Caution: Being excessively keto-adapted damages your carbohydrate adaptation. TANSTAAFL. To get the full effect of proper race nutrition like this, you may need to work on it for at least a week, maybe two.
I have not foound that to be the case.
I do agree that lack of glycogen will impair the ability to work at threshold but I have not found that my body will fail to absorb, convert or utilize CHO. There will be studies coming out showing keto adapted endurance athletes who oxidize fat at 2g/min!! What does that work out to 1080 calories per hour.