spoke tension question

[bitt3n]

How do I know what spoke tension I should be aiming for if I'm using a HED Belgium Plus Rim and Sapim Race round 1.8mm spokes?

I managed to get my wheels dished and trued to within about a 0.25 mm both horizontally and vertically but I think the spoke tension is way too high at 170 KGF on the drive side and 100 KGF on the disc side on the rear wheel and 150 KGF disc and 100 KGF non-disc side for the front (according to the Park TM-1 and Park Wheel-Truing App).

Also there's considerable variation between the tensions of spokes on the same side of the same wheel, which I imagine is a sign of incompetent wheel building.. It looks like I need to get them within 20% of one another?

[ergott]

Too high. Use 120 drive side (left is whatever it is to get rim centered) and 100-110 front.

Make sure you are consistent with how you use the Park tensiometer. I'd try to keep all the spokes closer to 5-10% variation.

[bitt3n]

Too high. Use 120 drive side (left is whatever it is to get rim centered) and 100-110 front.

Make sure you are consistent with how you use the Park tensiometer. I'd try to keep all the spokes closer to 5-10% variation.

10% seems rather close to the tolerance of the TM-1 tensiometer. For my spokes, a reading of 22 corresponds to 117 KGF and 23 corresponds to 131 KGF, which is roughly 12% more. I guess I'll try to keep all the drive-side spokes between 22 and 23.

In retrospect I guess I should have built my wheels by slightly tensioning all the spokes, then tensioning the drive-side to ~120 KGF while adjusting the non-drive side so that the wheel stays true/dished. Is that more or less the way you do it?

[classtimesailer]

Yes. Round and round we go. Little by little. Checking dish and trueness along the way. And then all is good. I'm not a pro but it seems to me that plucking spokes is a credible guide to even tension and works as well as my TM-1.
Roger Musson's ebook is highly recommended.

[foo_fighter]

I'm a bit surprised you were able to get upto 170Kgf. Brass nipples and good 3 sided spoke wrench?

[sales guy]

If you went high tension and did it quickly and not gradually on both sides, you could've broken the backbone of the rim. If that happens, they'll never stay straight or tensioned.

You need to bring the tensions up gradually on both sides at the same time. It makes it easier to dish and keep the hops and flat spots minimal if any(until you do those specifically) and it also keeps the rim from warping.

We had someone at AMC who would just jack the tension up and his wheels never held. They would always come back for rebuilds. We tasked him to do 10 wheels once for a bike company for review to see about OEM use. Of the 10, 1 was spot on, the other 9 were all off. Tensions. Up and down, side to side. He actually told us he wanted to be paid to fix the problems. That he was paid to just build them. NOT to fix the problems. We were like ***??? He ended up getting let go and I had to redo all 10.

Slow and steady wins this race.

[bitt3n]

I'm a bit surprised you were able to get upto 170Kgf. Brass nipples and good 3 sided spoke wrench?

aluminum nipples lubricated with linseed oil and a cheap spoke wrench.

If you went high tension and did it quickly and not gradually on both sides, you could've broken the backbone of the rim. If that happens, they'll never stay straight or tensioned.

You need to bring the tensions up gradually on both sides at the same time.

I increased the tension only gradually over the course of truing/dishing but it appears I ought to have paid more attention to how much tension I was applying. My tension was way to high and there was way too much variation between the tension of different spokes.

I've seen a bunch of videos of people building wheels without using a tensiometer so I figured it wasn't that vital but Ergot's suggestion tells me that the tension needs to be attended to more carefully than I realized.

[R3awak3n]

the park tool apparently reads very conservatively so you probably did not have 170kgf on that wheel and why it didnt brake anything because that is a crap load of tension.

[oldpotatoe]

aluminum nipples lubricated with linseed oil and a cheap spoke wrench.



I increased the tension only gradually over the course of truing/dishing but it appears I ought to have paid more attention to how much tension I was applying. My tension was way to high and there was way too much variation between the tension of different spokes.

I've seen a bunch of videos of people building wheels without using a tensiometer so I figured it wasn't that vital but Ergot's suggestion tells me that the tension needs to be attended to more carefully than I realized.

Agree with ERGOTT and altho the Park tool is a decent consumer tool, the Wheelsmith one is more accurate. People who use 'c above middle F' type stuff for wheels make me scratch my head. Or those who say their 'hands' can feel proper tension..the path to poor wheels, IMHO.

Proper and even tension, along with the other 3 variables being proper, at the same time=long lasting wheels.

[staggerwing]

the park tool apparently reads very conservatively so you probably did not have 170kgf on that wheel and why it didnt brake anything because that is a crap load of tension.

This is NOT what I found with my Park tension meter. Built a calibration fixture (dead weight/lever arm), and found it read 2-4% low over a variety of spokes, from 2.0mm straight gage, 1.8mm swaged, and aero bladed (CX ray) spokes.

Pretty darned good for a simple device.

Relative pitch can be useful for finding an outlier. However, I couldn't possibly tell what the proper pitch for a specific tension would be.

[ColonelJLloyd]

That's pretty damned high. If it were me I'd start over with new nipples.

[Hindmost]

aluminum nipples lubricated with linseed oil and a cheap spoke wrench.

I am surprised the nipples didn't visibly deform.

[11.4]

For any particular rim there's a particular tension where everything settles in very nicely. Below that tension, you won't get consistent spoke tension; go much above that tension, and you'll have that problem again. When you reach the right tension you should be able to get about 3% variance or less per spoke, and I've seen people do better than that -- after stress relieving. That's the kind of consistency that leads to the longest-lived and most problem-free wheels.

While someone may say that there's an arbitrary tension to reach, you'll find that one rim may consistently have a certain optimal tension but it can be higher or lower than another rim. The Hed Belgium is an incredibly strong rim and not only is likely to true ideally at a slightly higher tension, but it also can explain why you didn't run into problems with excessive tension.

[bitt3n]

For any particular rim there's a particular tension where everything settles in very nicely. Below that tension, you won't get consistent spoke tension; go much above that tension, and you'll have that problem again. When you reach the right tension you should be able to get about 3% variance or less per spoke, and I've seen people do better than that -- after stress relieving. That's the kind of consistency that leads to the longest-lived and most problem-free wheels.

While someone may say that there's an arbitrary tension to reach, you'll find that one rim may consistently have a certain optimal tension but it can be higher or lower than another rim. The Hed Belgium is an incredibly strong rim and not only is likely to true ideally at a slightly higher tension, but it also can explain why you didn't run into problems with excessive tension.

Is there a good resource for getting the optimal spoke tension for a given rim? I tried searching for HED Belgium Plus and all I found was some guy on bikeforums (http://www.bikeforums.net/bicycle-mechanics/992050-hed-belgium-rim-163kgf.html) claiming he read on some other guy's blog and it said the max acceptable spoke tension for this rim is 163 KGF..

[11.4]

Is there a good resource for getting the optimal spoke tension for a given rim? I tried searching for HED Belgium Plus and all I found was some guy on bikeforums (http://www.bikeforums.net/bicycle-mechanics/992050-hed-belgium-rim-163kgf.html) claiming he read on some other guy's blog and it said the max acceptable spoke tension for this rim is 163 KGF..

Not really. Individual lacing methods, choice of spokes, even different batches of spokes, can bring about differences.

Don't bother with BikeForums. Their information is so suspect as to be useless. And anyway, even an acceptable spoke tension of 163 kgf doesn't say much about how the rim will respond or what you actually did to the rim. These are brutally tough rims and about the best that you could have chosen to learn on.

You'll find that with most tensiometers, there can be 10% or even 20% inaccuracy in measurement. The better ones are at least consistent spoke to spoke. If you use the DT one, which is the most accurate and the most reproducible in my experience, you'll find that if you gradually up the tension as you get close, with repeated stress relievings, you'll find that after relieving you end up with scattered variances and then get to where you're bang on target on virtually every spoke. You may have a glitch in any rim that causes one spoke to be off a bit, but if it's just one spoke that measures low and the wheel is still round, try tightening that spoke up to match the tension of the others. The stress will distribute itself much more effectively when the rim is at the right tension, and that makes the wheel building much easier and also makes for a much better wheel.

It's important to stress relieve adequately. Most people don't begin to do so enough, which is why their wheels move a bit with use. I've heard people object to approaches that really mash the wheel but frankly, I've seen relieving improve the wheel and remove issues in just about every instance with modern rims. With a rim like the Belgium, in a reasonably dense spoking, I don't hesitate to lay it on its side and put some pressure on the spoke crossing to force a flexing. Or to use a 1" dowel to twist and flex the spokes significantly. We build hundreds of track wheels and I don't think we've ever had to retrue one, despite banking stresses, high tire pressures, the nature of the events themselves, and periodic crashes. I'd never do this with older style rims, but new style rims are designed to be self-supporting and don't rely on the spoking for stability. Ditto for most carbon rims.

[bitt3n]

It's important to stress relieve adequately. Most people don't begin to do so enough, which is why their wheels move a bit with use. I've heard people object to approaches that really mash the wheel but frankly, I've seen relieving improve the wheel and remove issues in just about every instance with modern rims. With a rim like the Belgium, in a reasonably dense spoking, I don't hesitate to lay it on its side and put some pressure on the spoke crossing to force a flexing. Or to use a 1" dowel to twist and flex the spokes significantly. We build hundreds of track wheels and I don't think we've ever had to retrue one, despite banking stresses, high tire pressures, the nature of the events themselves, and periodic crashes. I'd never do this with older style rims, but new style rims are designed to be self-supporting and don't rely on the spoking for stability. Ditto for most carbon rims.

Hm I haven't detensioned the wheel at all. Is this video (https://www.youtube.com/watch?v=Zeyr-brECm4) a good example of detensioning a wheel? Basically he just puts it on a bench and rotates it, leaning his weight on the rim, then flips it over.

That DT tool looks great but at $500 I think I'm stuck with the TM-1.

[Black Dog]

Here is a good and detailed resource for wheel building. http://miketechinfo.com/new-tech-wheels-tires.htm#Wheelbuilding

[ergott]

Hm I haven't detensioned the wheel at all. Is this video (https://www.youtube.com/watch?v=Zeyr-brECm4) a good example of stress relieving a wheel? Basically he just puts it on a bench and rotates it, leaning his weight on the rim, then flips it over.

That DT tool looks great but at $500 I think I'm stuck with the TM-1.

His first method potentially damages the bearings in the hub. You are putting loads on the wheel that the hub wasn't designed for.

Method two is fine, many builders do it.

I grab spoke pairs as described by Brandt. The wheel is still in the stand and I have two parallel spokes from the right side in my right hand, and same on the left side. Grab really hard and on to the next pair. For radial same, just two adjacent spokes.

Stress relieving the spokes is often a misunderstood practice. This article does the best to explain why it is done.
https://sheldonbrown.com/brandt/stress-relieving.html

When I build, I am bringing up tension 1-2 turns at a time the first couple go arounds. Then I start correcting the spoke path using a drum stick and the plastic handle of a small hammer. This is not stress relieving yet.

I continue bringing up the tension while trying to keep the spoke tension relatively uniform and the rim true. As I get closer to the desired tension, I start the stress relieving mentioned above. Every wheel gets a minimum of 3 sessions. You seen large drops in tension the first time or two. After that, tension starts to level out and stay put no matter how many times you go around the wheel. Then just do the finishing touches to truing the wheel.

[ergott]

The Park and Wheelsmith tensiometers can be great. Biggest issue is calibration. How you release the spring tension of the tensiometer as you get a reading on the spoke can really change your results. In an ideal situation you would calibrate the tool using your feel for the tool.

I built a calibration rig to keep my FSA tensiometer in check. It's also good to do a calibration run with each new spoke brand/model so your results are consistent. I have a chart for each spoke I use in 10kg intervals starting around 50kgf up to 130kgf. I don't build any wheels to tensions above that, there's really no point. The two weakest links are hub flanges (not only radial lacing) and the rims' nipple bed. The spokes and nipples aren't close to their yield in any wheel.

[Mark McM]

Is there a good resource for getting the optimal spoke tension for a given rim? I tried searching for HED Belgium Plus and all I found was some guy on bikeforums (http://www.bikeforums.net/bicycle-mechanics/992050-hed-belgium-rim-163kgf.html) claiming he read on some other guy's blog and it said the max acceptable spoke tension for this rim is 163 KGF..

Sadly, the rim manufacturers typically don't give much guidance on appropriate spoke tension. I don't understand why this is, as spoke tension is mostly governed by the rim and the number of spokes (which is also governed by the number of spoke holes in the rim).

Jobst Brandt recommended using the highest tension the rim could bear, and gave a method to findng that tension in his book, "The Bicycle Wheel". However, this book was written when wheels used more spokes than are typically used today (Brandt's wheels typically had 32 or more spokes), so Brandt's method may not be applicable to wheels with fewer spokes.

After using the Brandt method a number of times, I've found that the appropriate spoke tension for modern aluminum rims typically correlates to the weight of the rim and the number spokes according to the following relationship:

Tension = (Rim Tension Coefficient) x (Weight of rim in grams) / (Number of spokes)

The Rim Tension Coefficient can vary, largely depending on the rim material (alloy and temper), but is typically in the range of 8 - 9 kgf-spokes/gram.
So, for example, a 425 gram Open Pro rim would use the following average tensions:

For 28 spokes: Tension = ( 8 kgf-spokes/gram) x (425 grams) / (28 spokes) = 121 kgf

For 32 spokes: Tension = ( 8 kgf-spokes/gram) x (425 grams) / (32 spokes) = 106 kgf

For 36 spokes: Tension = ( 8 kgf-spokes/gram) x (425 grams) / (32 spokes) = 94 kgf

(Note: The above recommendations are average tensions - for dished wheels, the drive side may use more and the non-driveside may use less.)

Rims with fewer spokes generally need more tension than rims with more spokes, but the allowable tension is generally less than what the simple formula above predicts for rims with many spokes. Also, the formula may predict excessive tensions for very heavy rims. However, the formula tends to work well for rims of 500 grams or less and for 28 spokes or more.

In any case, the recommendations made in this thread of never exceeding 120 kgf does not agree with the specifications of many manufacturers of low spoke count wheels, who sometimes allow as high as 180 kgf. Some manufacturer's recommendations can be found at the Park web site:

http://www.parktool.com/blog/repair-help/#article-section-6

Some of Campagnolo's recommendations are here:

http://www.campagnolo-sirer.cz/img/cms/N%C3%A1vody%20k%20pouziti/PREDPETI%20DRATU%20ZAPLETENYCH%20KOL_2015-2016.pdf

And some of Mavic's recommendations are here:

https://tech.mavic.com/tech-mavic/technical_manual/data/docs/themes/2_19.pdf

Note that according to Campagnolo's and Mavic's recommendations, if the drive side tensions were even as high as 120 kgf, that would still be lower than the minimum recommended tension for certain wheels.

Personally, I have used average tensions as high as 150 -160 kgf on 16 to 20 spoke front wheels and on the drive-side of 20 to 24 spoke rear wheels (depending on the rim), and not had any problems with the wheels remaining straight and true, or in breaking spokes or cracking rims.