A guide to the terminology used for carbon handlebars
We cover the common technical terms used by handlebar manufacturers
There are some terms used to describe handlebars in general and carbon bars in particular, so we thought it would be useful to compile a list. Its not comprehensive, but hopefully it will make understanding what you are buying a little easier.
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Carbon fibre, modulus, K and Kevlar
The handlebars labelled as carbon are actually made from carbon fibre reinforced polymers of different kinds, using epoxy resins, polyester, nylon or other-based materials.
The carbon fibres are bundled together, combined and woven in different ways to give different strength and stiffness characteristics in the required directions.
The basic straight fibre is very strong when stressed along its length, but not so resilient to side stress. Engineering design has to take this into account and there are also omnidirectional carbon weaves available to give strength in all directions.
If you see the word "modulus" used it is referring to the stiffness of the fibre. However the tensile modulus is actually a number, so the use of "high modulus" doesn't have a definite meaning, unless accompanied by a number. Most fibres used are actually of medium modulus (33 to 42 MSI if you're a techie), as the higher values become very expensive and quite brittle.
You may also see labels like "3K" mentioned this simply refers to how many fibres are present per bundle, in thousands. 3K is actually quite common.
Also some carbon handlebars use Kevlar, but this is not a type of carbon fibre. Kevlar was patented by DuPont and differs from carbon in that it has an extremely high resistance to fracture as a result of being flexible. Hence its use in high impact protection. The combination of carbon fibre and Kevlar in a cycle component is intended to give rigidity from the carbon combined with fracture and failure resistance provided by the Kevlar. You will find that Zipp use Kevlar in some of their carbon handlebars, with an excellent record of resilience.
Theoretically this means that the handlebar has been constructed in one piece with the shell carrying the load required. This contrasts with a space-frame design, where an interior braced structure is covered with a skin.
It is also not the same as a handlebar which has been built up in layers, or one that has been made in more than one piece and then bonded together into a whole.
Ergonomic / Anatomical
These terms are used to refer to the various shapes, cross-sections and variations of radius designed into a handlebar to help a better and more comfortable handgrip and cycling position.
R50, R65, R75 numbers in a specification refer to the radius of the bends used. Currently Ritchey use this terminology to describe their bend designs.
Drop, Reach and Width
Drop refers to the vertical distance between the horizontal part of the bar and the lowest part of the drop. The related measurement of reach is the distance forwards from the horizontal bar to the front of the drop. Width is simply the width of the bar at maximum.
All these measurements are usually centre to centre.
These include the handlebar stem or the clamp ready to take a different stem, depending on manufacturer.
This refers to the use of variable wall thickness in the carbon handlebars, usually adapted for weight saving.
Names including Flex or Vibration or similar
These are usually manufacturers terms for whatever design they have implemented using carbon to reduce vibration in the handlebar.
Wing / Egg section
Manufacturers often give this name to the oval cross-section they use on the horizontal centre section of the handlebar. If you see "bulge section" this just refers to the larger central section in the middle of the handlebar.
This stands for carbon nanotubes, quoted by Easton in their bar specifications. These are tiny cylindrical threads, related to graphite, which exhibit some of the strongest tensile strength and elastic modulus properties available.
If you see a reference to this, it means one of the leading test laboratories for cycle components in quality and safety, where components are subjected to stress, impact and fatigue load testing.