The question of the correct rim depth for road bike wheels requires thorough research, especially in the era of carbon fiber material. In the old days of alloy, rims were narrow and flat, and weight was the primary consideration for all cyclists. But then carbon fiber took over because the new wonder material was lighter and stiffer than metal.

It was also easier to shape, meaning designers spent many hours in wind tunnels perfecting the ultimate aerodynamic rim for road cycling. Aerodynamics have always been important on the road, where air resistance and energy requirements increase exponentially to maintain speeds above 25 km/h. Average speeds of 50 kilometers per hour (30+ mph) are reached in competition, not to mention breathtaking alpine descents at twice the speed. Aerodynamic rims play an important role here.

At first glance, viewed from a distance, the modern professional peloton looks as if it is rolling on fat bike tires. But these days tires are still narrow – 23 or 30 mm. A closer look shows that deep carbon fiber frames give the impression of voluminous tires. These wide carbon fiber edges are the result of intensive aerodynamic development and resemble a teardrop in overall cross-section, rounded off at the front by the curved profile of a tire. An extended teardrop profile has different wind-resistant properties compared to a flat rim. The cross section can be V-shaped, with a sharp edge where it meets the spokes, or U-shaped, like a stemless wine glass. There is also a hybrid combination of both profiles, which is preferred by some aerodynamics experts. The deeper the better, they say – and the ultimate depth is found on a rear disc wheel, where you could say the rim profile ends at the hub end!

How to choose the right depth for road bike rims

The question of the correct rim depth for road bike wheels requires thorough research, especially in the era of carbon fiber material. In the old days of alloy, rims were narrow and flat, and weight was the primary consideration for all cyclists. But then carbon fiber took over because the new wonder material was lighter and stiffer than metal.

It was also easier to shape, meaning designers spent many hours in wind tunnels perfecting the ultimate aerodynamic rim for road cycling. Aerodynamics have always been important on the road, where air resistance and energy requirements increase exponentially to maintain speeds above 25 km/h. Average speeds of 50 kilometers per hour (30+ mph) are reached in competition, not to mention breathtaking alpine descents at twice the speed. Aerodynamic rims play an important role here.

At first glance, viewed from a distance, the modern professional peloton looks as if it is rolling on fat bike tires. But these days tires are still narrow – 23 or 30 mm. A closer look shows that deep carbon fiber frames give the impression of voluminous tires. These wide carbon fiber edges are the result of intensive aerodynamic development and resemble a teardrop in overall cross-section, rounded off at the front by the curved profile of a tire. An extended teardrop profile has different wind-resistant properties compared to a flat rim. The cross section can be V-shaped, with a sharp edge where it meets the spokes, or U-shaped, like a stemless wine glass. There is also a hybrid combination of both profiles, which is preferred by some aerodynamics experts. The deeper the better, they say – and the ultimate depth is found on a rear disc wheel, where you could say the rim profile ends at the hub end!

Flat rims

Flat rims are lighter and easier to accelerate even in alloy because they have less inertia. This can give them a 1/100th of a second advantage over the last 200 meters of a sprint. On a route like a large mountain pass, where the peloton is traveling uphill at speeds of less than 25 km/h, aerodynamics are not a problem. A flat, lightweight rim helps the cyclist fight gravity. But it offers no advantage on the subsequent rapid descent that usually follows a steep climb. On a track that ends at high altitude, such as the famous Alpe d'Huez in France, a deep rim profile would be a handicap. But on flat terrain, when fighting the wind, it far outperforms a flat profile, even if it weighs more.

Which rim depth is suitable?

Like so many other decisions in life, getting the right rim depth requires a compromise. For the hobbyist who enjoys Gran Fondo, a rim with a depth between 45mm and 55mm is a good choice.

It offers a happy medium between the extremes of comfort, aerodynamics and stability. Especially in the middle of a crowded peloton – even if there is a crosswind. Such a rim also provides greater durability for the rider competing in both competitions and training on the same wheelset. The cyclist who lives and competes in a mountainous region could choose flatter rims. If a heavier dedicated competitor is looking for the ultimate rim for a flat course in calm conditions, they can go to 86mm at the rear - and go for something less adventurous at the front if their course happens to cross a crosswind.

How to choose the appropriate rim depth at ICAN.

ICAN offers performance wheelsets with a wide range of rim depths. This range of high quality wheels covers extremely specialized purposes - as well as more general cycling. Regardless of the two-wheel discipline an enthusiast follows, the ICAN catalog has a wheelset with a rim depth to satisfy every customer. For mountaineers, there's the Aero 35 Disc for $645; plus 50 mm and 55 mm versions. For the professional time trial competitor, the top-of-the-line DT Aero 86 costs $1085, and this series is also available for the peloton in depths of 50, 45 and 40mm . For beginners on a budget, a good all-around choice would be the ICAN 50mm 700c Standard Clincher Wheelset for $490.