I recently watched some spinning videos (on my iPad, LOVE that thing!) including Popular Wheel Mechanics by Judith MacKenzie. She advises people to get to know their wheels by seeing the range of yarns that you can produce with it using your default spinning speed and adjusting the whorls (or pulleys, as Judith calls them) and tension.
I decided to do just that with the Lendrum. I used beautiful Polwarth fiber that I combed and dizzed so that the fiber and preparation would be consistent. It was a neat exercise.
I used only the regular flyer with its three whorls. I let the yarn ply back on itself as soon as it was pulled off of the bobbin. I tried to maintain my usual treadling speed (which is pretty fast) and let the whorl and the tension setting dictate the size of the yarn. My drafting speed did vary a bit.
You can see that there is quite a range of yarns from that one flyer. The top yarn was the thickest that I could spin because the fiber had been dizzed to a fairly small diameter. I didn't draft it very much while spinning. Could I have spun a thicker yarn with just this flyer? Maybe a bit but I think I would have to consciously slow down my treadling to do so. The plying flyer, which I didn't buy, would likely make the job easier because the whorls would be larger.
I didn't have any trouble at all producing the finest yarn because the lovely Polwarth fiber drafts out beautifully and because my hands really, really like fine spinning. I have the fast flyer but didn't use it for this experiment. Because I treadle quickly, I don't really need the fast flyer for spinning wool but it is great for cotton. Lendrum does make a very fast flyer but I can't imagine ever needing it although some people like it a lot.
This was a very useful exercise and I recommend it. One of these days I'll get around to repeating it with my other two wheels.