I didn't have a speedometer/cycle computer to verify my actual speed, but I know I got going pretty quick a few times, on the old Cannondale. Especially coming down the mountain, from Golden Valley, AZ to Bullhead City, AZ, which I call 12-mile hill. 😁 That has a few areas where the grade levels out some, but never level like flat ground, it's all downhill. 😎
I've never even tried riding up, but I've seen a guy do it, on a road bike. He was way stronger than I am, like a pro athlete.