Spoke tension - is there such a thing as too much?

TurnerConvert · Jan 7, 2008

I just finished building my first wheel this morning using DT Swiss EX5.1d rims with Competition spokes. During the build process I equalized all of the spoke tensions using the pitch technique (that worked amazingly well!), and then finally at the very end actually checked the spoke tension using a park tensiometer.

The good news is that all of my spokes are within +/- 2% of each other on each side of the wheel. The potential bad news is that one side of the wheel had a reading on my tool of 23 and the other side had a reading of 26. I measured in the narrower part of the spoke, so based on the included chart this means that my spoke tensions are 124 Kgf and 176 Kgf. According to DT Swiss the max tension for the rim is 120 Kgf.

So the first question: is this chart accurate for DT Swiss competition spokes, or are there charts that I cannot find that are specific to a manufactured spoke?

Second question: do I need to back off the tension on the entire wheel, or is it OK to keep the spoke tension as high as I have it?

coelhomd · Jan 7, 2008

Imagine that if there is much tension difference all around the circumference of your rim, there will be points subject to more stress, this is an unstable rim.

It is good to have a wheel with evenly tensioned spokes. Truing lasts much longer, as well as rim's life.

dan0 · Jan 7, 2008

too much tension can pull the nipples so hard that the rim holes distort and pull out

Circlip · Jan 7, 2008

If you managed to complete the build without the wheel tacoing, and if none of the components fail during your use of the wheel then it's not too much tension. Of course, if you don't want to find out through trial and error, then you're probably better off to get a little closer to recommended tension specifications. Most components will hold at least a bit more tension than rated for though. As you can imagine, the recommendations are a bit on the conservative side, as opposed to pushing the envelope.

FM · Jan 7, 2008

Too much tension can screw with the tolerances inside the hub shell. I've seen a few hubs that were laced up too tight and the press-fit sealed bearings just fall out of the hub shell.

Obviously too much tension can cause spokes to fail at the elbows as well.

roger-m · Jan 7, 2008

TurnerConvert said:
I just finished building my first wheel ...

The potential bad news is that one side of the wheel had a reading on my tool of 23 and the other side had a reading of 26.

A dished wheel (rear wheel or front disc brake) will have different tensions. Take your readings from the tight side and the other side is whatever it happens to be.

I measured in the narrower part of the spoke, so based on the included chart this means that my spoke tensions are 124 Kgf and 176 Kgf. According to DT Swiss the max tension for the rim is 120 Kgf.

I very much doubt you've tightened them to 176kg, that's extremely tight and would be difficult to do. Make sure the tensiometer is functioning okay and that you are reading the correct calibration tables (although I'm not familiar with the operation of the Park tensiometer).

Second question: do I need to back off the tension on the entire wheel, or is it OK to keep the spoke tension as high as I have it?

Make sure you get an accurate reading before touching the tensions. If it is 176kg then that's a bit high and would need backing off, but my guess is that you are nowhere near that.

--
Roger

Bubba74 · Jan 7, 2008

roger-m said:
If it is 176kg then that's a bit high and would need backing off, but my guess is that you are nowhere near that.Roger

I have the exact same setup as the OP and I had spoke tensions in that range (reading 26 on the park tool). It wasn't that hard to achieve, in fact with antiseize and lube on the nipple seats, I could have tightened them further without too much effort.

I'm still curious about the how high to tension the spokes though. Right now I have max tension to what the rim recommends (120 Kgf), but I read alot of people posting here running tensions higher than that....

TurnerConvert · Jan 7, 2008

I didn't word the part of my post about the different spoke tensions too well - I was fine with the different tensions on the drive side and the non-drive side spokes being different; it was just the absolute tension that had me worried.

roger-m said:
I very much doubt you've tightened them to 176kg, that's extremely tight and would be difficult to do. Make sure the tensiometer is functioning okay and that you are reading the correct calibration tables (although I'm not familiar with the operation of the Park tensiometer).

Make sure you get an accurate reading before touching the tensions. If it is 176kg then that's a bit high and would need backing off, but my guess is that you are nowhere near that.

I'm reasonably confident that I am using the park tool correctly. Here's a link to Park's online chart if anyone wants to verify that I'm doing the conversion correctly:TM-1 Tension Meter Conversion Table My readings were 26 and 23. In comparing the tension to other wheels that I have that were built by reputable builders, the spoke tension is definitely higher on my wheel than on those. Let's just say that there isn't much give when I squeeze on parallel spokes around the wheel.

I ended up with such high tensions for two reasons:
1) I think I dished the wheel a little later than I should have, and I adjusted the dish mostly by tightening spokes on the one side instead of loosening spokes on the other

2) When I was equalizing spoke tensions, I kept adjusting all spokes to the spoke with the highest pitch. I would have been well served to check the absolute tension at intermediate points instead of waiting until the very end.

Before I adjust the tension backwards, I'll make sure that I have used the tensiometer correctly. I'd hate to undo a perfectly good wheel. Thanks for all of the input.

JMH · Jan 7, 2008

TurnerConvert said:
Before I adjust the tension backwards, I'll make sure that I have used the tensiometer correctly. I'd hate to undo a perfectly good wheel. Thanks for all of the input.

It's no big deal... start with the drive side, back each nipple off 1/2 turn. Now do the non-drive side the same amount (well, a bit more than 1/2 turn to compensate for dish/tension.

Check the tension, repeat as necessary. When you hit a good tension, true and dish.

If you back the nipples off equally, the wheel will stay remarkably true/round, and you won't be undoing anything.

JMH

bad mechanic · Jan 7, 2008

Just making sure, you're using 2.0/1.8/2.0 DT Swiss Comp spokes and not 2.0 DT Swiss Champion spokes? Can you feel where the spokes become narrower? If they are indeed Comps, then you should reduce tension on them. 175kgf is just too much and can lead to a self destructing wheel. Personally I think 120 is too low for modern wheels and equalize mine between 130 and 140.

To reduce tension just go all the way around the wheel and loosen each spoke a quarter turn. Two trips all the way around should get you to a reading of about 24, which is 138kgf.

Ratt · Jan 8, 2008

bad mechanic said:
....Personally I think 120 is too low for modern wheels ....

Stans recommends between 85 and 100kg on their modern rims and dt swiss specifies 120 max.

bad mechanic · Jan 8, 2008

Ratt said:
Stans recommends between 85 and 100kg on their modern rims and dt swiss specifies 120 max.

Stans recommends tension that low because they don't use eyelets so their rims aren't able to withstand high spoke tensions.

I feel every major rim manufacturer rates their rims low. For a while I tried setting the tension around 110-120, but raising it to 130-140 did nothing but increase the life span of my wheels and decrease the amount I had to true them.

TurnerConvert · Jan 8, 2008

So I retensioned the wheel last night. It took longer than I expected - it almost felt as though the spokes had 'set' and every spoke seemed to wind-up before releasing each time I tried to adjust the tension. But in the end I was able to get the wheel laterally true and the spoke tension equalized on each side of the wheel again, so it should be good to go. Definitely a useful learning experience if nothing else

Now to get a tire mounted on it. I have a new Schwalbe Albert UST that I spent an hour trying to get on and couldn't do it. A WTB Weirwolf 2.5 that I had previously used went on with no problems, but I really want to run this wheel tubeless. If its not one thing its another....

Bubba74 · Jan 8, 2008

bad mechanic said:
I feel every major rim manufacturer rates their rims low. For a while I tried setting the tension around 110-120, but raising it to 130-140 did nothing but increase the life span of my wheels and decrease the amount I had to true them.

My average tension on the drive-side is around 130-135, but I have like 2 spokes that are 150 to retain true. Should I back out ALL the tensions to bring these two spokes down? I'm just concerned that the average tension will be lower than I would like to keep these 2 spokes to acceptable limits.

TurnerConvert · Jan 8, 2008

Bubba74 said:
My average tension on the drive-side is around 130-135, but I have like 2 spokes that are 150 to retain true. Should I back out ALL the tensions to bring these two spokes down? I'm just concerned that the average tension will be lower than I would like to keep these 2 spokes to acceptable limits.

Since I just finished my first wheel, take this for what it is worth. I found that if I went around the wheel twice equalizing the spoke tension (once round for drive side and once round for non-drive side), stressed the wheel to relieve and spoke wind-up and then went back around again to true the wheel laterally, that everything actually came out pretty close. I did this sequence 2-3 times and finished with equalizing the spokes since this seems more important than minor variations in trueness. With my few hours of experience, I'd recommend backing off those two spokes that are high and try making minor adjustments. FWIW the plucking method to determine relative tension definitely speeds up the process of equalizing spoke tension.

Bubba74 · Jan 8, 2008

TurnerConvert said:
Since I just finished my first wheel, take this for what it is worth. I found that if I went around the wheel twice equalizing the spoke tension (once round for drive side and once round for non-drive side), stressed the wheel to relieve and spoke wind-up and then went back around again to true the wheel laterally, that everything actually came out pretty close. I did this sequence 2-3 times and finished with equalizing the spokes since this seems more important than minor variations in trueness. With my few hours of experience, I'd recommend backing off those two spokes that are high and try making minor adjustments. FWIW the plucking method to determine relative tension definitely speeds up the process of equalizing spoke tension.

I probably did the same process you did like 6-8 times lol. I know...I need a life

If I lower the two spokes, the wheel goes out of true, albeit a minor amount. Plucking worked very well. I would say my tones are all really close, and I'm a musician so I trust my ear

TurnerConvert · Jan 8, 2008

Bubba74 said:
I probably did the same process you did like 6-8 times lol. I know...I need a life

If I lower the two spokes, the wheel goes out of true, albeit a minor amount. Plucking worked very well. I would say my tones are all really close, and I'm a musician so I trust my ear

I didn't count, but lets just say that I won't be in the running for fastest wheelbuilder on the planet (and I'm fine with that...). Good luck. I don't know what the pros would say, but I'm guessing at some point you just have to take the wheel as-is out on the trails and see what happens. At least now I feel confident that I can take care of any problems that crop up.

Bubba74 · Jan 8, 2008

TurnerConvert said:
...but I'm guessing at some point you just have to take the wheel as-is out on the trails and see what happens. At least now I feel confident that I can take care of any problems that crop up.

I'm with ya. Sooner or later I'll have to call it good. But, I'm comfortable with the whole process and glad I did it.

Homebrew · Jan 8, 2008

Bubba74 said:
I probably did the same process you did like 6-8 times lol. I know...I need a life

If I lower the two spokes, the wheel goes out of true, albeit a minor amount. Plucking worked very well. I would say my tones are all really close, and I'm a musician so I trust my ear

If the rim is round (which DT is among the best) and tension is otherwise even except for two tight spokes on one side, the opposite side should be a bit slack. You should try to loosen the two and tighten up the opposing side. If that doesn't work, you may have to live with it one way or the other. I would much rather have even tension than it be nanometer true.

roger-m · Jan 8, 2008

Bubba74 said:
My average tension on the drive-side is around 130-135, but I have like 2 spokes that are 150 to retain true. Should I back out ALL the tensions to bring these two spokes down? I'm just concerned that the average tension will be lower than I would like to keep these 2 spokes to acceptable limits.

Try and get a micrometer on those two spokes and measure the diameter, it could be they've been made wrong and even 0.05 will throw a big error on the tensiometer. It could be they are at the same tension as the others but the tensiometer is wrongly saying otherwise.

--
Roger

Spoke tension - is there such a thing as too much?

TurnerConvert

coelhomd

dan0

Circlip

FM

roger-m

Bubba74

TurnerConvert

JMH

bad mechanic

Ratt

bad mechanic

TurnerConvert

Bubba74

TurnerConvert

Bubba74

TurnerConvert

Bubba74

Homebrew

roger-m

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