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-   -   Wheel building, tension too high? (https://www.bikeforums.net/bicycle-mechanics/1008510-wheel-building-tension-too-high.html)

mooder 05-14-15 11:48 PM

Wheel building, tension too high?
 
Hey,

I have a high drive side tension 1.8mm round spoke indicate 24-25 on the park tool TM-1 which is 148 kgf for 24 and 167 for 25...!
The non drive side is going around 17-18 which is 70-77 kgf.

I am building the BDOP DIY allow kit and he recommend 110-115 on the drive side.


Originally Posted by Bob Dopolina (Post 17794221)
This is another topic that can become hotly debated. For a rider of your size I would shoot for around 95~100kgf on the front and 110~115kgf on the RR drive side. The RR NDS spokes will work themselves out.

These are based on recommendations from Sapim. The rims are fine with that, and more. The hubs don't have a limit (at least not one that has ever come up in 7+ years).

The wheel is nearly perfect in term of alignment (lateral and radial), it moves around 1mm at some places, the tension is pretty even on the NDS & DS. The hub is almost perfectly centered, a tad more tension on the driving side would bring the hub in the middle but the tension is already high...
I am just concerned with the tension. I compared the DS (drive side) tension with other rear wheels and it is very high. My R500 shimano have a 2.0mm round steel spokes and they hit 28 (173kgf).
I wonder if I should reduce the tension and if so how to properly adjust the wheel. Only way to reduce the DS tension is to reduce the NDS and it's already somewhat low...

3alarmer 05-15-15 12:29 AM


Originally Posted by mooder (Post 17806533)
Hey,

I have a high drive side tension 1.8mm round spoke indicate 24-25 on the park tool TM-1 which is 148 kgf for 24 and 167 for 25...!
The non drive side is going around 17-18 which is 70-77 kgf.

I am building the BDOP DIY allow kit and he recommend 110-115 on the drive side.



The wheel is nearly perfect in term of alignment (lateral and radial), it moves around 1mm at some places, the tension is pretty even on the NDS & DS. The hub is almost perfectly centered, a tad more tension on the driving side would bring the hub in the middle but the tension is already high...
I am just concerned with the tension. I compared the DS (drive side) tension with other rear wheels and it is very high. My R500 shimano have a 2.0mm round steel spokes and they hit 28 (173kgf).
I wonder if I should reduce the tension and if so how to properly adjust the wheel. Only way to reduce the DS tension is to reduce the NDS and it's already somewhat low...

...my own opinion (and it is based on what has worked well for me over the years), is that if you have the wheel tensioned at that level, and the rim is not deformed by the higher tension, it is fine, and in fact probably a stronger wheel in a lot of important ways. I would not personally lower the tensions if the rim is round (radially true), well dished in terms of centering, and true in one plane.

Someone else will doubtless now chime in and tell you that your wheeel will asplode at the higher tension. :)

Make sure you stress relieve the bends at the hub flanges, and you should be good to go.

Velocivixen 05-15-15 01:09 AM

My understanding is that you aim for tensions which are dictated by "the weakest link". You have rim, spokes and hub. All of those manufacturers would have tensions recommended for them. Pick the one with the lowest tension recommendation and use that as your guide.

dsaul 05-15-15 04:21 AM

At that tension, I would think you are going to see cracks around the drive side spoke holes in the rim fairly soon. I would lower the tension of the whole wheel.

FBinNY 05-15-15 04:39 AM

While I wouldn't have built to a tension that high, I wouldn't change anything now.

If I did anything, I might back off the tension about 5% as a form of stress relief, but that decision would rest on things like how hard nipples are to turn, how much spoke twist I was seeing, and if any nipples were start to round off from the wrench. If you go that route, do the left spokes first, so the rights are getting worked on at the lower tension.

The main issue with excess tension is rim stress, and the risk of premature stress cracking at the spoke holes. How much that's a concern depends on the rims, and the wall thickness at the holes.

The other issue is that overly tensioned wheels are more prone to becoming potato chips, and this risk depends on the lateral stiffness of the rim. Modern rims tend to be stiffer than years ago, so the risk isn't as high as it might be.

One of my key rules in wheel building is the same as in making bread ---Don't overwork the dough. This is why I opened with the suggestion to leave it as is unless you had a compelling reason to change it.

mooder 05-15-15 07:12 AM

Update: I lowered the tension, half a turn on all the spokes did the trick. The wheel is truer than ever! :)
This is somewhat weird, it's really easier to true it at higher tension and back off after. I wonder if the process straighten the rim? Now the DS is sitting at 105-117 kgf. I could bring the whole at ~117 with a bit more patience. The NDS is at 14-15 which is 58-64 kgf... I guess that will do!

Jiggle 05-15-15 08:07 AM

You should have inflated a tire on it and rechecked the tension. Also, the Park gauge usually reads a little high from the factory so your spokes were probably about 130kgf.

cale 05-15-15 08:41 AM


Originally Posted by FBinNY (Post 17806720)
While I wouldn't have built to a tension that high, I wouldn't change anything now.

If I did anything, I might back off the tension about 5% as a form of stress relief, but that decision would rest on things like how hard nipples are to turn, how much spoke twist I was seeing, and if any nipples were start to round off from the wrench. If you go that route, do the left spokes first, so the rights are getting worked on at the lower tension.

The main issue with excess tension is rim stress, and the risk of premature stress cracking at the spoke holes. How much that's a concern depends on the rims, and the wall thickness at the holes.

The other issue is that overly tensioned wheels are more prone to becoming potato chips, and this risk depends on the lateral stiffness of the rim. Modern rims tend to be stiffer than years ago, so the risk isn't as high as it might be.

One of my key rules in wheel building is the same as in making bread ---Don't overwork the dough. This is why I opened with the suggestion to leave it as is unless you had a compelling reason to change it.

I like your analogy.

FBinNY 05-15-15 11:42 AM


Originally Posted by mooder (Post 17806923)
....
This is somewhat weird, it's really easier to true it at higher tension and back off after. I wonder if the process straighten the rim?....

No, the rim itself isn't changed. But when you build a wheel, there;s lots of unsettled stuff, such as the set of the elbows, and the spokes aren't taking the dead straight path hub to rim. As you work with the wheel and bring up tension, all this is constantly settling in, changing the effective spoke length, and throwing the true off slightly, so you're trying to align a moving target.

Over tightening settled everything, so now you were truing a settled wheel which was easier. (it always is).

In the future, you can make truing easier by settling everything when the wheel is at about 80% of the desired final tension. There are a number of ways to do this, and whichever you prefer is fine.

You can grab both pairs of spokes at the crosses on opposite sides and squeeze toward center. Do this hard, so you're increasing the tension in these four. Do this once or twice going around the wheel. Or use a hammer or screwdriver handle, or a piece cut from a broomstick, and put it outside the cross, and push in and across toward the hub to move the cross down and stretch the spokes. This works great and is easier on the hands, but can be less effective for settling the outside elbows than the first method.

I'll often use both methods, the hand squeeze first to make sure the outside elbows are settled, then the broomstick when the wheel is nearly finished and true. If all is good, the broomstick doesn't change anything.

Al1943 05-15-15 01:05 PM

A lot depends on the strength of your rim and hub. When I built a wheel set with tensions that high (original post) the spoke holes in the hub flange wore very unevenly and the flange on the drive side eventually broke after 7 years. The rim was cracking at the spoke holes, but the hub flange failed first. I rebuilt the wheel with new identical hub and with stronger rim and lower tension, ~115 kgf drive side. I reused the old spokes and aluminum alloy nipples and still ride this wheel after another 4 years. All components are DT.

mooder 05-15-15 04:57 PM

Thanks guys for the replies. Putting the tire on the front dropped significantly the spoke tension! :(
I did not expect to be that much!

Bob Dopolina 05-15-15 05:43 PM

I was going to chime in but it seems like it's all been covered.

There will always be a drop in tension when tire/ tubes are installed and inflated. If you had a significant drop my first assumption would gave been spoke wind up which is dealt with through stress relief.

Get you tool back on there and bump the tension back up. The wheel is round and straight so you've already won that battle. The rest us just fine tuning.

Marcus_Ti 05-15-15 10:04 PM


Originally Posted by Bob Dopolina (Post 17808756)
I was going to chime in but it seems like it's all been covered.

There will always be a drop in tension when tire/ tubes are installed and inflated. If you had a significant drop my first assumption would gave been spoke wind up which is dealt with through stress relief.

Get you tool back on there and bump the tension back up. The wheel is round and straight so you've already won that battle. The rest us just fine tuning.

Depends how big the drop was.


Originally Posted by mooder (Post 17808653)
Thanks guys for the replies. Putting the tire on the front dropped significantly the spoke tension! :(
I did not expect to be that much!

It should drop it a bit with clinchers that is measurable but not much more than 0.5-1 index points on the Park tool IME....that being said running tubeless clinchers lowers the spoke tension a bit more than tubed clinchers. It happens and is normal.

Either way, unless there's a real need to worry about it....spokes popping....don't sweat it.


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