I've heard 40/30/30 c/f/p as a standard ratio, with a higher allowance for carbs in a very active person. I find that I usually eat about the 40/30/30 proportion with on-the-bike snacks/drinks excluded. Those are almost totally carb-based & help me maintain my energy while riding.
I wouldn't lower my fat from 20%, or raise my carbs from 60% personally. What makes you consider this? Fat gets a bad rap, but it doesn't make you fat, and I find that when I eat fats that the food I eat 'sticks with me' longer and my hair and skin are healthier.
Carbs are important to maintain your energy, especially when exercising, but having too high a proportion of carbs in your standard diet is a good way to feel hungry again in short order, and it's not just on a daily basis but on a meal-to-meal basis that a good balance is important.
An old roommate of mine used to get on my case because I could drink whole milk, eat food with real butter, etc. and stay skinny (whole milk matches the 40/30/30 proportion almost exactly) while she ate very little fat and gained weight. Problem was, I was getting a reasonable number of calories, and feeling satisfied after meals and snacks, and she was eating a jumbo-bag of red vines in a sitting and feeling hungry after.
One thing that macronutrient guidelines don't take into account is a truly balanced diet. A good rule of thumb that I've heard for that is trying to eat a diet as varied in (natural) colors as possible. More than anything I recommend staying away from processed/refined foods.
Anne