Now that I asked this question, I am finding a few tidbits about the use of chairs at treadle machines. Here's one that says "no wheels" but as CD said, it probably depends on how you treadle .... one foot or two:
"Start by setting up your space - make sure you can sit comfortably with your feet on the treadle plate and your back straight. You need a solid chair (no wheels!) and the machine should be on a firm base - thick rugs can get in the way of the plate's movement.
The chair should be at a comfortable height - ideally your arms should be parallel to the floor from the elbow to the wrist."
Here's one more little write about chairs that seems to support the above writing:
"A straight-back, stationary chair is a must for happy treadling. Find a chair with the right height so you can sew in an ergonomic position, but you're not bumping your knees on the underside of the cabinet. Having your treadle machine on a smooth floor is a big plus, but it's possible to treadle on carpet, too. You may need to put runners under the treadle legs to create enough clearance for the treadle pedal to move properly, but that's not a difficult fix. Furniture casters may do the trick - just experiment to see what works."
Last but not least, check out this entry about a dress making classroom in Kenya. Looks like my old school chairs from when I was a kid.
https://thesewingdivas.wordpress.com...in-mago-kenya/
OK, guess I have beaten this topic to a pulp. Sorry.