Spoke Gauge Sizing

This is one for Smickle or Spoked Wheel but anyone can help if they have an answer.

When building a wheel does the gauge of the spoke decrease given the lower the number of spokes in the wheel ie get thicker. Say when building a 21 spoke wheel as opposed to a 32 spoke wheel. Surely there will be a weakness in the 21 spoke wheel as opposed to having 32 spokes if the gauge remains the same. I hope I'm making myself clear.
 

I like Skol

Hold my beer and watch this....
The gauge stays the same but.......

2mm seems to be pretty standard today with butted spokes being thinner in the middle to save weight where they typically seem to be reduced to between 1.5-1.8mm. There are alternatives though, my own particular favourite is the DT Alpine III which is thicker at the hub end where most spokes tend to break. The Alpine spoke is 2.3mm at the hub, 1.8mm in the centre and the 'standard' 2mm at the nipple and is great for heavily loaded touring bikes or abused bikes with disc brakes.
 
The gauge stays the same but.......

2mm seems to be pretty standard today with butted spokes being thinner in the middle to save weight where they typically seem to be reduced to between 1.5-1.8mm. There are alternatives though, my own particular favourite is the DT Alpine III which is thicker at the hub end where most spokes tend to break. The Alpine spoke is 2.3mm at the hub, 1.8mm in the centre and the 'standard' 2mm at the nipple and is great for heavily loaded touring bikes or abused bikes with disc brakes.
Cheers for the reply. Does that mean that by virtue of the smaller number of spokes and yet the gauge remaining the same the wheel will be less robust.
 
Location
Loch side.
Always build with double-butted spokes. These spokes were not designed to save weight but to increase durability. Ultimate spoke strength (different from durability) is not the issue but longevity is. If you go over to the Loose Spoke Won't Tighten thread a few threads down, I explained how this all works.

Strength and durability should be separated clearly here. A spoke is strong enough when if you sit on the bike and bounce up and down a bit, it doesn't brake.
A spoke is durable if it can carry its payload for a great distance without breaking.

Spokes break from fatigue, not tensile weakness. Spokes purposely made thicker at one end were designed for a market where users misunderstand the mode of failure of spokes rather than educate the users. The mode of failure is counter-intuitive. Further, a wheel that has been stress-relieved during the build and has the appropriate number of spokes, has a virtually infinite life as far as the spokes are concerned. Unfortunately none of the bicycle trade schools seem to understand the concept and don't teach it as far as I can see.

To answer your question. Build your wheel with 2.0mm/1.8mm/2.0mm double butted spokes.
 

Smurfy

Naturist Smurf
There are other issues to consider besides spoke gauge or thickness. The spoke should be a good fit in the hub flange hole. If the fit is not correct, the elbow of the spoke will slowly straighten due to the bend initially being in the wrong place, and eventually the spoke may snap. In some cases you may need a spoke washer to get a good fit. Best way is to take the hub to the shop, and see which spokes will fit nicely.
 
This is one for Smickle or Spoked Wheel but anyone can help if they have an answer.

When building a wheel does the gauge of the spoke decrease given the lower the number of spokes in the wheel ie get thicker. Say when building a 21 spoke wheel as opposed to a 32 spoke wheel. Surely there will be a weakness in the 21 spoke wheel as opposed to having 32 spokes if the gauge remains the same. I hope I'm making myself clear.
It seems that some factory wheels are built that way.

No, I'd say build with Double butted spokes and enough of them to have a wheel that is strong enough and durable enough. The rear wheel is under much more stress than the front wheel so in some cases, when somebody is trying to save weight, I use double butted 2.0 - 1.5 - 2.0 for front wheels rather than using less spokes.however, this is not always a good idea, for instance, if you are carrying front panniers or have discs brakes then I use 2.0 - 1.8 - 2.0. What I;m trying to say is that not everything is black and white so I don't stick to one type of spoke for everything, it takes a bit more thinking to obtain the best results. There are different thickness of spokes and I consider all the double butted and even triple butted or bladed spokes when it comes to design a wheel for a particular application, but you also have to take into account, amongst others, the weight of the rider, the power of the rider, the mileage,the rim, the hub ( read a little about bracing angles) which is also important when it comes to consider lateral strength and also avoiding certain rim / hub combinations such shallow rims and hubs with narrow flanges.

All of the above are important considerations that help to build a good wheel BUT none of that will help if your building skills aren't up to the task. A good book can be very helpful, I've read a few and I recommend Roger Musson's book above anything else I've read. After building quite a few wheels I read Jobs Bradt's book and although it's a really good book, for me, Roger Musson was easier to follow when I first started. If I could summarise the building process in three key ideas I''d say "sufficient tension", "stress relieve" and "squalised spoke tension"
 
Location
Loch side.
There are other issues to consider besides spoke gauge or thickness. The spoke should be a good fit in the hub flange hole. If the fit is not correct, the elbow of the spoke will slowly straighten due to the bend initially being in the wrong place, and eventually the spoke may snap. In some cases you may need a spoke washer to get a good fit. Best way is to take the hub to the shop, and see which spokes will fit nicely.
With modern hubs and standardized elbow length in all the brand-name spokes you will not come across a hub that's too thin for the elbow. The only too-thin flange I can think of is a steel hub that's not worth even considering. Spoke washers are a thing of the past. There was an era where DT Swiss went bonkers and produced spokes with too-long elbows but I think those spokes have all worked through the system by now and we needn't fuss about them anymore.

Spokes don't slowly straighten themselves at the bend. A bend that springs back like that simply causes residual stress inside the spoke that can be removed by stress-relieving. Brandt describes this adequately. This phenomena is simply not an issue for a wheelbuilder.

Spokes don't snap. Snap indicates a tensile break. Spokes break in fatigue from stress fractures which can happen at high or low tension.
 
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Location
Loch side.
It seems that some factory wheels are built that way.

Cut cut cut cut " and "squalised spoke tension"
Equalised spoke tension is always quoted but I think it has become ritualized in these forums. Equal spoke tension is a myth. A wheel with equal spoke tension cannot be true and a true wheel cannot have equal spoke tension. The reason is simple: rims are not uniform and the weld and valve hole are two areas where the rim performs completely differently from the rest of the wheel. The valve hole is the weakest area and the weld could be either soft or hard, depending on whether there is a lug in there or pins and how the weld was created and annealed. However, these areas are never the same as the rest of the rim. Further, rims are extruded and extrusions are by nature not homogeneous, again creating tension inequalities if the rim is true.

The old adage that unequal spoke tension will eventually equalize is simply not true. I cannot foresee any mechanism whereby a spoke will alter its tension by itself. I know you didn't claim this but I'm adding it here simply because it has been said so often that it has become part of the mythology of wheelbuilding.
 
Equalised spoke tension is always quoted but I think it has become ritualized in these forums. Equal spoke tension is a myth. A wheel with equal spoke tension cannot be true and a true wheel cannot have equal spoke tension. The reason is simple: rims are not uniform and the weld and valve hole are two areas where the rim performs completely differently from the rest of the wheel. The valve hole is the weakest area and the weld could be either soft or hard, depending on whether there is a lug in there or pins and how the weld was created and annealed. However, these areas are never the same as the rest of the rim. Further, rims are extruded and extrusions are by nature not homogeneous, again creating tension inequalities if the rim is true.

The old adage that unequal spoke tension will eventually equalize is simply not true. I cannot foresee any mechanism whereby a spoke will alter its tension by itself. I know you didn't claim this but I'm adding it here simply because it has been said so often that it has become part of the mythology of wheelbuilding.
Yes, I was using the term in the same way you talk abut the "perfect wheel". Equalised spokes tension or balanced spoke tension are used by Roger Mussom, meaning an homogenous tension, rather than a loose spoke next to one that is over tensioned.

I have to say that I have not heard nor read here or anywhere else "The old adage that unequal spoke tension will eventually equalize"having said that, you are quite right, spokes don't tighten by themselves :smile:
 

Smurfy

Naturist Smurf
With modern hubs and standardized elbow length in all the brand-name spokes you will not come across a hub that's too thin for the elbow. The only too-thin flange I can think of is a steel hub that's not worth even considering. Spoke washers are a thing of the past. There was an era where DT Swiss went bonkers and produced spokes with too-long elbows but I think those spokes have all worked through the system by now and we needn't fuss about them anymore.

Spokes don't slowly straighten themselves at the bend. A bend that springs back like that simply causes residual stress inside the spoke that can be removed by stress-relieving. Brandt describes this adequately. This phenomena is simply not an issue for a wheelbuilder.

Spokes don't snap. Snap indicates a tensile break. Spokes break in fatigue from stress fractures which can happen at high or low tension.
My Alfine hub was built by a professional builder, it has spoke washers because the spokes are a smaller gauge than the holes in the hub (I remembered it wrong earlier).
 
Spoke washers are a thing of the past. There was an era where DT Swiss went bonkers and produced spokes with too-long elbows but I think those spokes have all worked through the system by now and we needn't fuss about them anymore.
Well, I have to disagree. For example, Hope hubs should not be built radially with 24 spokes, too much strain on the flanges, 16 and 20 are OK, but one way used by reputable and experienced wheel builders is to use spoke washers and less tension to protect the flanges. Using a spoke punch helps to sit the head nicely on the flange hole. Also, some builders use washers with Royce hubs. I do use washers for 24 radial lacing but not always, Dura Ace are OK without washers. I haven't had the pleasure to lace a Royce hub :smile:

I feel that these things are sold because there is a market which translates in wheel builders are still using washers. I can't imagine so many builders being wrong. If nobody felt there are times when using a spoke washer makes perfect sense then we would not be able to buy them as easily as we do now.
 

the snail

Veteran
Location
Chippenham
Surely there will be a weakness in the 21 spoke wheel as opposed to having 32 spokes if the gauge remains the same.
A wheel with more spokes will be stronger, generally, that's why wheels designed for heavy loadings tend to have higher spoke counts, e.g. tourers, tandems. Low spoke count wheels can compensate to some extent by having stiffer rims.
... double-butted spokes. These spokes were not designed to save weight but to increase durability.
Of course they are designed to save weight/drag. A double butted spoke isn't any stronger than a plain guage, it just uses a thicker section where it is most stressed, thinner where it's less stressed.
I cannot foresee any mechanism whereby a spoke will alter its tension by itself.
The spoke tensions can't equalise, because the rim has strength, but the tendency is for the tensions to equalise, which is why a poorly tensioned wheel goes out of true. The mechanism is that if a spoke has higher tension, the rim gets pulled over which shortens the spoke, which reduces the tension.
 
Location
Loch side.
My Alfine hub was built by a professional builder, it has spoke washers because the spokes are a smaller gauge than the holes in the hub (I remembered it wrong earlier).
The washers solve no known problem in that case. Most spoke holes are drilled to 2.3mm and most spokes are 2.0mm at the elbow and therefore all "too small" for the hole by that definition. By putting a washer under the spoke head you simply increase the effective flange diameter, which is not necessary with modern hubs such as Alfine. If the washers were fitted to prevent too-small spoke heads from pulling through the hole, very strange spokes were used since heads are all the same size.
 
Location
Loch side.
Well, I have to disagree. For example, Hope hubs should not be built radially with 24 spokes, too much strain on the flanges, 16 and 20 are OK, but one way used by reputable and experienced wheel builders is to use spoke washers and less tension to protect the flanges.
I can see how less tension will protect the flanges but not how a spoke washer can help. Perhaps you can explain how a washer next to a spoke head protects the flange.

Using a spoke punch helps to sit the head nicely on the flange hole.
Stress relieving seats the entire spoke elbow into the hole as well as smear the spoke at the exit point into the flange. A punch will do nothing that's required. The tension on the spoke is borne mostly by the elbow and not the head and I don't see how punching a head against a chamfered spoke hole makes any difference. Perhaps you can illuminate this point? [/QUOTE]

Also, some builders use washers with Royce hubs. I do use washers for 24 radial lacing but not always, Dura Ace are OK without washers. I haven't had the pleasure to lace a Royce hub :smile:/QUOTE] Why? are the flanges so thin that they need artificial thickening?


I feel that these things are sold because there is a market which translates in wheel builders are still using washers. I can't imagine so many builders being wrong. If nobody felt there are times when using a spoke washer makes perfect sense then we would not be able to buy them as easily as we do now.

Lots of things are sold because there is a market for them. It doesn't make it a valid product. Bottled water, dreamcatchers, tarot cards, crystals and rabbit's foot comes to mind. That doesn't mean it works or a case can be made for them. Many wheelbuilders can be wrong because lots of myth and lore about wheels exist and very few wheelbuilders have had the opportunity and will to rationalize habits and practices from first principles.
 

Venod

Eh up
Location
Yorkshire
Of course they are designed to save weight/drag. A double butted spoke isn't any stronger than a plain guage, it just uses a thicker section where it is most stressed, thinner where it's less stressed
Hear is a paragraph lifted from DCR wheels website.

A spoke is subject to three key kinds of force. One is constant, because of the tension it is held under and the weight of the bicycle. Sapim refer to this as carry. The others are inconstant (impact and transmission); when an impact is made upon the wheel so the spoke needs to help absorb these irregularities. The spoke will only do part of this, some will be absorbed by other components; rim, frame, handlebars etc. Some is passed onto the rider. It is when a wheel receives these sudden forces that butted and aero (which are also butted) spokes become important. The dimensions of a butted spoke differ from plain gauge because they are not a continuous thickness throughout. Sapim’s butted spokes use the SCFT-system (Sapim Cold Forging Technology). This allows the spoke to be stretched without causing any damage to its molecular structure and Sapim claim this increases the strength in the central portion by at least 48%. Butted spokes can flex and absorb impacts better than plain gauge because their central butting allows them to stretch. The extra material around the elbow and nipple allow strength to be retained in the areas that commonly fail. Finally the thinner central portion allows the butted spoke to be lighter than the plain gauge.
 
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