First Mountain Climb in CO

I am wanting to take a trip to Colorado for road biking. A bucket list item for me is to climb to the peak of a mountain, but I don’t want to get in over my head for the first attempt. I am in good shape, but am from the Midwest where it is pancake flat everywhere. What would be a good first mountain to summit?

Edit: I am wanting to do a popular road climb and “summit” the road, not the actual mountain itself…