One of the ways I learned to understand what 'on the bit' really meant was by putting a pencil in my mouth, both ends sticking out the corners of my mouth. My driving instructor did that. Then he tied a piece of string to each end of the pencil and he asked me to hold the pencil with my lips. Weird, huh? Then he proceeded to 'cue' each side of the pencil ('bit') to show me what the horse feels and how the bit actually works in the horse's mouth. It also gave me insight into how much contact I had with my horses. The idea, he told me is to get your horse(s) to hold onto the bit, so that he can feel your cues. If the horse is in fact holding onto the bit and you have nice contact, your slight loosening of the rein on the right side, will make the horse naturally move to the opposite side....that is, "he'll follow the bit". Remember, the pencil? Loosen the string on the right side, and the tendency is to go to the left if you are doing it correctly. We used to practice driving toward a perpendicular fence. As we'd get closer to the fence, the horses ears would start 'wiggling' as if asking me, 'which way are we going to turn?' When the horses would start turning in one direction, I'd cue them into the opposite direction, by moving the lines in the opposite direction of the turn. This does two things: It teaches your horses to wait for your cue. And, if you're holding the lines in one hand, it teaches you how to make the turns 'Achenbach style'. I never learned what driving Achenbach meant until recently. But I learned the technique early on, when I first started driving a pair. What you are doing when you drive Achenbach, is 'tightening one side of the bit and loosening the opposite side'...equally. Assuming the horses are on the bit, they will follow your cue. The pressure and lack of pressure are equal if both lines are held in the same hand. Your turns will be smother this way and I think your horses will be happier. Having said all this, it's not as easy to do as it is to say or write about it. Takes lots of practice. IMO this is a better way to drive, either single or in a pair. Driving more than I a pair? I have no clue....haven't been there and haven't done that! and don't plan to anytime soon. Incidentally, every time I have given riding lessons, I started by putting a pencil in the student's mouth so they can understand what the bit does and how your hands affect it's movement. Another very good source for understanding what 'on the bit' means is Deb Bennett's "Secrets of Conformation" books (I think that's the name). I think the three books were printed by Equus Magazine while she was writing for them. Don't now if they're even in print anymore. I believe Achenbach makes it easier for the horse to want to 'get on the bit' because the tension is always even and smooth. That isn't always the case when there's a rein in each hand. Working animals usually know their jobs so well, they follow by habit or by voice. A Mennonite friend told me of an instance when his dad was in the field working, when something broke on his horse-driven machinery. He told the horses to 'whoa', hopped on the bus as it went by and went into town to buy a replacement part. When he came back his horses were waiting for him. While driving working animals doesn't require the same type of efficiency as competition or pleasure driving, especially if you go out on the road, it all depends on what you are trying to achieve and what your driving goals are. In my view, Achenbach and 'getting your horses on the bit' go hand in hand. Hope this helps someone. Helen