The decision about rim depth (so-called profile) of carbon road wheels has a big impact on bike performance. Deep rims, often called “more aerodynamic” wheels, can clearly increase riding speed, but they are slightly heavier and behave differently on climbs and in crosswinds.
On the other hand, shallow rims are lighter and feel more dynamic, but give less aerodynamic benefit at higher speeds. How to find the right balance? Below you will find current data and a practical guide. This information will help you choose the optimal wheel depth for your routes and riding style.
Aerodynamics vs weight – what matters more?
Is it better to focus on lower wheel weight or better aerodynamics?
For many years, it was believed that the lightest wheels give the biggest advantage in the mountains. However, recent independent tests show that air resistance already plays a key role at moderate speeds of 20–30 km/h.
What does this mean in practice? On most mixed routes, aero wheels with medium or deep rims are faster than ultra-light shallow rims.
The higher the speed, the more important aerodynamics becomes.
With carbon rims around 45 mm, you can save about 5–10 W at ~40 km/h. For a rider producing 250 W, this means about +0.2–0.3 km/h higher speed (which is tens of seconds over 40 km).
38 vs 60 mm
Choosing rim depth – guidelines
When choosing rim depth, consider the terrain you ride most often and your preferences. General recommendations below:
Flat terrain: deep rims (50–60 mm) give the best aerodynamics. On flat roads, deeper rims help you keep higher speed with less effort. Wheels around 60 mm are often used in fast stages and triathlon.
Rolling terrain: mid-depth rims (40–50 mm) are the most versatile option. They combine aero benefits with moderate weight and work well on both hills and flat sections. For most riders, 40–50 mm is the best range.
Mountain routes / steep climbs: shallow rims (30–40 mm) can be better on very steep and long climbs, where speeds are low and every gram matters. Lightweight wheels can save a few seconds on long climbs. However, even in the mountains, most pro riders now use ~40–50 mm rims, because time gained on descents and flat sections often offsets the small weight penalty. If the finish is at the top, shallow rims can be a better choice.
In practice, for mostly flat and rolling terrain, the best choice is a wheelset with ~40–60 mm depth. This setup gives aero benefits every day and still works well in occasional mountains.
If you often ride in high mountains and race on summit finishes, you can consider a second wheelset with ~30–40 mm depth. For most riders, one “golden middle” around 40–50 mm is the best solution.
Tests: speed and time differences
Results from internal tests done during development of the Evanlite collection.
TEST 1 – Flat ride (constant power).
On a flat section, 200 W was held on three wheel types: alloy (low profile), carbon 38 mm, and carbon 50 mm. On alloy wheels, speed was 30.4 km/h. With 38 mm wheels, speed increased to ~30.9 km/h, and with 50 mm to ~31.0 km/h.
The differences seem small (~0.5–0.6 km/h), but this is at constant power.
At 290 W (~37.5 km/h), the difference was already +1.2 km/h for 50 mm vs alloy wheels. This shows that deeper rims give more benefit as speed increases.
The test was done on a straight 5 km road, no turns, no wind, and protected by trees. Riding was at constant power (SRM power meter). The same tires were used for all tests — Continental Grand Prix 5000 28c with Continental Race butyl tubes — moved between wheelsets. Time savings per hour were calculated from real speed differences.
TEST 2 – Climb (4 km, avg ~7%)
Two Evanlite wheelsets were tested – 38 mm vs 50 mm – on a 4 km climb (~7%). Both rides were done at 270 W, speed ~16.5 km/h. The 38 mm wheels were only 3 seconds faster than 50 mm. This equals about 14 meters at the finish. Around 80 g difference in rotating mass had a very small effect (same hubs, spokes, and tires). The time would be recovered on descents and flat roads, where 50 mm rims keep higher speed thanks to lower air resistance. If the finish was at the top, the difference would matter more.
Test summary:
The biggest improvement comes when switching from heavy alloy low-profile wheels to carbon rims – you can gain even 1–2 km/h at higher speeds, which means over a minute per hour.
Differences between mid and deep rims (38 vs 50 mm) are much smaller. 50 mm is slightly faster above ~30 km/h, while 38 mm is slightly better on steep climbs. These are usually seconds per hour, not minutes. Both options work very well for most riders.
Crosswinds – are deep rims dangerous?
One common concern with deeper rims is crosswind sensitivity. It is true that deeper rims have more surface, so strong side wind can be felt, especially on the front wheel. This requires some experience and bike control. However, modern wide rim shapes improve stability.
Crosswind is a factor to consider, but there is no need to be afraid. For normal road riding, rims up to 45–60 mm are usually easy to control. Above ~60 mm (especially 80+ mm), wind effect becomes stronger, which is why these are mostly used in triathlon and time trials.
Triathlon and time trial wheels
In triathlon and time trial, the rules are different. Maximum speed on flat or rolling terrain is the priority. Riders often choose rims 60–80 mm, and even full disc wheels at the rear. This requires skill and good conditions. Deep rims above 60 mm are most effective at speeds over ~40 km/h.
Note: In road races, UCI rules limit rim depth to a maximum of 65 mm (from 2026).
Rider weight and wheel stiffness
Rider weight also matters when choosing rim depth, mainly for crosswind stability and stiffness. Lighter riders (<70 kg) are more sensitive to wind, so slightly lower rims (35–45 mm) can give better control. Heavier and stronger riders (80 kg+) often prefer stiffer, deeper rims (50–60 mm), especially during sprints and accelerations.
Modern carbon wheels from 35 mm and above are already stiff enough for most riders. You do not need very deep rims just for stiffness. A rider around 60–70 kg will find 35–50 mm a great balance. A rider around 85 kg may prefer 50–60 mm. The differences are small, and aerodynamics or wind will have a bigger effect than stiffness.
Summary – which rim depth to choose?
Check your terrain: For flat roads, choose deeper rims (50–60 mm). For rolling terrain, 40–50 mm is ideal. For mountains, consider 30–40 mm, although ~45 mm can still work well.
Consider your weight and experience: Lighter or less experienced riders should avoid very deep rims in strong wind. Heavier or more experienced riders can use deeper rims without losing control.
One wheelset for everything? If you want one universal setup, choose 40–50 mm. It gives a clear speed benefit on flats and still works well on climbs.
Two wheelsets option: If budget allows, use one shallow set (30–40 mm) for mountains and one deep set (50–60 mm) for fast riding. You can also mix – for example, a shallower front wheel and deeper rear.
Confidence matters: The fastest wheels are the ones you feel comfortable with. If deep rims make you feel unsafe, they will reduce your performance in real riding.
Finally: weight is no longer the main factor – the full performance package matters. Modern wheels are light, stiff, and stable. Most riders will feel a big improvement when switching to 40–60 mm rims compared to basic shallow wheels.
If you are not sure which wheels are best for you, contact us. Describe your riding style and routes, and we will help you choose the right setup.
Fill out the form
You can also check our Evanlite road wheel categories and choose a set that matches your riding style.
See more
