For the first 2 years of riding, I had 661’s. They did rub here and there but usually because I didn’t have them strapped right, on really long rides, I’d restrap them occasionally and this seemed to help. For the money, they’re great.
I found a good deal on KH percussions, I honestly like them better, no rubbing, definitely hotter but wearing shin/knee guards is not going to be very cool unless they have no back coverage (as unicyclists, we kind of need it).
I took an old pair of 661’s and cut the knee part off, when it’s really hot, I’ll wear just the shin pad, it works great and not as hot.
That’s what I did with my old 661’s! They were a hardshell plastic that was nice for bike trials, but overkill for muni.
I’m using the Race Face Flank knee/shin guards now. They’re pretty comfortable and stay in place; the only real drawback for me is that they don’t protect the back of my calves. That’s not a spot that gets hit hard, but I’ve scraped the pedal pins along my calf a couple of times.
I had a pair of those too, I didn’t like the no protection in the back of the calves. During Muni, we often slip off the pedals by going in front of them.