Drive Band Tension for Single Drive Spinning Wheels
In order to take full advantage of an elastic drive band on a single drive wheel, you want to set the tension correctly at the beginning to avoid most other adjustments as you spin.
We suggest you set the tension using the smallest whorl on the flyer. Increase the tension to the point that slippage ceases and you have positive drive. Normally you can hear when a drive band slips (more likely to occur on the down stroke of the treadle), so just increase till the sound goes away. Now, when you need a slower speed, just change the band to a larger whorl and most likely you will not need to make any adjustment to the tension setting.
But won't the drive band be tighter and don't you say elsewhere that this causes harder treadling? Tighter tension on a small whorl can be harder, but as you change to a larger whorl, you gain mechanical advantage and it will feel easier to treadle even though the band is now tighter. That is why you want to adjust and set the tension using the smallest whorl. Do this first. Optimize tension with the smaller whorl and the larger whorls will always be easier. Of course you can loosen the tension on those larger whorls and it will, indeed, decrease the force needed to treadle even more.