Whereas sugars are not necessary for cycling in general, they are necessary to elicit top performance on long challenging rides. Pros struggle with ever more elaborate sugar mixes, trying to maximize calories ingested per hour. I've helped many riders who were getting dropped late on long hilly rides. I hand them my bottle of maltodextrin and say, "Take 6 swallows." Fixes them right up, though only for as long as the maltodextrin lasts. "You can't put out what you don't take in" is the rule on long hard rides, speaking of converting calories to kilojoules. The battle is to move as many calories per hour across the stomach wall. That maximizes one's total power output per hour. Sugar is the fastest, and some sugars or sugar mixes are faster than others. Of course this is only relevant for riders whose training allows them to hold relatively high power outputs for long periods of time. Relative to what? Relative to their FTP. It's not a question of talent. Even the talentless can achieve remarkable results by optimizing their fueling.

Of course this is all nonsense for the vast majority of people who ride bikes, but it makes a big difference for those who want to ride long distances as fast as they can. "Needed" is the crux. Not needed to ride a bike, just needed for top performance on rides of over a certain number of kilojoules, which number varies with the individual and their training.