Originally Posted by
Iride01
If you look at anything that is aero, you'll generally see a tear drop shape with the wider edge to the front. That wider edge is your tire, and the narrower trailing edge your rim.
Also, I have no idea how tubular wheels are spec'd. On a clincher rim, that would be a internal measure between the bead seat.
The tubular wheels I'm seeing spec an external width (because obviously there is no internal cavity).
Regarding aero, I agree with what you're saying on shape but the abrupt change where the tire steps down to the wheel I would think would disturb the air, although maybe not significantly enough to matter. Not trying to come off as argumentative, just trying to get some people's opinions.