Because glucose is the body’s preferred source of energy when cycling, you should eat foods that are high in carbohydrates (and that are also easy to digest) on a long bike ride.
Sports gels, chews and drinks, honey sticks, bananas, and even jelly beans are all popular, easily digestible choices for topping up your glucose supply on a long bike ride 
. Raisins, chopped dates, and mini-pretzels are also good sources of energy that can be used to refuel during a long ride but should be tested out before race day.
It’s important to start refueling early to keep your energy levels up, because if you bonk there’s no bouncing back. On average, both the glucose you have on board at the start of a ride and your glycogen stores will be depleted after 60-90 minutes of high-intensity cycling (>80% VO2max) or 120 minutes of moderate-intensity cycling (~65% VO2max), which is when bonking sets in .
You should begin refueling around 45-60 minutes into a long ride. To maintain adequate energy levels while riding, you’ll need to consume about 30-60 g/carbohydrate/hour. Many cyclists prefer to split their intake into 20-minute increments to minimize GI discomfort.