# Spoke Tension Calculator

I use this spreadsheet in the last step of a wheel build.  It converts spoke tension measurements from a Park Spoke Tension Meter into kilograms force (Kgf) and checks for tensions that are outside specified limits in absolute tension and variance in tension between spokes.  The tension limits can be edited.  The defaults are limits suggestion in the book The Art of Wheelbuilding by Gerd Schraner.  In my wheels (all 406), I make a few passes with the tension meter and spoke wrench to bring all spokes within the absolute tension limits and minimize the variance between spokes as much as possible.   But I give up long before all the variance numbers are within limits (there’s still plenty of red in the spreadsheet).  It’s possible that it’s easier to achieve these tolerances on a bigger wheel but I’ve never tried it.  Or that my calculations are off.  But I can say that I’ve never had a problem with a wheel built this way (I’ve re-trued maybe twice to correct very minor wobbles) so I’ve learned not to sweat it.

## 7 thoughts on “Spoke Tension Calculator”

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2. paul needham

Hi there

Love the spreadsheet , I think the tension is also related to spoke size ?

For plain spokes in SS I am using 14g [ 2mm ] will this table work ?

regards Paul

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1. Kurt Post author

Hi Paul,
I’ll have to take another look at the Art of Wheelbuilding reference I based this on, but I don’t think it considered spoke diameter for the tension recommendations. Of course there may be other, perhaps better limits out there, the spreadsheet lets you enter those if you don’t want the defaults. That said, 2mm spokes are what I’ve been using with these limits, with good results. FWIW over time I have gotten better with evening out the tensions using this spreadsheet, now I can usually get rid of most if not all of the red (indicating outside the limits). There does appear to be a bit of an “art” to this process…
kurt

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1. paul needham

Kurt

I build Python trikes and want to use SA hub brakes , however they come just as component parts and so need lacing into rims before they can be used.

Few wheel builders use 406 wheels so I was quite excited when I found your page.

I also tour , mainly Holland [ 5th time this year ] and this year trying to wean myself off trailer towing and carrying all my gear on the trike.

regards Paul

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3. Kurt Post author

Good luck Paul, I think you’ll find lacing your own wheels is quite doable and even enjoyable. I’ve had good luck with the SA drum hubs in the past.

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4. John

Hi kurt,
I’ve just starting spoke replacing and wheel straightening and have bought a parker spoke tensioner, have trouble finding out what tension to do the spokes upto as some hubs and rims have no manufacturer’s markings is there a chart that works using lengths, diameter and material of spokes?
Thanks
John

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1. Kurt Post author

Hi John,
That’s a good question. I came up with the tensions in the above spreadsheet based on some research and experimentation but now can’t find the source for these numbers. I know they work well for the 20″ Sun CR-18 rims I use. According to the Schraner Art of Wheelbuilding book, maximum spoke tensions are entirely determined by the quality of the rim, with double-wall and high-V rims capable of taking more tension. And you want the maximum tension the rim can support. As Schraner points out, you’ll strip the nipples or taco the wheel before breaking a spoke, so stop before that point :). I’ve had good success tensioning the spokes higher than I was initially comfortable, pretty close to the point that I’m stripping the threads in the nipples. I’m no expert, I highly recommend reading through Schraner’s book, it does a good job of quickly giving an idea of what you should focus on or worry about when building wheels.
Good luck,
kurt

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