There are a few customers like to know the benefit of 38mm vs 50mm carbon road bike rims.

The shape is almost the same for carbon tubular/clincher 38mm rims & 50mm rims . They are both aero wheels/rims.

The 38mm is lighter, but the 50mm is stiffer. The .38 have a bit faster jump and the .50 hold speed better. If you live in a pretty windy place, the 50mm could prove to be a bit much to handle in any sort of cross winds.

But the differences are small between these two rims. Rim / wheel stiffness / spoke count & tension/air pressure/rider weight & rider skill does effect ride quality also.

It depends a little bit on the conditions you'll usually encounter. If it tends to be gusty, even 38mm carbon rims may be a handful at times. If it's pretty calm, you may be OK with 50.

Some would go with 38mm set if I could only take one wheel to a race / crit. They seem more manageable & therefore use-able in more conditions, therefore more bang for buck in the long run.

Some buys a set of 50mm and a 38mm front. Ride 50mm on calm days and swap in the 38 if it is too windy.

Ask yourself what kind of riding you do and how your current rims/wheels serve you and buy the rims/wheels that fill a need.

Welcome to comment if you have any other suggestion. This will be good for all of us.