TECH - Carbon Fiber Overview
Felt's carbon fiber grades and layups are the very best available

When we decided to delve into carbon fiber several years ago we did so because by then we had done our research and were comfortable with what material grades we wanted to use, what techniques we wanted to employ, and most importantly, we were confident in an end result we could produce. After all, plenty of companies were using carbon fiber and making great claims about it. That’s not enough. For us, it had to fit our mission:

“To design, develop, and deliver the best bicycles in the world. Period.”

A Little Bit About Carbon Fiber
Successfully used in aerospace and other industries for years, carbon fiber is now considered one of the ultimate materials to construct high-quality bicycle frames from. It is lighter than aluminum, stronger than steel and when properly laid-up, has the stiffness and snap desired in a true performance-oriented bicycle.

Carbon fibers are just like rope and display their greatest strength when under tension. To do its job properly, carbon fiber must be arranged in a structure and sequence so that loads run along its length. Carbon fiber comes in many different grades based on the material’s strength. The materials—or in carbon-speak the “modulus” —used in most bicycles are of intermediate grades. Modulus is a little like thread count on bed sheets—the more the merrier. As modulus increases the fibers gain tensile strength, but can also be trickier to work with. More expensive, too. Because it is challenging and costly, many companies steer clear of higher modulus materials. At Felt, that is all we use.

In bicycle construction, carbon fiber is generally extruded as sheets, fiber-wound into tubes or formed into complex shapes such as a lug. At Felt, we work with sheets of unidirectional fiber—picture long, straight black hair. These sheets are infused with resin (epoxy) and then cut to the shape needed. Working with carbon fiber in sheets gives designers control over the exact placement of material for almost unlimited freedom in dictating a bicycle’s strength, stiffness and ride quality.

All Carbon Fiber is not Equal
This is where Felt differentiates itself from others. Carbon fiber can be used to make bicycles through several different construction methods. At one end of the spectrum is the oldest method of building bicycles out there: lug and tube. This is the way steel frames have been built for more than 100 years. By this method, carbon fiber tubes are bonded to lugs, which may be made from aluminum, titanium or carbon fiber. The tubes are inserted into the lugs and the joint is glued together at the point where the tube and lug overlap. It results in a lot of extra material making the frame heavier than is necessary. It also ends up having a distinctly “flatter” feel because it is made up of so many individual parts.

At the opposite extreme is one-piece monocoque construction. In this method carbon fiber sheets are carefully and strategically laid into a symmetrically split CNC-machined mold (think waffle iron), a bladder is inserted, and the mold halves are closed and locked. The bladder is inflated, pushing the carbon fiber firmly against its mold, followed by a trip to the oven. When finished, the mold is opened, the bladder is removed, and the excess carbon fiber is cleaned. The result is effectively a perfect frame each time. Each frame size must have its own mold so manufacturing this way is considerably more complicated and expensive. However, the ride of a Felt monocoque frame is like no other. It has a lively, responsive feel unequalled by other bikes.

Felt Carbon Fiber Grades

Ultra Hybrid Carbon/Nano Tech - Our Ultra Hybrid Carbon with Nano Tech (UHC Nano) is our most sophisticated carbon fiber. This premier blend of specially selected carbon fiber material gives us precisely the strength and density where needed, incredible stiffness and vibration damping, for a ride like no other. It is one of the most elite uses of carbon fiber in the bicycle industry.

New this year is the addition of carbon Nano Tech to our UHC grade. This new technology makes carbon fiber structures even stronger and stiffer with virtually no increase in weight. It works by mixing tiny carbon fiber structures—known as nanotubes—into the resin used to hold the carbon fiber together. Think if it as mixing some other-worldly super-cement into a mold of rebar.

Tiny carbon nanotubes (CNTs) are so small an electron microscope is needed to see their structure. At approximately 1/50,000th the width of a hair and hollow, their name is derived from their size and shape. These mighty micros are the strongest and stiffest materials on earth as measured in both tensile strength and modulus of elasticity. Wikipedia™ says, “Carbon nanotubes are to steel what steel is to jelly.” What we do is add CNTs to the resin that holds the carbon fiber together. When combined with our UHC in models such as the F1, Z1 and AR1, CNTs increase the already ultra-strong characteristics of our premium grade carbon fiber and modulus of elasticity to an unsurpassed level. The result is an effective super-bond, one which provides both added strength and lessens the chance of damage during impact. Nothing is stronger or stiffer today.

Ultra High Modulus - Ultra High Modulus (UHM) carbon fiber is generally the industry standard for top-of-the-line carbon fiber road bikes. It makes for a super-strong, lightweight frame with an exceptionally crisp ride. Using our high-strength UHM formulation we are able to use less material in the frame. As a result, we are able to make the tube walls thinner while maintain the ride characteristics we want. Naturally, using less material results in a lighter frame and the large differential in wall thickness between the joints and the middle of the tube increases vibration damping, yielding a more comfortable ride.

High Modulus - With new advancements in carbon fiber technology, some materials and construction techniques become more affordable. Thanks to these developments we are able to offer frames made from High Modulus carbon fiber at price points once unthinkable for an advanced material. Very few companies are able to offer a full carbon fiber bike to compete with the Felt F4. Those that claim to use intermediate modulus carbon fiber which results in a heavier bike, one that lacks the sensitive ride quality found in our frame.

Today’s F4 effectively uses the same quality carbon fiber we used in the F1 when it was first introduced. As new grades of carbon fiber have been introduced, the price drops on the materials that have been available in the market, so we have been able to offer better quality carbon fiber at lower price points. Never before have you been able to get such incredible ride quality, low weight and strength for so little money.

What Does It All Mean?
It means that if you choose a Felt carbon fiber product you can ride it with the confidence, trust and ultimate satisfaction you would expect from a world-class product. It means it has been researched, tested and re-tested well before making it to your hands. It means it has been proven by some of the world’s top cyclists at the highest level of the sport—and will continue to be. And it means you will experience engineering superiority and performance for the ride of your life.