Knee Warmers that don't creep down?

[GLC1968]

They do have a rather short inseam at 6", so maybe that's part of the problem.

This is likely a contributor. I have PI knee warmers and I find that if I wear them with either of my two pair of longer PI shorts (8" inseam) then they work great. If I grab the wrong shorts (my 6" summer shorts), then the knee warmers will work their way down my legs. My thighs are NOT small...so it's not a matter of my shorts or the warmers being too big.

I think that the longer shorts give them enough extra overlap that when my knee is bending repeatedly, they don't work their way out like they do with the shorter short.