So... when I start to get really pedantic about weight on the bike, and the extra weight I could get rid of when going up a hill...

well... how much does hair weigh? Mine is quite thick and is longish, sitting between/past my shoulderblades...

And what about on a hot day when I sweat - or a wet day when it rains?

How much does wet hair weigh?

Should I chop it all off again?