A carbon road wheelset is made by lacing spokes from the hub to the bicycle rim in a special pattern.The hub flange on a bike wheel holds the spokes in place on the hub.
The hub flange is usually machined from the same material as the hub body itself.The flange is usually no more than two millimeters thick.If it were an rider,most standard spokes would not fir properly.
Two flanges are placed at either end of the hub. The spokes from each hub flange create a triangle shape when they are attached to the center of the rim, so the wheel resists lateral force. The wider this triangle is, the stiffer the wheel will be.
High vs. Low Flange
Some riders prefer low-flange hubs, meaning the flange is only slightly larger than the actual body of the hub. This type of flange is usually used to save weight. Other cyclists prefer high-flange hubs that are heavier, but provide more lateral stiffness and better power transfer because they allow the use of shorter spokes.
Bladed spokes became popular on road bicycle wheels in the mid-1990s. These spokes had a flat, "bladed" edge (rather than a round profile), which created less aerodynamic drag than regular spokes. Many hub flanges were built with slotted spoke holes, so a builder could choose whether to use standard or bladed spokes when designing a wheel.