Condensed Answer: The purpose of flared drop bars found on gravel bikes is to increase the bike’s stability when riding on off-road terrain in the drops.
The wider bars provide more steering leverage and make it easier to make technical maneuvers in the drops.
The flare is the angle formed between a line perpendicular to the flat part of the handlebars and the drops. (image above).
Riding In The Drops
Originally, drop bars were designed to provide a low, aero position for road bikes. By riding in the drops, the rider reduces the drag created by the body and makes it easier to reach greater speed.
Drop bars have two more benefits:
- Lower center of gravity (when riding in the drops, the rider is closer to the front tire. The lower center of gravity increases stability).
- High leverage braking (In the drops, the rider’s index and middle finger can reach the end of the brake lever and initiate braking from a highly advantageous position).
Drops and Gravel Riding
Drop bars are not as essential for gravel riding as they are for road cycling. Nonetheless, they’re still found on gravel bikes (learn why).
In the world of gravel, drop bars provide the same benefits (lower center of gravity, aero position, high leverage braking).
The added flare makes the bars wider. The extra width gives the rider more leverage and facilitates navigation on technical terrain.
This property is the main reason for the existence of flared drop bars.
Balancing Between Asphalt and Off-road
A gravel model is neither a road bike nor an MTB. It’s in-between. As such, it has to take characteristics from both ends of the spectrum and combine them into one.
Flared drops are one of those changes. Adopting drop bars as they’re found on road bikes is counter-productive because the bars are very narrow and do not provide the needed leverage for effective descending on tough gravel.
Of course, one can descend with standard drop bars on gravel too. I’ve done it myself, but having wider bars optimizes performance.
Another important characteristic of gravel bikes is the slacker head tube angle and shorter stem (two characteristics taken from the MTB geometry).
The head tube angle is the angle formed by the bike’s head tube and the ground. A slacker head tube angle positions the front wheel further in front of the rider and makes it easier to overcome obstacles.
Hence why MTB bikes have extremely slack HTAs. One of the tradeoffs is aerodynamics. A slack HTA makes the rider’s back angle more vertical and increases drag. In the world of road cycling, this is a problem, but in the world of gravel, the extra drag can’t outweigh the additional off-road capabilities that the bike gains via a slacker HTA.
The shorter stem found on gravel bikes is meant to make the steering in tight corners snappier and works better with wider (flared) bars. If both the stem and the bars are short, the steering becomes twitchier and overall unreliable. Thus, in this case, the wider flared bars save the day.
How Much Flare Is Too Much?
A 12-degree flare is the common starting point, but the flare angle can also be significantly more (e.g., 30 degrees).
The benefit of the smaller flare is the reduced shoulder stress, the compactness of the bars and the preserved aerodynamics. More flare, on the other hand, offers more leverage and is considered better for technical descents.
That comes at the cost of more shoulder stress, reduced clearance (higher chances of hitting an external object with the handlebars) and more drag.
Ultimately, however, the degree of flare comes down to personal preference and the terrain. For example, if the rider has wide shoulders and plans on covering rougher gravel, then a wider bar would probably suit him better.
FAQ: How much wider are flared drop bars?
The table below compares the widths of standard and flared drop bars.
|PRO PLT Ergo Carbon||36-46cm||Ritchey Comp ErgoMax||40-46cm|
|Zipp SL-70 Aero||38-44cm||Ritchey WCS VentureMax||40-46cm|
|Specialized Short Reach||36-40cm||NITTO RM-3 SSB||52-58cm|
|DEDA Piega 26||38-42cm||LEVELNINE Team-Gravel Di2||42-50cm|
|PRO Vibe Aero Superlight||38-42cm||Thomson Cyclocross||40-44cm|
Conclusion: The width of flared drop bars exceeds that of regular drop models by a notable amount. That being said, one can also find fairly narrow flared bars.
FAQ: Are there any additional benefits to flared drop bars?
Many people put flared bars on touring rigs because the added width makes it possible to fit extra large handlebar bags and opens the rib cage of the rider allowing for extra oxygen intake. Of course, the second benefit is a little exaggerated. One can get plenty of oxygen while using standard narrow drop bars.
Summary: What You Need To Know
Flared drop bars have the following pros:
- Extra leverage making descending on technical terrain easier
- Compensate for a narrow stem
- Lower center of gravity when descending results in more stability
- Extra width for the installation of wider handlebar bags
The downsides of using flared drop bars are:
- Extra drag
- Greater possibility of catching an external object with the handlebars as well as passing between cars
- Wrist and shoulder stress (if the flare is too much)