find a way of test it before I try to alter it.

Oh and the above maths may be suspect - please tell me if I have goofed [ but no sniggering ]

regards Paul

PS the Park Tool reads 17 - 28 so 11 steps as above however the scale is only 0 - 45 so those 11 steps are 25% about 20mm of the width NOT my paltry 8%
 
Last edited:
Joined
Oct 19, 2012
Messages
896
Location
Wakefield, UK
I don't have a spoke tensionometer so I'm only going on how I think they work rather than any reality. Correct me if I'm wrong but the spoke is trapped between the three bolts and the middle one is on a spring which tries to bend the spoke which gives a reading. The more it bends the less the spoke tension. If I've got that right the stronger the spring pushing the middle bolt the lower the reading will be as it can bend the spoke more. The weaker the spring the harder it thinks the spoke is tensioned. You need to get higher readings using more of the scale for a set spoke and therefore need a weaker spring. As to how much tension to take off that'll proably be trial and error. It may not be a linear relationship. Even if the scale is pants it has to be more useful than giving the spokes a tug to test them like I do.
 
Joined
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Messages
2,651
Location
Nottinghamshire England
Popshot

You may have a spoke tension meter sooner than you think.....
PM me an address and it will be on it's way to you.....

What do I want in return ?
Just come on here and give an honest appraisal of it ?

Fair ?
 
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