This is a sentence that has the missing verb in it. Verbs are part of speech that is used when we are describing an action, state or occurrence.
The word ''ride'' is an irregular verb and it is considering controlling the movement. In that way, Sara and Jane are controlling their bikes riding them to school every day. In this sentence, bike is used as their transport to school.
This verb can be used in, for example, ride a car, ride a horse, ride a bike and more.
