ClarkinHawaii

New Mavic Open Pro rims laced to new Ultegra 6800 hubs with 2-1.8-2 spokes.

From what I read from prior posts on this subject, 110 kgf is as high as I should go on the DS. So I meticulously adjust until every DS spoke is right on 110kgf.

With all the DS spokes at a uniform 110 kgf, the NDS spokes range in tension from 13-15 on the Park TM-1. 15 is equivalent to 54kgf, 13 and 14 are so low that the conversion chart doesn't even give a value.

My understanding is that NDS tensions less than 60 kgf will result in spokes loosening and wheel going out of true.

My understanding is that DS tensions greater than 110kgf will result in damage to the rims, or at least a shortened rim life.

My understanding is that using thread lock on the NDS is ill-advised since it plays hell with future adjustments.

My understanding is that 2-1.5-2 spokes on the NDS would really help the situation, but these new wheels came with 2-1.8-2 all around and I am not going to buy any different spokes.

Soooooo . . . according to my "understandings", this is a hopeless situation with no good solution. Yet you pro wheelbuilders deal with this every day.

Given that I am not willing to use thread lock OR buy any new spokes, should I opt for too-high DS tension or too-low NDS tension?

In other words, which is the lesser of the evils? NOTE: If these were my personal wheels, I would opt for the lower tension and then just do touch-up truing if/as needed. But these are not my personal wheels and the owner is not capable of doing touch-up truing and lives far away.

HELP! HELP! HELP! Thank you.

EDIT--I should also mention that these wheels are pre-sale, so I have no idea about the weight, ride characteristics, road conditions, etc. of the potential buyer except that they will probably be heavy or they would not be looking for 32-spoke wheels in the first place.

mconlonx

First, stupid questions -- wheel at this point is dished correctly, yes? Also trued radially? You have de-stressed?

Lower tension on the NDS spokes is the way I'd go.

And I use boiled linseed oil as lube/threadlock at the spoke threads/nipple interfaces.

ClarkinHawaii

Yes, dished, trued and de-stressed.

So if I understand you correctly, the boiled linseed oil lubes during the build and then dries and hardenes into threadlock of a sort? Also, what about the smell?--I have read that it turns rancid and people who display their bikes in the living room object to the smell--or at least their wives do!

Bill Kapaun

I'd raise the DS tension just enough to get 65kgf NDS tension, but not exceed 125ish kgf.
I use linseed oil also. It doesn't set up HARD, so future adjustments are still manageable.
You shouldn't need future adjustments on a well built wheel.

There is a way to fudge a little bit-
IF you can spread the drop outs a bit, adding additional spacers under the NDS locknut will gain you a bit better balance.
About 2% per 1mm.
Removing 1mmfrom the DS will also do the same, but you may be limited by other constraints such as the small cog chewing into the chain stay, RDER travel, chain line moving etc.

mconlonx

In that case, then I'd say you are done with that build, even with the low NDS spoke tensions. I'll be interested to hear the thoughts of other wheel builders...

Yes, lubes and then... I wouldn't quite say hardens, more like gums up. Which is one reason I like it more than threadlocker -- easier to true in the future. Or at least that's my opinion, don't have any cite to call it fact. Raw linseed oil might rancidify, but I've never experienced boiled linseed oil going bad. And I kind of like the smell -- better than most petrochemical products, anyway. Except for Triflow. Mmm, banana oil...

davidad

How many spokes?
When I build a wheel I don't bother checking the NDS spokes. My wheels are 32 and 36 spoke. I go for 100 to 110 on the DS and the same on the front.

deacon mark

Build looks fine as true and even. I would raise the DS to 120 true and dish again and be done. It should take 120 or I would never use the rims again.

Al1943

Open Pros can easily take 120 kgf, and probably more, mine have for 12 years.
Blue Locktite #242 works well and unlike their stronger products it does not "lock" the threads. It gives results similar to spoke prep. With sufficient tension you should not need either but don't be afraid to use it.

Drew Eckhardt 

I ended up at 110kgf tensioning with Jobst Brandt's method of alternately adding tension and stress relieving until that exceeds the rim's elastic limit causing it to go out of true in waves at which point you back off half a turn and re-true.

Drew Eckhardt 

You don't want to do that.

Rims aren't perfectly round. Their joints aren't perfectly square. The ferrule at the joint makes it stiffer than the rest of the wheel. You're not going to end up with a wheel that's round, straight, and has all the drive-side spokes at 110kgf.

Park says +/- 20% is acceptable. I can't disagree even though +/- 5-10% is achievable on a relatively straight rim with a possible exception for the joint, no tension meter needed to get there.

With the wheel properly dished 100-110kgf is enough to keep a wheel like that true.

Get it true. Dish it correctly tightening the non-drive-side spokes.

Along the way and as a final step move tension from tighter spokes to looser spokes to bring them up, with having enough tension in the loosest spokes more important than keeping the others uniform.

On a 32 spoke wheel you have a lot of latitude - given a loose spoke with two tight or normal ones on each side you can tighten it 1.5 turns, loosen its neighbors .5 turns each, and take .25 turns out of the outer spokes. 1.5 = .5 + .5 + .25 + .25. Some inexperienced people don't spread their adjustments out enough so they get a few spokes that are really loose and some really tight.

You can also add tension to the loose spokes, add tension to the opposite drive side spokes, and reduce tension in their neighbors, although with the NDS spokes getting half the turns of the DS spokes that helps less.

If you really need to you can compromise a bit on radial true (you won't notice it due to tire compliance) to get the tension up in slack spots, although brand new Open Pros are round enough that doesn't apply in this case.

.

Keep the drive side at 110kgf average, make the wheel true, dish it right, and bring up the loose NDS spokes.

FBinNY 

The low threshold tension for spokes depends on the gauge. The key to remember is that it isn't the tension per se but the amount of elongation of the tensioned spoke. That has to exceed the maximum rim deflection so the spoke can never be slack enough to loosen.

So, revisit that 60-65kgf minimum in that context, and consider that if that's what's needed for 2mm plain spokes, there's plenty of downside room for lighter spokes. This is why I generally use spokes in the 1.4-1.6mm range thickness (center section) for the left rear flange. This affords me plenty of downside room in the minimum tension and I can comfortably drop to 50kgf or less if necessary. Based on a 2:1 tension ratio which is typically worse that I need, I have no problems building wheels with right side tension in the 90-110kgf range.

In your case, if this has butted spokes that are 1.8mm or smaller (center) I'd leave things as they are. There's nothing to be gained by increasing the dead load stress on the rim (except, maybe, for a heavier rider).

Al1943

I never had waves in the Open Pro with 120 or more off. My tension values are based on the Park conversion chart, and I have no idea how accurate they are.
My suggestion to the OP is to check the dish and spoke tension after inflating the tire and tube to riding pressure. The spoke tension will drop a bit and the rim may move slightly toward the drive side. If so it may be possible to add a little tension to the non-drive side spokes while 're-centering the rim. This is often the case with light weight road rims.

Jiggle

It's threads like these that reinforce my decision to never build open pro rims. There are so many better options.

ClarkinHawaii

Better because . . . ?

FBinNY 

I read this thread a bit differently, not as an indictment of open pro rims, since nothing specific was said against them, but as a general advisory about learning a bunch of semi related facts without understanding how they relate to each other.

It's like looking at a pointelist painting and seeing nothing but dots. You have to step back to and let the dots blend together to see the big picture. There is nothing wrong with this wheel, so nothing to fix or worry about.

If he hasn't done it yet, the OP should simply even out the worst tension outliers, properly set the elbows (should have been done earlier), then stress relieve and call it a wrap.

Drew Eckhardt 

Exactly.

For a given slackness tolerance tension needs are proportional to cross-sectional area.

IOW, a 1.8mm diameter spoke needs 81% of the tension on a 2.0mm spoke.

If 60 kgf is OK at 2mm, 49 kgf is just as good at 1.8mm, 38 kgf at 1.6mm, and 34 kgf at 1.5mm.

FBinNY 

Thanks for doing the math I was too lazy to include.

Jiggle

Because a builder doesn't have to summon graduate level wheel building theory to deal with a silly low max tension spec.

FBinNY 

Until fairly recently, we were able to build very light rims into sound durable wheels, using light spokes at reasonable tensions (sub 100kgf). We also didn't use tension meters, relying on feel and common sense to do good work. That was SOP for hand builders for just about a century.

While some people think of dialing in tensions as involving accuracy comparable to sinking a putt, the reality is that the precision involved is more comparable to driving off the tee.

If you were to take bunch of wheels from the various knowledgeable and experienced builders on this forum, you'd be staggered at the range that "good" encompasses.

Drew Eckhardt 

Right.

A tension meter offers no practical benefit to an individual wheel builder beyond indicating acceptable average tension with spot check on one spoke provided the rest sound close.

That works without experience to know what's right. It's faster than Jobst Brandt's iterative no-experience-required method. It works on deep rims where Jobt's method does not. It works without having a correct wheel for comparison purposes, which might be hard to come by with slack wheels built by machines and LBS mechanics who can't do a good job fast enough to be profitable.

For $50 amortized over a lifetime of wheel building that's worthwhile, although beyond that there's no practical benefit.

It may feel good to be more detail oriented and that's fine.

Hub label opposite valve stem. Check.
All nipples have one pair of flats parallel to the rim walls. Check.
Tire label centered on valve stem. Check.
Tensions +/- 10%. Check.

Or not.

No, make that +/- 5%. Argh! Darn bent spot!

Drew Eckhardt 

You don't need to glue your NDS spokes. Enough tension prevents problems.

Grease is great when you're starting from scratch - it keeps the friction low even a decade later and prevents corrosion. You can also use anti-seize where zinc-based would be the scientifically correct option (corrodes preferentially to aluminum spoke beds and nipples if some how water with road salt gets past the grease).

A drop of 3-in-1 oil in the spoke end of each nipple and inside of each socket works when dealing with a wheel built by some one else unless they assembled it dry with alloy nipples and they've already seized up.

JohnDThompson 

Yes.

I've always liked the smell of linseed oil -- it reminds me of my father and his den where he did oil painting.

The biggest caveat with linseed oil is proper disposal of any rags with oil on them. As it hardens into varnish, the reaction releases heat and can actually lead to spontaneous combustion:

Dan Burkhart 

Tension meters always bring out these discussions about whether they are really necessary or not, and while I agree that anyone with any mechanical sense can build perfectly serviceable and durable wheels without one, I consider mine a valuable tool for my purposes, and have even gone to the extent of building a calibration fixture to ensure accuracy.
I build a branded line of wheels for a bike shop with their own in house bike brand, and my standards dictate that the wheels be built to a repeatable consistency. This enables me to evaluate whether or not I'm using appropriate tensions for given rim, hub combos across various spoke types. If I were not monitoring this, I would never know if a wheel failure was the result of improper tension.
So far, I have zero failure data to evaluate, and If I was building by guessing tensions, the result may be the same, but I have my standards, and I'm sticking to them.

FBinNY 

Actually the debate tends to be more between those who use a meter on every spoke in order ot achieve even tension and those who, like you use them as a quality control device to ensure that wheels are within the intended spec.

BITD I never used or needed a tension meter since the wheels I built were all pretty much alike, and I could trust my fingers. These days, rims and spokes vary so much, that I can't trust my fingers to stay calibrated, so I use the tension meter on the finished wheel as a cross check. Tension evenness is never an issue, because the build technique ensures that uneven tension isn't introduced.

Bill Kapaun

I looked up the specs for the 6800 hub and got this. Seems noticeably "wider" than typical, so does this seem correct?
LFD 43mm
RFD 45mm
CTL 41.5mm
CTR 28.5mm
https://leonard.io/edd/hub/1536-shimano-6800-rear

Using Spokecalc, it shows NDS tension should be 69.1% of DS.

Something doesn't seem right if the above hub dimensions are correct.