Have you got the rear section tethered to the fork arch?
No, what difference would this make?
FWIW several other reviews have mentioned it too (flex and bottom out buzz) – again, this will partially come down to how / what you ride. In terms of its job as a mudguard, it’s great and the ease of mounting is the best on the market (unless you have a bolt on version), but for me the noise it makes became irritating. I still have it so will give it another try.
Another question, what do people use for lift assisted riding where a full guard snags on front wheel mounted chairlift carriers? I’ve used a Rockguardz PG350 which provides a little more protection than the original Mucky Nutz type arch fenders, but has anyone found a better solution? I’ve ridden in some horrible Alpine weather when a fuller guard would be a real benefit.