Just asked DH to weigh in on this, as an avid cyclist and dog owner. He said they’re both at fault (which was my first thought too).
I wouldn’t throw the ball for my dog in a place where she might across the path of someone running, walking or cycling. My dog has excellent recall but I’m also aware that trying to stop a dog chasing a ball is very hard and goes against the dog’s instincts. We will throw the ball on paths but only when the path in front and behind of us is empty. We won’t throw the ball anywhere near a busy path and if walking near one, we take the ball from the dog (she will walk holding her ball) in case she drops it and automatically goes for it.
Cyclist shouldn’t have been cycling through there. Yes, there are parks and commons that don’t allow cycling. There are plenty where I live but some cyclists choose to ignore that, which is probably why the council don’t police it. DH says he should have been more aware and if he didn’t hear the shouts from the woman, he can’t have been paying much attention (or his hearing was already affected by prior to the crash). From my point of view, the fact that he’s 18st is irrelevant. For one, DH has been almost that weight and managed to cycle at 35mph, with his average speed about 18mph. This guy has 40 years experience of cycling. If you do something repeatedly, even if you’re overweight, you can maintain a relatively decent speed. I’m overweight and prior to lockdown I could put walk most people because I walk(ed) a lot.