The place of grips is special, you want them to absorb the majority of shocks that would transfer to the hands while you want to feel how the bike and road respond to each other. What we are looking for is firm softness.
Grips are made of several materials. They include, hard thermoplastic,soft thermoplastic, several types of rubber compounds, and lofted rubber foam grips. For some applications multiple layers of cotton or padded vinyl tape are used.
Hard plastic grips are sold at "dime" (department) stores and merely provide a defined area on the handlebar for the hand to rest. They do not absorb shock and they do not transfer a "feel" of the nuances in the road. Some grip makers use a soft plastic (AME Mountain Grips) that transfers feel and eliminates shock. Plastic is more difficult to tear and rip when you fall and the bar ends try to break through the grip end. In the truest sense all of the "rubber" used for grips is really plastic. Rubber is a term that is used fast and loose in the bike industry Rubber as a product at first was only available as a refined material using the sap from a rubber tree. Multiple cuts are made on the trunk of a rubber tree and the sap (a white liquid substance) that weeps from the tree is collected in small dishes and dried slightly, then "spun" onto a ball for transport to a manufacturing plant. At this point, with a slight bit more refining we will have "Latex" rubber. Latex rubber is only derived from Rubber trees. Latex rubber because it's labor intensive is very expensive and exists in bicycles only as tubes for tires. Latex rubber is too soft and supple to be exposed to real abuse.
Finished latex rubber is butter-yellow in color. If you were to add sulphur and carbon (as a filler) to latex rubber and heat slowly for a period of time, the latex becomes harder, more firm, and more resistant to abuse. This is the process that brought society the first automobile tires. During World War II a rubber shortage focussed the world to find a substitute rubber compound. The chemical industry brought forth a petroleum based "rubber like" compound that has become known as butyl rubber. This is what is used in many forms and colors for almost all of the "rubber" products today. There are no Latex rubber grips, only different forms of synthetic rubber ones. But they do have natural rubber-like feel and they are affordable.
The type of rubber most used in bicycle grips is referred to as "Kraton" rubber by most of the manufacturers that use it. Kraton is a trademarked name owned by the Shell Oil Company but is a title used by many to a chemical composition of butyl rubber. This style of rubber has a genuine suppleness that brings with it, probably the most ideal version of "firm-softness". Your sense of "control" seems obvious, using this type of grip. Beyond that, it has a remarkable hand-adhesion quality or what is called "tackiness". When you first put grips made of this composition hell Oil Company calls "Kraton"on a bike, the un-gloved hand seems to "stick" to the grip. When you remove your hand you find that it's clean of any sticky material, though you would swear had to wash something stick from them before. The style of rubber reacts with palm oils to become even more adhesive. It's truly a remarkable compound. (If you get the impression that we are using this "K" type name cautiously because the Shell attorneys are having kittens because we are explaining this ...... you are right. Buying Shell gasoline is perpetuating their crusade of trademark protection in the electronic press. Even though we explain it to be a trademarked name and by whom, we get phone calls and letters for having used the name in the grips explanation.)
Foam grips are made using closed-celled foam. Closed-cell foam, encloses a bubble of air in each foam hole, that must be compressed under pressure. It is these closed "atmospheres" that give foam grips their body and cushion. All foam grips, with exposure to the air, over a period of time will develop a "skin" on their outside surface. The surface will loose it's soft rubber, tacky feel. This "skin" can be removed by using a cloth and rubbing lacquer thinner around the exterior of the foam. It will not destroy the grip, it just removes the exterior, and makes it feel like new.
To measure the hardness of the rubber compounds used to make the grips, an instrument called a "Durometer" is used. This way we can present you with objective information about how soft one grip is to another. The harder the grips rubber the resistant it will be to abrasion and tearing. The Durometer is the rubber industries tool for hardness measurement. Our Durometer is the Pacific Transducer Corporation's 408L. It is certified to meet or exceed the current ASTM D2240 specifications for "A" type durometric measurements in the 10/A to 90/A range. The hardness test on rubber reflects such qualities as resilience, durability, uniformity, tensile strength, and abrasion resistance. A 10/A reading is very soft and a 90/A reading is very hard.
The Durometer uses a highly accurate spring to measure how deep a blunted needle can penetrate into the rubber or polymer substance. The amount of pressure is measured as "load grams". The lowest 10/A reading requires 130 load grams, while a 45/A requires 400 load grams and the highest for our instrument 90/A requires 746 load grams. As the reading gets higher the amount of added force or pressure decreases relative to the increase in the instrument reading. The results we print of this test are the average of 5 objectively performed, separate tests in a controlled temperature environment.
Though the durometric hardness testing was performed accurately, we've discovered that the color of the rubber material seems to affect the finished hardness of the grip. For example, we know that ODI makes their own grips, the grips sold as "Answer" grips, and the WTB Trailmaster grips. The rubber to make (mold) the grips for all of these, will come in many cases from the same rubber lot though different molds, or "inserts" will be used to make the particular grip. The rubber comes to the grip maker in the forms of "pellets". These pellets are round, slightly larger than a "BB" at about 17/100ths of an inch in diameter. The pellets come in Black, Clear, or Milky White, latex-type color. Pellets come in packaged in 1000 pound quantities referred to as "gaylords". Once at the injection molding site the pellets are heated to a temperature that makes the rubber material "plastic" meaning that it's not hard with substance nor burning from overheat. The rubber in the plastic state is then injected into the mold area or "cavity" which contains several "inserts". Inserts are the mold which forms the exterior of the grip, a separate piece known as the "core" fits within the insert to make the cylindrical hollow that will be filled by the handlebar when the grip is installed. The mold cavity will hold several inserts, in even, paired numbers, either 4, 6 or 8, and is referred to as a "4 insert cavity" or "6 insert cavity" or "8 insert cavity". When multiple inserts are used in one cavity, the inserts are said to be "ganged". It is also possible to fill unused insert positions in the cavity with blanks, if a short run of grips in an uncommon color were needed. Using multiple inserts in one injection process increases the efficiency of the machine time.
Another method of increasing the efficiency is to make grips that are thinner, (have thinner walls). The period of time it takes to fill the insert around the core is known as "fill rate". Grips that are thick have a greater area that the heated rubber must fill within the insert/mold. It takes more time for rubber to completely migrate and fill the larger area. More time spent filling the insert means less grips are made per hour. As a purely practical matter thin walled grips should sell for slightly less, but the market place doesn't acknowledge this savings, and in some cases thin grips because they are thought to be fashionable cost more. To make the various grip colors, the Clear or latex-white pellets are mixed with colorant pellets. The hardness of the finished colored rubber is the product of blending un-colored rubber pellets of two hardnesses to produce a medium hardness version, and the addition of colorant pellets. Blending an A/30 and A/44 pellets, in the proper quantity, should yield a medium 30s rubber compound. The colorant material is added in a certain quantity, generally in the region of 1 colorant to 4 un-colored. When heated and mixed the master colorant pellets blend to create the colored grip rubber. Specific amounts of each type of pellet are used to make the colors we all recognize. The pellets for grip manufacture commonly come from a few sources, two well known ones are J-Von and G.L.S. "Kraton" used as a brand name for rubber was a trade name brought into the market place by G.L.S. which was recognized a sell through subsidiary of the Shell Oil company, which was once or may still be a part of Royal Dutch Shell. Shell provided the formulation for the compound that has become known as the Shell trademarked "Kraton", and intended G.L.S. as its subsidiary to be its sole outlet for the Kraton formulation.
Sometime later J-Von found its way into selling the pretty much the same rubber compound but couldn't use the name Shell trademarked "Kraton" name. "K" type rubber is now available world-wide form several sources and not necessarily just from Shell. The colorant pellets are made and colored using different compounds that yield the desired tint. The compounds that make the color also seem to affect the texture and hardness of the finished grip. How much and of what type modifies the basic durometer hardness of the un-colored pellets, though there are other factors such as temperature of the manufacturing environment, age of the un-colored pellets and time required to cool the molded rubber to room temperature. We tested the hardness the hardness of the rubber from a few pair of grips pulled randomly from our inventories to discover how the coloring may have affected the hardness. We found Red grips had a hardness of A/33, while Blue was A/36, Lavender was A/47, and Turquoise was A/35. Clear tested at A/42 and Black though we had believed it would be softer tested to a hardness of A/51 on Both the Yeti grip and the WTB grip.
For road racing and mountain bike handlebar extensions, people are now using "Ribbon" or "Tape" (sometimes called "padded tape"). For many years when cycling gloves weren't used or they didn't pad the palms well enough, people would wrap multiple layers of self-adhesive cotton cloth handlebar tape around their handlebar to build up and create a padding. Italian vinyl handlebar tape used to come as a thin vinyl strip that merely gave you a plastic surface rather than gripping the metal bar. The Italian makers noticing the trend to cloth wrap, and began to make vinyl tape with a thick foam style core to pad the tape and thereby the handlebar. Besides using a foam core padding in the tape, one maker, Cinelli, uses a cork base in it's tape to develop the padding. Cork is more expensive, but people who have used both swear by cork as the better of the two.
We use liquid soap (dishwashing liquid) or hairspray (anything cheap) to install grips. Liquid soap almost everyone has on hand. You smear it on the bar and in the grip and the grip should slide right on. The soap and water will dry out of the grip in a few days. We use hairspray more commonly here at the store, (especially if it's a slightly loose fit), because hairsprays are generally lacquer based, and it dries almost instantly upon putting the grip on the bar. The hairspray, when dry, acts as an adhesive to hold the grip on. Just spray the inside of the grip and then the bar, then quickly slide the grip on before the hairspray dries.
Lastly, many of the grips that are imaged on these pages are Black in color, though they appear grey on the page. To show the relief on the surface of the grip, the F-stop on the camera was opened to allow more light, which gives them a grey appearance. This way you are able to see all the detail on the surface.