Keefusb

A couple of winters ago, I decided to break the monotony of COVID lockdowns by building my first wheel set in many years. I was looking for a super strong wheel and didn't care so much about pinching grams in the building process. I used 36 hole DT Swiss rims (TK 540), Shimano Ultegra/600 Tri-color hubs, and Sapim Laser double-butted spokes laced 3x with brass nipples. I have been regularly riding these wheels for about a year now with no issues, no truing needed, etc.

I am going to re-build an older wheel set that I have. I will be using Mavic Open Pro SUP CD Ceramic rims (32 hole in front, 36 hole in rear laced 3x) that are currently laced to RX100 hubs (that are close to end of life due to cup pitting). I will be using Shimano Ultegra/600 Tri-color hubs (NOS) and some flavor of double-butted spokes. I will also be using standard brass nipples.

The Sapim Laser spokes I used on my last wheel build are butted 2.0-1.5-2.0, and seem to be strong and sturdy spokes. The wheel that I am re-building currently has 14g straight gauge spokes.

From purely a strength standpoint, am I better off using a 2.0-1.5-2.0 double butted spoke, or would a 2.0-1.8-2.0 be stronger?

Like I mentioned previously, I'm not concerned so much about weight. More concerned about strength and not needing to true wheels frequently (I weigh about 215# at the moment). I understand that the butting/swaging process gives butted spokes more strength, but I wasn't sure if that process yields some sort of diminishing strength return once the diameter of the butted section gets to or is below 1.5 in a 2.0-1.5-2.0 spoke.

Looking for some opinions or data about which spokes would be stronger.

cyccommute 

Here’s data. In the graph and in the double butted category, the 2.0/1.5/2.0mm spokes are the weakest of the double butted spokes.

Andrew R Stewart 

As spokes rarely break at their mid sections the strength of that portion is rarely an issue. The vast majority of spoke failures are at the ends, the elbow or the threading. Far more common is the wind up issues of really thin spokes that fights the tensioning up process.

Now if by "strength" you actually mean a wheel that won't break spokes as readily as another might than butted spokes will be better. They have a bit more elasticity/stretch and thus won't as willingly go slack/untensioned during the riding. Using unbutted spokes is all about cost savings and not wheel longevity. Andy (who uses 2.0/1.8 spokes for nearly all his wheels and all with brass nips)

79pmooney

If the rear wheel is a highly dished for example, 8, 9, 10 ... speed, more important than exactly what gauge you run if having the right rear spokes heavier than the rest. I love the 2.0 (or 1.8; I don't pop spoke heads but I weigh 150) - 1.5s but put 2.0-1.8s on the right rear. (If I were you, I'd go no lighter than 1.6 just to have a stiffer wheel but if it works for you, go for it.) I use the same spokes for the front and left rear.

Highly dished rear wheels have such unequal spoke tensions that going to very different gauges allows each side to work at its best tension, midway between going loose as your weight compress the wheel and so tight that spokes break, nipples have issues, etc.

Keefusb

I see that...data is a good thing! So the inference is that the 2.0-1.8-2.0 double-butted spokes would be stronger than the 2.0-1.5-2.0. The cost difference is minimal, so that's also a good thing!

Keefusb

The rear wheel will have a 9-speed 11-30T cassette, so there will definitely be some tension differences on the DS vs NDS. My plan was to go with 2.0-1.8-2.0 all the way around.

Bill Kapaun

On the rear DS, 1.5mm spokes are near their elastic limit. I won't go less than 1.8mm, typically a 14/15/14.
I typically use 1 gauge heavier on the rear DS than the rear NDS & front.

CliffordK

What is your ultimate application?

You can also purchase 2.3/2.0 spokes. Probably not necessary for a lot of ordinary road riding, but it might be good for a cargo application.

At some point Shimano started using taller flanges on their hubs. I think the Shimano 600 had the short flanges, and the Ultegra 6500 had the taller flanges.

There is a rare hub breakage that seems to be related to lacing a 36h front wheel radial.

But, I might choose the Ultegra 6500 over the Shimano 600.

For higher spoke counts, I also like some of the mid or high flange solid flange hubs. I think some of the Deore hubs fall in that category, but unfortunately they are rarely with 36h.

FBinNY 

Thinking purely about strength can be misleading. Thinking of spokes as components within a system, and how the system works is more inciteful.

Ideally you want spoke tension such that spokes are stretched enough to remain under tension at all times, and still have upside room for added loads without reaching yield limits. As a rough guideline roughly 80-90% of yield will be ideal.

Now, consider that dish mandates different tensions with the left side being, for example, 60% of the right.

That would imply that for both sides to be near ideal tension, the cross section of left side spokes should be 60% of those on the right.

So, consider mixed gauges, ie. 1.8R & 1.5L. Since you have to buy 2 lengths anyway, buying 2 different spokes isn't an issue.

Keefusb

So as far as applications go, these wheels are strictly my back-up wheel set in case of failure of one of my wheels that is currently installed on a bike.
I don't race anymore, so I won't need to drag them to events where I made my wife the keeper of the spare wheels. I recall needing them one time when I flatted in a criterium and happened to be about 100 feet from where she was standing with my spare wheels.
This wheel build is primarily to replace the old and scratchy/lumpy RX100 hubs that have seen their share of foul weather riding over the years. The last time I serviced the hubs, I could see and feel some significant pitting in the cups. Cones looked OK. The Mavic Open Pro rims are in excellent shape, rim sidewalls are good, and no detectable cracks around the eyelets. I figured that I would replace the 25 year old straight gauge Wheelsmith spokes while I was at it, and give myself some additional wheel building experience.
The bikes that will likely have these wheels installed in the event of a problem or an emergency would be my 1989 Eddy Merckx Corsa Extra, or my 1992 Paramount Tange Prestige. Good old-fashioned lugged steel bikes where I'm not super concerned about weight. Durability and reliability are my chief concerns.

maddog34

2.3 mm spokes will typically require a re-drilling/re-chamfering of the hubs to fit...
I just built a pair of 36 hole 29er wheels with Deore XT Disc hubs... Ebay came thru once again.;-)

Lombard

I think this is a better choice than 2.0-1.5-2.0. The wheel won't be any stronger per se, but 2.0-1.5-2.0 spokes are a bear to work with as there is a lot of spoke twist while building. In general, butted spokes have better longevity than straight spokes. It may seem counter intuitive, but when you factor that the weakest part of the spoke is at the nipple and the j-bend, a spoke with a thinner middle will flex there and be less likely to fatigue at the ends.

To be clear, wheel strength is determined more by spoke count than anything else. Although I have a feeling when you say wheel strength, you are referring to longevity rather than stiffness.

BTW, as long as you are going to this trouble, I would pitch those Mavic Open Pros. If you do plan on keeping them, check the spoke holes carefully with a magnifying glass for spoke hole cracks. They are known for that. There are clearly better choices. Not to mention that these rims are only designed to tolerate a max 90kgF. Most quality rims can easily take 130kgF which will give you a more than adequate 70kgF on the NDS of an 8-9-10 speed freehub.

Dan Burkhart 

Not true of most modern hubs. 2.3mm fit just fine.
Might be a bit too tight for some vintage road hubs.

cyccommute 

Not in my experience. The only hubs I’ve had problems with fitting 2.3mm spokes was an old Ringle’ hub. Even that needed only a little bit of drilling and no need to chamfer the hub. Most all modern hubs (around 2000 on) are 2.6mm to fit the 2.3mm rolled spokes. I’ve used 2.3mm spokes on hubs from Shimano to Phil Wood to most of White Industries catalog. Never had a problem.

Koyote

I once had a wheelset built with 2.0/1.5 DB spokes. DT Revolutions. 32h 3x. Rear DS spokes wound up too much in the building, and stress relieving did not sufficiently address it -- they would unwind while riding, usually before I got to the end of my driveway, and wheel would go out-of-true. I had the wheels rebuilt with 2.0/1.8 DB spokes and they're still in good shape about 15 years later.

cyccommute 

That’s only partially true. This article by Ric Hjertberg (founder of Wheelsmith) explains why stronger spokes, i.e. 2.3mm heads, make for stronger, more durable wheels. He states that going to spokes with 2.3mm heads is like adding 10 spokes to the wheel. I wouldn’t go that far but it is, at least, the equivalent of adding 4 spokes. In other words, a 32 spoke wheel with 2.3mm spoke heads performs like at least a 36 spoke wheel and a 36 spoke wheel with the same spokes performs like a 40 spoke wheel. They are amazingly robust!

Lombard

Stronger by what definition? Less likely to break at the j-bend - definitely. But the load on the rim by each spoke is the same regardless of spoke head size given a constant spoke count.

Also, strength has its diminishing returns. While I think the low spoke counts on many factory wheels these days are truly ridiculous, 32 spokes is plenty for a rear wheel for most road riders under 200 lbs. The front can be less on a rim brake bike because there are no twisting forces like there are for the rear wheel due to the drivetrain. Now a mountain or a loaded touring bike is a different story.

cyccommute 

Stronger by the only definition that counts…less likely to break at the j-bend. Load at the rim makes little difference to wheel “strength”. The rim makes little difference to the wheel strength overall. With the exception of wheel collapse…which is related to spoke failure more than rim failure…there are many modes of rim failure where the rim can simply be replaced. The wheel can continue to be reused after a rim replacement.

Broken spokes, on the other hand, make the wheel very suspect and continued spoke breakage will eventually result in the wheel failure. Yes, you can replace the spokes but the wheel is likely to continue to need spoke replacement until all the spokes are replaced.

As you point out, there is a different story. A light rider will seldom test the strength of a 2.0mm spoke of any kind. There are other applications where a much stronger wheel is needed. Not all riders are under 200 lbs, either. Just because spoke failure isn’t a problem for some doesn’t lead to the conclusion that it isn’t a problem for all. Alternatively, adding about 7g per wheel…the weight “penalty” for 2.3mm headed spokes in a 32 or 36 spoke wheel…is a small weight investment for a relatively large improvement in spoke strength.

Lombard

Well IDK, spokes are much cheaper than rims. And I question that the rim makes little difference. Poorly designed rims that get spoke hole cracks can cause a wheel to collapse as well as if enough spokes break at once at the j-bends. Most spokes break due to a poorly built wheel rather than any flaw in the spokes themselves.

Keefusb

No visible cracks around spoke hole eyelets. Rims are in good shape, no point to pitching them.

cyccommute 

While rims can crack, seldom do they fail catastrophically. Wheel collapse isn’t much of an issue. Even single walled rims can last for a very long time without issue.

A broken spoke is a catastrophic failure by definition. They don’t crack and bend, they fracture usually at the head where they are stressed the most. And spoke failure is a constant problem.

I disagree. A poor build can make spokes break but spoke breakage isn’t always due to poor builds. I’ve broken a lot of spokes on well built, evenly tensioned wheels using double butted spokes. Once I switched to using triple butted spokes (about 20 years ago), spoke breakage dropped to zero. I know how to build and I haven’t changed the way I build from 20 years ago. Wheels are still tensioned as tightly and evenly as I used to build them. The only thing that has changed is the gauge of the spoke head. Even Hjertberg, who, again, founded Wheelsmith, knows that spokes breaking is a possibility and a problem. The “flaw” is the spokes themselves. They are too light for the job

Lombard

I wasn't paying attention in your OP when you stated your Mavic Open Pro rear wheel is 36 hole. Unless you are very heavy, you should be fine.

Lombard

A catastrophic failure? Have you ever heard of anybody crashing because of a spoke break? A ride ender, maybe, and even then an adjustment can often be made in order to get home unless the spoke count is less than 24. But catastrophic? Not unless enough spokes break at once to make the wheel collapse.

Note that I said MOST not ALWAYS.

Good grief Charlie Brown! If you are breaking lots of spokes, you are either doing something wrong in your build or you are 250lbs +. When you say you have broken lots of spokes, how many miles do you have on these wheels when spokes start breaking?

What can I say? You found a solution to your spoke breakage. But something still doesn't sound right.

Keefusb

I suppose I'm heavy by cycling standards (215#), but I see a lot of people riding expensive carbon road bikes who are clearly heavier than I am. I had to sell my Mavic Heliums because I was just too heavy for them. Nowadays I'm much more interested in durability of the wheels I buy and build. I think the Mavic Open Pro rims with the Shimano tri-color hubs and 2.0-1.8-2.0 spokes should make for a set of sturdy long-lasting spare wheels.

cyccommute 

The definition of catastrophic failure is “is a sudden and total failure from which recovery is impossible.” Catastrophic failure may lead to a cascade of failure but not always. Rims seldom fail in that manner. Their failure is one from which recovery is impossible but it is not usually sudden nor total. A cracking rims, for example, is a slower failure. They creak and make noise but seldom collapse. Spokes, on the other hand, go ping! and are broken.


I would say that FEW broken spokes are due to poor builds. Most heavy riders and/or heavy riders carrying heavy loads are going to experience broken spokes.

Frankly, it’s none of your damned business how much I weigh. Let’s just say that I am a large rider who rides aggressively. I don’t track how many miles I have on wheels before they broke spokes but the spokes I used…good quality double butted ones…were not up to the job.

It doesn’t sound right because using light spokes in a build for a large, aggressive rider isn’t a recipe for the “right” spokes. If you weigh 120 lbs soaking wet, you will aren’t likely to ever experience spoke problems. But not everyone weighs 120 lbs and spoke breakage is a problem for lots of those people. On the other hand, the weight penalty for triple butted spokes is small and for those who do weigh 120 lbs soaking wet, they will have the ultimate in bombproof wheels.