The center of the handlebar where the stem fastens for mountain bars must be 25.4mm in outer diameter, for Road bars the standard is 26.0mm except when using a Cinelli stem then 26.4mm is needed as Cinelli has their own standard. Each of these sizes would be too big for grips to fit on, nor would it be comfortable to the hand with a grip made to any of those diameters, so for MTB bars, the bike industry generally uses a 22.2mm outer diameter tubing with the bar center made larger in outer diameter for the stem to grip. Road bars have a grip tube diameter between 23.8mm and 24.2mm. Making the center diameter larger is accomplished in two ways. In one case, the handlebar is mechanically made to bulge in the center, expanding the diameter in that one area of the handlebar. Many of the ways that make the bulge in the bar, introduce weakness in the bulge itself, or at the end of the bulge area. Chiefly this is because expanding the metal to make the bulge makes the metal wall thickness thinner as the expansion occurs. The thinner metal fatigues at the junction between the original wall thickness and the now thinner bulged metal, and under extreme stress cracks or shears. The second way is to fasten an extra thickness of metal around the original 22.2mm outer diameter bar tubing to "build out" the diameter to the needed 25.4mm standard. For MTB bars the 22.2mm or 7/8" original diameter is the standard adopted by nearly everyone as the size grips are to fit onto. The common way to add this thickness is to install a piece of rounded metal on top and on the bottom of the handlebar called shims. In some cases a single piece of tubing is used with a single cut lengthwise that allows this "split" shim to expand and slide into place on the handlebar so the stem will tighten both shim an bar in place. In seeking strength in a bar the straight style is significantly stronger than the bulge style, because the grain of the metal and its thickness remain constant, however there are rather few manufacturers of non-bulge bars left. Shimmed handlebars create a stress ride point just at the edge of the shim due to the vast strength difference at the junction. At the center area on some handlebars is a textured pattern cut into the bar that appears to be tiny diamonds are merely raised and descending ridges running lengthwise on the bulge area. This surface treatment is to give metal a grip and known as "knurling", The bar is said to have a "knurled" bulge. Knurls can also appear as thin straight lines pressed into or etched into the metal. One way to make a shimmed handlebar lighter, is to make it from a butted tube. A butted tube, for handlebar use, has a middle section, held by the stem, that is thicker on the inside center of the tube and becomes substantially thinner (on the inside thickness) away from the center 4 inches. In making each of the ends of thinner metal the overall weight of the bar is reduced. The handlebar, provided that handlebar extensions aren't used, doesn't need to be as strong or as thick at the ends, all the stress born by the handlebar comes where the stem grips it. Another way to reduce the weight of bulged style handlebars is to taper the inner thickness. This tapered wall style of reduction begins with the metal thick at the middle, on the inside of the bar. Away from where the stem clamps onto the bar on the inside, the metal gradually begins to get thinner until it reaches the end of the grip, where it is at it's thinnest. Again this is acceptable because the stress develops where the bar is clamped by the stem. This is the safest way to reduce handlebar weight and is the way used by Ancotec and Easton in their bar manufacturing. Aluminum may generally be the lightest metal in handlebar use (yes, titanium is lighter but uncommon). Aluminum is a decent handlebar material because it flexes and therefore absorbs some of the road shocks, but aluminum snaps under much less stress than say the non-existant steel handlebar. As you notice weights drop, remember that some of the bars resistance to fatigue is disappearing with the weight. Reading our Metals section might be informative to learn about aluminum alloys and their yield strengths. Aluminum handlebars are cosmetically finished either by painting or anodizing them. There are two methods of painting. One way is to "powder coat" or "powder paint", or what is more formally known as "electrostatically powder paint". The process involves the spraying of a glass-like paint in a powder form over the metal to be colored. The metal is held by a hook that is also known as an anode. A high voltage charge is put through the piece with the powdered glass paint, that heats the powder paint and fuses it fairly evenly over the surface of the piece. The powder paint process produces a baked-enamel type finish. It's very hard, difficult to scratch and hardly chips. Powder painting is done in many colors. This style of painting adds a slight amount of weight to the piece. The second method of painting is the more common "wet" painting. This involves spraying liquid paint of some sort, single stage, two stage metallic or activated polymer and allowing it to dry, cure, and harden at air temperature or slightly elevated temperatures. Wet painting on handlebars is rare, except in the case of custom paintint to match a frame. Anodizing as a finish process is discussed in more detail in the Metals section of this book. Simply, the process of anodizing aluminum electrically infuses color to a few thousandths of an inch into the aluminum. The process provides a surface on aluminum that prevents oxidation. Anodizing produces a color that appears to have a silver base to it. Among the colors are Black, Blue, Red, Green, Lavender, Orange, Gold, and Silver. Anodizing adds very little measurable weight to the object. Carbon fiber handlebars are made of graphite mesh which is wrapped around a thin aluminum metal core (to re-inforce the stem clamp area), then covered with epoxy resin. This is then wrapped again in graphite or Kevlar aramid fibers and covered with epoxy resins. The entire rolled piece is sometimes put into a large hot oven-like device known as an "autoclave" to cure and harden. Other carbon fiber makers, like Nuke Proof allow their carbon fiber to air cure and harden. After curing the bar may be painted or left un-painted, occaisionally, a clear smooth plastic coat is poured on top to seal the surface. The composite, carbon fibre, or thermo-plastic bar has the unique property of not passing low amplitude or high frequency vibrations through the bar into the riders hands. Because there is no single material or metal which will conduct the vibration, much of it is dissipated in and among the dis-similar layers.
A "flat bar" is a mountain bike handlebar which, when viewed straight on from the front, appears to be a straight horizontal line. Early mountain bike bars curved up, or sometimes down slightly at the end. Flat bars became popular for competitive riding and now virtually dominate the market. There is a fierce competition of claims being made by "manufacturers", (particularly Ritchey and Bontrager in their packaging and ad materials), each claiming to have reached the highest equilibrium point between material "strength" and material "weight". Some even temper this "scientific" information with another axis of "price". While others just make unsubstantitated claims, Ritchey and Bontrager/Titec specifically use bar graphed charts showing their bars being compared to other unknown "handlebars" which are labeled in the chart, for example, "175 g. Al". The comparison, labeled this way, doesn't reveal who made or marketed the other handlebar (frankly speaking neither of them really manufacture even their own handlebar that they are selling in the graph), so the test can be repeated by someone else. The most important aspect is what are these handlebars made of, their real alloy composition, not a labeled weight. If they are made of the same alloy then we are approaching a fair contest. But the contest is not really fair until the design techniques are the same, and that is where we will really see the superior design using the same material. For instance, would it be fair to compare a soft 3000 series alloy in the form handlebar made thick and heavy knowing that will fail long before a 2000 or 6000 or 7000 series alloy? Their results labeling is so poor, that we don't know whether the test is fair. It has to be believed that each of these companies would want to be able to defend themselves if they were found lacking in a "test", so why are they not saying whose "handlebar" they are victimizing in these un-expressively labeled "results". If a comparison is made with a competitor, they should be named! (Incidentally, since Ritchey nor Bontrager make their own handlebars, there may be some reluctance to name the other handlebar because at some time in the future they may have their handlebar made by the same factory.)
As the Soviet Union crumbled, the world saw both a change from a central government, and a scramble by the previous states, now turned republics, for "hard" currency. Russia being a major refiner of Titanium has suddenly found itself as an inexpensive source for both un-machined and finished goods made of Titanium. Russian originating Titanium has now become a primary raw material in the bicycle industry. But, as political instability continues to hang over each of the new states, (didn't you think, when Yeltsin sent the tanks to evict the legislative building in October '93 that is was the behavior of a "banana republic"?), and inflation exceeds 100% a month, this frantic scramble for hard currency from other countries becomes more desperate. When reading about Titanium in the Metals section of this book, you come to understand the complexity of manufacturing Titanium alloys without introducing impurities. The proper making of Titanium alloy is a careful process that requires both patience and intensity. Shortening the process steps to hasten its conclusion, and increase the general yield, is very tempting, and if you were in need of this foreign "hard" currency, you would find the temptation overwhelming. In the United States, when a delivery of Titanium tubing or billets is made to a plant to re-manufacture it into finished goods, there are certain documents that arrive with the shipment. These are documents that state the exact composition of the Titanium alloy for that particular, and entire, shipment. Boeing, for instance, must know that all the tubing in a delivery had the same origin, and met specific standards, not just one or two lengths. Known as "Certification" documents, these become an important aspect in the delivery, because the history of the metal used make that tubing or billet is presented and certified to have made to certain standards, using certain processes, by certain mills or foundries. Absent a clear set of certification documents, who, where, the exact composition, and standards or tolerances that stock was made to, would be unknown. The Certification documents used to certify deliveries of materials, not finished goods to the United States have a particular appearance and should be unique to each delivery. A story within the Titanium and the Ti finished goods industry has developed around some deliveries of Russian originating Titanium tubing. It seems that multiple deliveries were made, arriving with the same set of Certification documents. Because each Certification is unique, this should never happen. Odder still is that the Certification document set used for these deliveries, were really counterfeit copies of actual documents used to certify a shipment between a United States tubing maker and a US finished goods manufacturer. Incidents like this have thrown into doubt the authenticity of the alloy composition of Russian originating Titanium altogether. One of the ways of getting around this certification issue is to have the finished goods (bicycle parts) made outside of the United States so instead of importing tubing that would likely require Certification, what is being imported is handlebars or brake bridges that wouldn't require Certification. At present finished Ti handlebars are made in both Russia and what is known now as "China", (which has been historically referred to as "Mainland China"). Because there are trade restrictions imposed by some countries in buying and importing goods from "China", (particularly after "Tienemen Square"), the handlebars made in "China" are sold to companies in North America by having the transaction "brokered" through a sales office in Hong Kong. There are no trade restrictions imposed on Hong Kong, so doing business this way permits China to market their goods, made of Russian Titanium to enter the United States whether trade restrictions of a 30% duty are imposed by the Clinton administration or not. This practice isn't restricted to handlebars alone. These remarks are made to inform the consumer because presently there appears to be a deliberate deception in the marketing of these goods. It is just easier to pass off low grade or poorer Ti alloys as the real thing. US made Titanium handlebars carry a greater price tag, in part, because of the certainty and the quality of what you are buying. These remarks aren't intended as a slight to a struggling nation, in fact your author finds it uncomfortable that such disparities in lifestyle and standard of living exist.