In this image from De Lamiis et Phitonicis Mulieribus--a very old tome on witchcraft--shapeshifted witches ride the air on a stick, a more ancient concept than that of women riding brooms.
De Lamiis was written by German Ulrich Molitor in 1493. He was a law professor, and his book went into several editions, illustrated by woodcuts that were updated so it is possible to find different versions of the same image. I'll post two of those next time for comparison purposes.
Here's what Wikipedia has to say about Molitor:
He wrote one of the first books on witchcraft, De Lamiis et Pythonicis Mulieribus (The Witches and Diviner Women), published in 1489.
Although Molitor supported the death sentence for heretics and practitioners of witchcraft, from a moderate point of view for his time he considered that the Sabbaths were an illusion caused by the Devil and not a reality.
This image located in Alan C. Kors and Peter Edwards: Witchcraft in Europe 1100-1700.