When I'm out on the bike I've found that I can keep going for approx 50% longer if the temperature is below freezing.

It seems that the energy I use to prevent myself from overheating seriously eats into my energy reserves. A typical weekend ride may last 4 hours at which point I'm ready for home, whereas ysterday I kept going in sub zero temperatures for more than 6 hours.

I always keep myself hydrated and never knowingly wrap up too warm so the only conclusion I can make is a third of my energy reserves normally get wasted with just maintaining normal body temperature.

Do any experts in this field have any opinions?

Cheers

I don't think you use energy in stopping overheating – more likely you use extra energy in cold weather I would have thought.

More likely you overheat / dehydrate when it is not so cold I would have thought