I think it depends on what you’re gonna use them for
- If you’re just general road riding - 5.6s. they’ll handle more wind conditions.
- If you’re racing triathlon - 7.8s obvi
- if you’re racing flat crits and you want to optimize - 7.8s
I have a set of Roval CLX50 and I’ve definitely felt squirrelly in the wind with them. The 5.6s seem pretty stable in the crosswind - I even raced then in like 40mph winds where they cancelled the later waves due to the high wind and they never felt out of control.