well, no myths here... of course you need carbs
when I ride (train or have a longer ride) I eat 90-100g of carbs (maltodextrin/fructose mix) per 1 hour (once i tried a bit more - I mess up my intake and had a mild headache for 15 mins- hyperglycemia?)
which means HALF A KILO of sugar for just 5-6h ride.