Do aero wheels make a difference in road cycling?

This is a frequently asked question. Cyclists frequently believe that aerodynamic performance is only relevant to time trialists and triathletes. Unless you are a solo breakaway specialist, you may believe that aerodynamics are not critical to my racing success. Alternatively, if you cycle for recreation, you might conclude that the aerodynamic properties of a wheelset are irrelevant to me. This is demonstrably false.

Intended for Racers.

LOCATED IN THE PELOTON.

Even when protected by a peloton, aerodynamic wheels provide significant benefits.

Second, the wind is rarely directly ahead of you (a.k.a. a 0o YAW angle). When a crosswind is present, aero wheels become even more critical. The majority of us do not compete in highly organized echelons. When wind strikes a cyclist at a YAW angle greater than 0, the wheelset of a road cyclist becomes a critical limiting factor or benefit in terms of increased speed at a given wattage.

Acceleration and Weight of the Wheel

Another widely held belief is that road cyclists prioritize weight. The argument centers on rotational weight and how certain road racing events are stopped and started. This, however, is not true. When wheels were studied from a standstill to race speed, it was discovered that aerodynamics outweighed weight by a factor of 60:1.

Contribution of Bicycle Wheels to Road Speed vs. Frame Studies have shown that wheel drag accounts for 10% to 15% of total aerodynamic drag [Greenwell et al.]. Aerodynamic performance is more dependent on road wheels than on the frame of the bike. Purchasing faster wheels makes more sense than purchasing a new aero frame.

Carbon's Origins

Initially, alloy rims were used on road bikes. Aluminum wheels were seen on the world tour teams of the UCI. However, carbon wheels made their first appearance in the cycling world just before the turn of the century. As carbon road bike wheels improved in durability, professional teams began to adopt them. For a time, their initial high cost deterred amateur cyclists from using them.

In the 1990s, with the advent of carbon fiber wheels and frames and aerodynamic testing, it was discovered that aerodynamics may have a greater influence on performance than weight.

Depth and width of the rim

Previously, the rule was that the deeper the rim, the faster it was. However, we now understand that a fast wheel's aerodynamics are determined by a combination of width and depth. Through the use of computational fluid dynamics modeling and wind tunnel testing, road bike manufacturers such as FLO have been able to develop shallower, faster wheels than previous deeper wheel models. For instance, the FLO AS 77 is faster than the FLO A+C 90, a wheel that was already quite fast. When strong crosswinds are present, rim depth becomes critical, as shallower wheels allow riders to fight the wind less and maintain position on the rider's wheel in front of them.

Learn more about optimizing rim width and depth.

With the added benefit of new discoveries regarding the contribution of rolling resistance to speed, internal rim width and tire width have gained significance. When wider rims are combined with wider tires, a larger contact patch is created, resulting in decreased rolling resistance.