I will only use Sulky invisible thread. But have only used it on top.
If your machine is like mine, when you wind a bobbin, you can't control the speed since it's automatic start and stop. When I was a kid, it was my job to sit there and wind the bobbins by hand! My Grandmother and Aunt both had treadle machines. But winding it by hand you could be more careful of not stretching the thread.