You'll hear from a lot of brands that disc brake wheels completely increase wind resistance. this is not right. Because the disc brake wheel set has an extra disc, there is an extra rotating surface, and the wind resistance generated at 45km/h is not much. Considering disc brakes provide better, all-weather braking performance, that's not a big deal.

But is it that simple? No! As mentioned before, the hub also creates wind resistance because it is a cylinder. The bigger the cylinder, the bigger the wake; the bigger the wake, the bigger the drag. Generally speaking, disc brake wheels will have a larger front hub housing to handle the braking torque generated by the disc brakes; and there will be more spokes than rim brake wheels. Combining these two points, the disc brake wheel will generate more wind resistance.

However, due to the neater crown part of the disc brake frame and the higher integration of the rim brake, it will recover some losses, but not enough to make up for the loss on the wheelset.

Therefore, after comprehensive calculation, disc brakes will lose about 1 watt advantage over rim brakes, which is a very small gap. In terms of better braking performance than disc brakes, it is completely negligible.