Many races provide ample aid stations and tech support, but you’re much better off taking control of as many things as possible since the likelihood that your breakdown (engine or machine) will happen near someone who can help is small. Carry your own food and drink. Pack a spare, tire irons and air, and a set of allen keys. I also like to take a small chain tool. Finally – learn how to change a tire and perform simple maintenance on your bike. Take control!