Leading as a Driving force
With one person walking or riding a the bike in front of the cows and the dog bringing up the rear you can move livestock quietly and calmly.
Cattle (and sheep) have quite poor depth perception because their eyes are more side facing than ours. By leading the cattle you help them to see things they otherwise might not. We have placed them in an artificial environment that is different to the one in which they evolved, nothing in nature is as straight and even as a well maintained field boundary. When you have gateway with another hedge behind it animals with poor depth perception can struggle to see the gap as there is not enough contrast between one uniform hedge and the one behind it. By leading them they see that you can go through it and they will follow.