chuckybb

I'm building a wheel with Mavic CXP Pro and Campagnolo Victory hub 36h and I've used LEFT Sapim Laser 2.0/1.5/2.0, RIGHT DT Swiss 2.0 (14g). It has trued-up and dished very easily but the tensions are very different. Around 30kgf left side and 90kgf right side. Thought I should see what the folks here think. Whether I should switch to a lighter right side spoke or stick with what I have.

SJX426 

I am a big believer in double butted spokes and would prefer them on the drive side (right?) ILO straight guage.
In any case the tension on the NDS should be more than half of the DS. Varies based on rim.

FBinNY 

The ratio between the left and right side tensions is determined by the hub. It's exactly equal to ratio of the sines of the bracing angles. The beauty is that this is (almost*) exactly equal to the ratio of hub's CTF distances.

So, your numbers are off, and the ratios should be closer to 40:60. I suspect that you're failing to use the correct conversions (specific to the corresponding spoke gauges) for your tension meter.

Leave the wheel alone and check your paperwork.

**the spokes don't go to the centerline, so adjust the numbers to account for the offset of the rim's spoke holes.

wheelreason

Are you using the same length spokes? And I know about the InterWeb, but why different gauge?...

FBinNY 

I don't know what the OP is thinking, but using different gauges is an effective way to compensate for the tension differences in dished wheels. People focus on tension, but fail to recognize that this is secondary to spoke elongation which determines how loads change with deflection. It's elongation which determines minimum tension, which is a primary reason that DS tensions tend to be so high. Using a thinner spoke on the NDS side makes it possible to get the same elongation with lower tension, making it possible to build a reliable wheel without going crazy with DS tension.

mpetry912 

a good concise explanation.

I have used 2cross on the NDS and 3cross on the DS and had very good luck with that arrangement.

/markp

cpach

For what it's worth, you've had me convinced and this has been common practice for me for the last few years. Last nice wheel I built was rear wheel for loaded touring, 2.3/1.5/2.0 NDS 2.3/1.8/2.0 DS for this reason. I also semi regularly build with double butted on the NDS only for wheels where both budget and fatigue life are concerns (my last wheel build-eMTB wheel rebuild).

FBinNY 

Are you saying that you actually changed what you do based on something I said here on BF?

Shocking!!!!

noglider 

I followed your advice a few years ago: I built a rear wheel with lighter spokes on the NDS. This was a few years ago. It went out of true slightly last week. No biggie, and I just found my spoke wrench...

Some of us respect you and your advice, though it might be hard to notice because those who don't are so vocal.

ThermionicScott 

Hopefully it's just a matter of misreading the tensions on the chart by spoke gauge, but I would also suggest making absolutely sure that your rim is centered. I like to flip the wheel around in my truing stand to make sure that I haven't accidentally built it off-center.

zandoval 

I am not a wheel building guy but more of a wheel repair guy so I am taking notes on what ya all are posting. For me using a knockoff ChiCom spoke gauge meter the numbers cannot really be used for an accurate set. I do notice the position of the the indicator more then the number represented by the indicator.

I had a recent conversation with one of my sons when truing up my P6 Ravel bike.

"So how much is the difference between the DS and NDS? "
"Duh! Oh... About 1/2 TO 3/4s of an inch on this gauge."
"Well how much is that? "
I pinged the spokes showing the difference in tone between the two and sides and said, "about that much."
I then demonstrated the difference in tension by squeezing the spokes together on the NDS vs the DS.
I then stated, "I have got a spoke tension meter and a chart that show numbers and conversions for different kinds of hubs and spokes but I dont know how to effectively use those numbers." I then squeezed and pinged the spokes again. I then demonstrated the spokes having about the same tension on the NDS but less then the DS with the meter. I said this one feels and sounds right for this bike. The other bikes have different sounds and feels.

The only take away form my post is that the spoke tension meter and its chart are absolutely fantastic and deserve close attention. But they are not the Holy Grail of wheel tuning.

Of course youse guys know this... HA

As a kid I remember trying to adjust a big two barrel corroborator and the timing on a 1964 Oldsmobile. I had to call my Dad out and with seconds he had it dialed in. Yep... Wheel building and Truing have allot to do with Wheel Tuning...

cpach

Related point — do you think there’s any practical downside to thinner spokes rear ds? Tensile strength is fine on 1.5mm sections well past what you’d sanely need. I mostly use 1.8mm sections DS because it’s cheaper, and also slightly easier to avoid windup.

FBinNY 

First of all, lets clear up a possible misconception. Tensile strength doesn't matter, it's about the yield strength and fatigue limits, both of which are much lower. That said the existence if low spoke wheels proves there'll be enough steel. Also, even with 1.8mm butted spokes failures still only happen at the elbow, so that's what it's really about. I assume that those 1.5 spokes are DB 1.8/1.5, so the 1.8mm elbow is what you're concerned about.

Some perspective. Back in the Bronze age, no serious builder ever used anything heavier that 15g spokes for performance wheels. 14g was relegated to "truck" wheels, aka the general purpose wheels on general purpose bikes. Quality hubs were drilled 2.0mm so 14g spokes wouldn't fit unless you forced the threads through. Keep in mind that that was with 36 spokes, but I'll still be fine with 32. I started using 14gDB spokes mainly for loaded touring and tandems, including one tandem that went NYC to LA and back without issues, so yes, there's plenty enough steel in 1.5mm spokes for a solo rider of reasonable weight.

Ignoring the problem of twist which is no joke on the tight side, the bigger issue is the fit of the elbows in the larger holes of modern hubs. Poor support at the elbow is the major cause of failure, so you'll have to be super diligent about setting the elbows to minimize movement there. Concern about the elbows is one reason I stay with 14g for most rear wheels. So, I limit myself to working with the lightest 14g spokes I can source.

Building for yourself, no reason not to go light, but warrants more thought if building for someone else where anger over a broken spoke may overshadow the appreciation of the weight savings.

FBinNY 

We've been building wheels without using a tension meter for over a century, so obviously they're not critical. Until fairly recently (on my time scale) spoke tension meters were ONLY used for QC in bike factories. The first time I ever saw a reference to using a tension meter for a build came from John Barnett who I credit (blame) with inventing the tension chart method. I now will sometimes use a meter to double check my fingers, but ONLY as a reality check on the finished wheel. But I'm old skill and trained to focus on process to produce consistent result.

Bill Kapaun

They are a 2.0-1.5-2.0
https://www.dtswiss.com/en/component.../dt-revolution

Personally, I think 1.6 is too light on a DS rear unless you ride "petitely".
No personal experience, but I think I've read that a 1.5mm is on the verge of deformation at DS tensions. You reach a point that you turn the nipple and nothing happens except you run out of threads and have a slightly longer spoke?

FBinNY 

This may be a case of "if you can't raise the bridge, lower the water".

Yes, it may be possible to take 1.5mm (or any) spokes beyond yield, (which is why I mentioned that), it doesn't necessarily imply that you need a heavier spoke. It might equally imply that you need to limit tension accordingly.

Thinner spokes have both lower maximum and minimum tensions. So it should be possible to build a dished wheel with both sides within proper limits.

Though a long time proponent of mixed gauges for dished wheels, I don't consider it a requirement.

cpach

Makes sense. I pretty exclusively use spokes with either 2.0 or 2.13mm elbows and 2.0 threads for those reasons.

I don't really end up prioritizing weight often anyways, though my personal road wheels are frequently lighter than I'd build for a customer of my (presently heavy) weight and I've never had a spoke failure for a wheel I've built myself.