General Cycling Discussion - Spokes?
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02-26-03, 07:22 AM
I'm confused about some of the spoke terminology. Butted, double-butted. Guage numbers, what do they mean? What about guage numbers with a slash, such as 14/15? Alloy nipples and brass nipples. Stainless steel spokes, titanium spokes...any advantage there? Anodized spokes...does that have to do with only the color of the spoke, or is there some additional reason? Thanks.
Butted: one end is of a greater diameter than the other
Double butted: the center is of a thinner diameter
Gauge: Lower #, larger diameter
Gauge # with slash: Double butted, different gauges
Alloy nipples: avoid these
Stainless Steel spokes: general good-quality spokes
Titanium spokes: expensive
Anodized spokes: spokes that have been anodized.
02-26-03, 08:04 AM
Whats wrong with alloy nipples? Sure, on your disc brake rig you might want brass... but I was under the impression that on the road with a good quality spoke and a strong rim alloy was fine and even saved you 50 or so grams on your wheelset.
Originally posted by RareVos
Whats wrong with alloy nipples?......and even saved you 50 or so grams on your wheelset.
Brass distorts less.
Disimilar metals cause corrosion. An alloy rim with stainless inserts with alloy nipples with stainless spokes and an alloy hub? Do the math. When you clean the bike, look closely where these items touch each other.
If you race and every ounce matters and you own your own wheelbuilder then it may not be an issue.
Personally, I like to be able to true a wheel years down the road and not expect the spoke and nipple to have become one.
Disimilar metals cause corrosion.
Except when one of the metals is non-reactive. The top grade of stainless steel is non-reactive.
Brass is fairly low on the reactivity spectrum, and the chrome plating on brass nipples lowers the reactivity even more. Also, brass is more malleable, and is less likely to break-although it is more likely to round...
P. B. Walker
02-26-03, 04:12 PM
Plus triple butted where one end is thicker than both the center and the other end. The smaller end is thicker still than the center. Usually referred to by 3 numbers separated by slashes. 14/16/15.
02-28-03, 09:25 PM
I used to be triple butted but now I'm just double butted. With a bit more cycling I should end up being single butted.
Oh! You're talking about spokes. Sorry.
02-28-03, 10:49 PM
I'd be happy to go from 12 gauge to 15 gauge.
Nipples and spokes explained, by Sheldon Brown;
The material of choice for spokes is stainless steel. Stainless is strong and will not rust. Cheap wheels are built with chrome-plated ("UCP")or zinc-plated ("galvanized") carbon-steel spokes, which are not as strong, and are prone to rust.
The leading brands of spokes available in the U.S. market are DT and Wheelsmith.
Titanium is also used for spokes, but, in my opinion it is a waste of money. Titanium spokes should only be used with brass nipples, which makes a combination that is not significantly lighter than stainless spokes with aluminum nipples.
Carbon fibre spokes have been available, but turned out to be brittle and dangerous.
The diameter of spokes is sometimes expressed in terms of wire gauges. There are several different national systems of gauge sizes, and this has been a great cause of confusion. A particular problem is that French gauge numbers are smaller for thinner wires, while the U.S./British gauge numbers get larger for thinner wires. The crossover point is right in the popular range of sizes used for bicycle spokes:
U.S./British 14 gauge is the same as French 13 gauge
U.S./British 13 gauge is the same as French 15 gauge
Newer I.S.O. practice is to ignore gauge numbers, and refer to spokes by their diameter in millimeters:
U.S./British 13 gauge is 2.3 mm
U.S./British 14 gauge is 2.0 mm
U.S./British 15 gauge is 1.8 mm
U.S./British 16 gauge is 1.6 mm
Spokes come in straight-gauge or swaged (butted) styles. Straight gauge spokes have the same thickness all along their length from the threads to the heads.
Swaged spokes come in 5 varieties:
Single-butted spokes are thicker than normal at the hub end, then taper to a thinner section all the way to the threads. Single-butted spokes are not common, but are occasionally seen in heavy-duty applications where a thicker than normal spoke is intended to be used with a rim that has normal-sized holes.
Double-buttedspokes are thicker at the ends than in the middle. The most popular diameters are 2.0/1.8/2.0mm (also known as 14/15 gauge) and 1.8/1.6/1.8 (15/16 gauge).
Double-butted spokes do more than save weight. The thick ends make them as strong in the highly-stressed areas as straight-gauge spokes of the same thickness, but the thinner middle sections make the spokes effectively more elastic. This allows them to stretch (temporarily) more than thicker spokes.
As a result, when the wheel is subjected to sharp localized stresses, the most heavily stressed spokes can elongate enough to shift some of the stress to adjoining spokes. This is particularly desirable when the limiting factor is how much stress the rim can withstand without cracking around the spoke hole.
Triple-butted spokes, such as the DT Alpine III, are the best choice when durability and reliability is the primary aim, as with tandems and bicycles for loaded touring. They share the advantages of single-butted and double-butted spokes. The DT Alpine III, for instance, is 2.34mm (13 gauge) at the head, 1.8mm (15 gauge) in the middle, and 2.0mm (14 gauge) at the threaded end.
Single- and triple-butted spokes solve one of the great problems of wheel design: Since spokes use rolled, not cut threads, the outside diameter of the threads is larger than the base diameter of the spoke wire. Since the holes in the hub flanges must be large enough to fit the threads through, the holes, in turn are larger than the wire requires. This is undesirable, because a tight match between the spoke diameter at the elbow and the diameter of the flange hole is crucial to resisting fatigue-related breakage.
Since single- and triple-butted spokes are thicker at the head end than at the thread end, they may be used with hubs that have holes just large enough to pass the thick wire at the head end.
Æro (elliptical) spokes are a variety of double-butted spoke in which the thin part is swaged into an elliptical cross section, which makes them a bit more ærodynamic than round-section spokes. The most widely available spoke of this type is the Wheelsmith Æro. These are 1.8mm (15 gauge) at the ends, and the middles are equivalent to 16 gauge, but in the form of a 2.0 x 1.6mm ellipse. The Wheelsmith &Aelig;ro is my favorite spoke for high-performance applications, not just because of whatever ærodynamic advantage it may offer, but because the flat center section provides an excellent visual indicator to help the wheelbuilder eliminate any residual twist in the spoke. This helps build a wheel that will stay true.
Æro (bladed) spokes have a more pronounced æro shape, flat, rather than elliptical. Although they are the most ærodynamic of spokes, they won't normally fit through the holes in a standard hub because they are too wide. To use "blades", the hub must be slotted with a file. This can weaken the flange, and will usually void the warranty of the hub. It is also a lot of trouble.
There was a fad in the early '90s for Hoshi "blades" which had a double bend instead of a conventional head. This allowed the spokes to be inserted "head first" into the hub flange, so that they could be used with normal hubs. Unfortunately, they turned out to be prone to breakage, and I can't recommend them.
My Bicycle Glossary has a Table of Spoke Weights, for those who care about such things.
Nipples are commonly made of nickel-plated brass. This is a good material choice, because brass takes very smooth threads, and brass nipples don't get corroded into position too easily.
For light-weight, high-performance wheels, aluminum nipples are available. Aluminum nipples do save a small amount of weight, and they can be quite reliable if used properly. They should only be used with rims that have eyelets of some material other than aluminum, because aluminum/aluminum contact between rim and nipple can result in chemical welding, immobilizing the nipples.
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