Condensed answer: Carbon handlebars can be coupled with bar ends only when the manufacturer has explicitly acknowledged this possibility. If this isn’t the case, it’s safer to combine the bar ends with handlebars made of material with greater clamping force tolerance such as aluminum.
The Problems With Installing Bar Ends On Carbon Handlebars
Carbon fiber has a relatively low resistance to clamping (squeezing) force. For that reason, it’s recommended to respect the manufacturer’s torque specifications when tightening accessories onto carbon components.
Hence why it’s mandatory to have a torque wrench which accurately measures the inserted force when working carbon parts. (You don’t need a professional torque wrench. One that goes to 7Nm is sufficient.)
If a bar end is overtightened, it can easily crush and damage a set of carbon bars.
Minimizing The Chances of Failure
The following steps can reduce the chances of carbon bar failure when using bar ends:
- Check the manufacturer’s specifications for compatibility with bar-ends.
- Use bars with reinforced end zones for increased resistance to compression force.
- Tighten the bar ends to the recommended specifications
- Use carbon paste to increase the friction between the bar ends and the bar and thus reduce the clamping force needed to keep the unit stable.
- Avoid using bar ends with poor clamping architecture requiring lots of tightening force.
- Use handlebar reinforcement plugs
Those are expanding plugs that go into the ends of the handlebars to fill in the space and increase the bars’ resistance to squeezing force.
One example of such plugs would be Specialized CNC Alloy Bar End plugs which are designed specifically to allow the installation of bar ends on carbon handlebars.
FAQ: How Much Torque Do Bar-ends Require?
In general, it’s about 4-5Nm. But it’s best to follow the data in the user manual that comes with the bar ends. Otherwise, you risk damaging the handlebars and voiding their warranty.
If you don’t have the user manual, you can search for it online or contact the producers or the local bike shop that you’ve bought the parts from and explain the situation.
Make sure that the representative understands the issue completely. Truth be told, sometimes help reps are a bit distracted or not familiar with niche problems such as this one. If you feel like the customer support is incompetent, seek a second opinion.
FAQ: Can I Use Ergon Grips with Carbon Handlebars?
According to Ergon’s website, all grip models except GP4 and GP5 are compatible with carbon handlebars designed to take bar ends.
Non-carbon Fiber Handlebars Provide the Most Security
At the end of the day, the only way to minimize the chances of a cracked bar due to the use of bar ends is to avoid carbon in the first place.
Even if you do everything right, carbon is a pretentious material that needs a lot of care and may crack even if you do everything by the book.
The only way to drastically reduce the chances of this outcome is to use an alloy bar. Aluminum has a much greater resistance to clamping force and will allow you to use any type of bar ends that you want.
The downside of this approach is the extra weight (not a problem for recreational cyclists) and the lower compliance (flex) of aluminum bars.
Summary: What You Need To Know
It’s possible to install bar ends on carbon handlebars when:
- The manufacturers of both components have specified the compatibility
- The ends of the handlebars are reinforced
- The user can install reinforcement plugs to lower the stress on the carbon bar’s walls.
- The user has a torque wrench to tighten the bar ends and the reinforcement plugs to the required settings.
- The user can apply carbon assembly paste to increase the friction between the bar ends and the handlebars.