Is Carbon Bad? Handlebars

In part 1 of our series on Carbon Fiber, we’re going to look at handlebars.  This is one of the most common places people look to upgrade their alloy handlebars, but is it a good idea? Sometimes…

The advantages of Carbon are clear: Stiff and light, they can be made in non tubular shapes for specific applications.  On road bikes, they are often made more aerodynamic with internal routing for shift and brake cables like with the 3T Aeronova Team Carbon Handlebar.  On mountain bikes, they can be made with varying thickness and fiber orientation to create flex where you want it, and stiffness where you don’t like on the Renthal Fatbar Carbon Riser Bar.  

Renthal Fatbar

Carbon fiber also does a better job of absorbing high frequency vibrations than Aluminum alloys used in handlebars.  Anecdotally, you can hear this when you knock your knuckle against an aluminum bar versus a carbon bar: the aluminum bar has a bit of a ring to it, whereas the Carbon bars deaden this resonance.  There are plenty of lab studies showing this phenomenon also if you need help sleeping at night.  

So Carbon bars are lighter, stronger, absorb vibrations better, come in shapes and sizes that aluminum do not.  There are, however, disadvantages to using Carbon in this application.  First is price: Carbon bars aren’t cheap.  Typically they are more expensive than their aluminum counterparts, aside from chinese knockoffs.  

Second disadvantage of Carbon handlebars is durability: in some cases Carbon does not have the same durability as Aluminum.  Because Carbon is a very stiff material, it can be brittle also.  While this is not usually a problem, when there are surface imperfections (i.e scratches from a crash), you can experience what engineers call rapid crack propagation.  Which looks like this at a microscopic level:

Rapid Crack Propagation

If you are running Carbon handlebars, closely inspect them after every crash.  Even if there are not obvious scratches from the pavement or trail on the bars, your shifters and brake levers could have rotated, causing a scoring of the Carbon surface (that’s probably what happened with mine, below).  Manufacturers recommend the bars be replaced after a crash like this for obvious reasons. Over-tightening your controls and stem on the Carbon bars are a common cause of failure, so make sure you follow the manufacturer’s recommendations for torque specs and use of assembly paste.  

Some people will point to pro cyclists running Aluminum bars to show that they are better than Carbon.  This not entirely true; pro cyclists are restricted by the UCI weight limit of 6.8kg on their bikes.  Running heavier handlebars, power meter cranksets, and even putting lead weights down the seat tube are ways the team mechanics get their ultra light carbon bikes UP to the minimum weight.  If you aren’t entering the Tour de France anytime soon, this probably doesn’t apply to you.  

So, is Carbon bad for handlebars? Sometimes.  If you’re a racer looking for every advantage as you put in big training miles, you will welcome the stiffness and dampening that Carbon bars bring.  If you are prone to crashing into trees and not chasing grams on your downhill mountain bike, Carbon bars may not make sense.  

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