The ability to digest fats depends on the % of Vo2 your riding at. Higer %, harder to digest fats. Also digesting fats is something that can be trained to improve.
You're thinking of metabolising fats. 'Digesting' them is still a slower than carbs no matter what pace you're doing. Faster pace makes everything harder to digest.
The ability to digest fats depends on the % of Vo2 your riding at. Higer %, harder to digest fats. Also digesting fats is something that can be trained to improve.