I fly fish my local canal for pike. I've found that with the growth of commercial fisheries there are far fewer anglers on there and I often have miles of canal to myself.
Walkers are not really a problem as they approach slowly and you become aware of them. Cyclists are a pain. They travel along the towpath at speed, often without making a great deal of noise. They are upon you quite suddenly. I have adopted the practice of always looking over my shoulder before casting. I'm just that extra bit more careful than when I'm on more remote rivers.
It's a pity that you are not allowed because there is some great fishing to be had.