[Bull_D]

just finishing my first "solo" wheel build......had some supervision on my first two sets. question for the pro's here.....how close can you expect to get your tension readings (using something like a park tension meter)? i assume a narrow range? unlikely to be exact on all spokes? some i know just use the "by hand" method, wondered if anyone accurately measures.

 

[CFoster]

depends in large part on the precision of the components...care to elaborate?

 

[Ratt]

just finishing my first "solo" wheel build......had some supervision on my first two sets. question for the pro's here.....how close can you expect to get your tension readings (using something like a park tension meter)? i assume a narrow range? unlikely to be exact on all spokes? some i know just use the "by hand" method, wondered if anyone accurately measures.

According to Park 20% of average is good. No pro here but I shoot for 5-10% but like Cfoster said it depends on the quality of the components.

 

[Bull_D]

by components i assume you are talking about the wheel parts and not the truing gear?
stans arch wheels, dt aerolites, king hubs. park TM-1 tension gauge.

 

[roger-m]

just finishing my first "solo" wheel build......had some supervision on my first two sets. question for the pro's here.....how close can you expect to get your tension readings (using something like a park tension meter)? i assume a narrow range? unlikely to be exact on all spokes? some i know just use the "by hand" method, wondered if anyone accurately measures.

I normally get them all to the same tension by plucking the spokes and this is very accurate. I may then put a tensiometer on just one or two spokes to test the actual tension. As an example I've just measured the spokes in the tight side of a rear and the tension range was 1250N to 1300N. Not sure on the math to work out what % this is.

There are other factors, you are attempting to get the rim true and round and with equal tension and obtaining this is sometimes not possible. My rim (above) was a DT 4.2D which is accurately made and I achieved true (lateral and round) and acceptable equal tension. Sometimes this is not possible and if the rim is not that well made you have to compromise and in this situation I favour equal tension but his might not be possible if the is rim being a PITA (yes some are).

Now here's another exaple for you. I've just had the opportunity to evaluate a brand new wheel built by one of the mailorder builders (UK), people are always raving about their wheels so I thought I'd take a closer look (Mavic 717 a well made rim). The wheel was laterally true but was not too round and the spoke tensions were all over the place yet people seem happy with their builds. The spokes were all wound up too. Whether they stay true is another matter but folks buy them and recommend them so I assume they work.

--
Roger

Edit for spelling mistake.

 

[dot]

Now here's another exaple for you. I've just had the opportunity to evaluate a brand new wheel built by one of the mailorder builders (UK), people are always raving about their wheels so I thought I'd take a closer look (Mavic 717 a well made rim). The wheel was laterally true but was not too round and the spoke tensions were all over the place yet people seem happy with their builds. The spokes were all wound up too. Whether they stay true is another matter but folks buy them and recommend them so I assume they work.

If you're talking about chain reaction cycles, their wheels are not very consistent in quality. I had a very good pair that withstood good beating off-road and a pair that needed truing after an easy road ride, different builders most probably.

 

[shiggy]

just finishing my first "solo" wheel build......had some supervision on my first two sets. question for the pro's here.....how close can you expect to get your tension readings (using something like a park tension meter)? i assume a narrow range? unlikely to be exact on all spokes? some i know just use the "by hand" method, wondered if anyone accurately measures.

I do use a Park meter and try to get the tension the same on all spokes (on the same side with dished wheels). I will except +\- 1/4 mark on the tool which is ~5%.

As long as all the rim and spokes are new the "quaility" should make little difference.

 

[Bull_D]

when dishing the wheel, you should expect to see a difference between the two sides?

 

[donkeyWC]

yes, if the hub is not for a zero dish wheel the tensions of the spokes on the drive side vs. the non drive side will be different.

 

[Bull_D]

how different would you expect? for instance, stans calls for a 100 KgF tension. the front (non-dished) is inside of 5% on all spokes. would you run the drive (dished) side above 100 and get the other side close, or run the drive side at 100 and the other side lower?

 

[shiggy]

how different would you expect? for instance, stans calls for a 100 KgF tension. the front (non-dished) is inside of 5% on all spokes. would you run the drive (dished) side above 100 and get the other side close, or run the drive side at 100 and the other side lower?

You run maximum tension on the dished side (drive side rear, disc side front) and the tension for the other side is what it needs to be to have the rim centered properly. How much side to side difference there is depends on the hub and, to a lesser degree, spoke lacing pattern, used.

I am reluctant to use Stans rims because of the low tension limits.

 

[donkeyWC]

when using tensiometers such as park and the dt swiss these tensiometers depend on spoke diameter and measure directly the deflection under the applied load of the spring in the tensiometer. this deflection value gets you into the deflection-tension chart for that diameter of spoke measured and gives a tension value.

there are manufacturing tolerances on spoke diameters which yield a distribution of spoke diameters for a given spoke type. for example a 14/15 ga. double butted spoke at nominal dimensions is 2.0/1.8/2.0 mm in diameter. manufacturing could yield a spoke that is 1.93/1.76/2.02 mm, or whatever. usually the range is fairly small (~5% within nominal) if using spokes of high quality and can be verified on your own wheel's spokes with a good set of calipers. however, this small variance in spoke diameters will yield errors in measured tension values as the charts are designed for nominal values. you can correct for that if you measure the spokes and then interpolate between chart values...this is tedious and is completely unnecessary to build a great wheel. this manufacturing variance in spoke diameters is one part of a tensiometer's error range for measuring spoke tensions. other errors arise from a nonlinear spoke path from hub to rim (dependent upon lacing pattern) and where the tensiometer is placed on the spoke (similar concept to variance in diameter).

 

[roger-m]

when using tensiometers such as park and the dt swiss these tensiometers depend on spoke diameter and measure directly the deflection under the applied load of the spring in the tensiometer. this deflection value gets you into the deflection-tension chart for that diameter of spoke measured and gives a tension value.

there are manufacturing tolerances on spoke diameters which yield a distribution of spoke diameters for a given spoke type. for example a 14/15 ga. double butted spoke at nominal dimensions is 2.0/1.8/2.0 mm in diameter. manufacturing could yield a spoke that is 1.93/1.76/2.02 mm, or whatever. usually the range is fairly small (~5% within nominal) if using spokes of high quality and can be verified on your own wheel's spokes with a good set of calipers. however, this small variance in spoke diameters will yield errors in measured tension values as the charts are designed for nominal values. you can correct for that if you measure the spokes and then interpolate between chart values...this is tedious and is completely unnecessary to build a great wheel. this manufacturing variance in spoke diameters is one part of a tensiometer's error range for measuring spoke tensions. other errors arise from a nonlinear spoke path from hub to rim (dependent upon lacing pattern) and where the tensiometer is placed on the spoke (similar concept to variance in diameter).

100% true!

I use DT spokes.

When a box of my spokes is getting low I don't just open a new one and toss the remainder of the old box into them. I first get the micrometer on them to make sure they are both the same diameter. It makes it slightly less of a headache when checking spoke tension. I'm getting to the stage where for the same length I often have two boxes with different diameters.

The solution that you forgot to mention is to use the FSA tensiometer which you have pictured in another of your posts. This does not rely on spoke diameter.

http://forums.mtbr.com/showpost.php?p=4635165&postcount=2

Your post is very precise about the problem with existing tensiometers. Are you connected to FSA and Ric H?

--
Roger

 

[donkeyWC]

no, i'm not connected to fsa. i'm just a mechanical engineer that likes to geek out on certain things and i took a hard look at tensiometers a while back when i was in the market to buy one.

yeah, the fsa tensiometer comes with a much simpler conversion table and handles manufacturing tolerances better; it still gives a +/-10% error due to some of the things i mentioned above though. for standard round spokes the fsa chart has only two groups (group 1: 2.3 - 2.0mm & group 2: 1.8 - 1.5mm; giving each group a range of 0.3mm in dia.) which makes it very convenient for converting deflection readings to tensions. they (fsa) are taking advantage of a small angle approximation which states sine x = x, where x is the angle of deflection measured in radians. the approximation is valid because the deflection of the spoke is very small with the fsa tensiometer. this is also what allows the diameter of the spoke to play less of a role in the tension measurement. whereas in the tensiometers previously mentioned the magnitude of deflection is great enough that the section must be accounted for as its resistance to bending will affect the reading and hence the need for more extensive conversion tables.

cheers.

 

[Bull_D]

holy schnikees!! i didn't know wheel making was rocket science!!
thanks for the input. we will have to see how they hold up.

 

[donkeyWC]

it's not unless you want it to be. i'd also be the first to admit that wheel builders not interested in the physics, but with more experience than me could probably build a better wheel than me as i only build a few wheels for friends, my wife, and myself.

 

[roger-m]

holy schnikees!! i didn't know wheel making was rocket science!!
thanks for the input. we will have to see how they hold up.

It's not rocket science, it's just that a few of us like to explore the finer details.

Is a 100% perfect wheel better than an acceptably good one? No, and you are all capable of building a good wheel, certainly better than the many examples I come across.

Your wheel will hold up, it's not going to fold and pitch you off into the weeds.

--
Roger

 

[Bull_D]

.....yeah, i was just foolin'. one day i was at my dad's (former marine) with my brother and cousin having thanksgiving dinner. we started joking about a slight anal retentive thread that MIGHT run through the males in the clan. i think he thought it was some homosexual reference:madman: , but his exact quote was "well, i don't know about that.....but i do know that no job can be done too perfect."..........we pissed ourselves laughing. so i know where the "geeking" comes from. probably why i asked the question. the fact that the wheel was sweet round and true wasn't completely satisfying since all the tensions didn't match:nono: . anyway, rode today and the wheels did NOT fall off! not sure about the "too perfect" part, but i think most guys i know that work on most of their own stuff (bikes, cars, whatever) do pay attention to detail. thanks for the info (and the engineering lesson!):eekster:

 

[RSW42]

According to Park 20% of average is good. No pro here but I shoot for 5-10% but like Cfoster said it depends on the quality of the components.

Concur with Ratt...

Remember, a good STRONG set of wheels is all about uniformity...

Park recommends 20%, but I too shoot for 5%...

Plus, I'm just super anal-retentive when I build any wheels

.