A spritz of water in the face from a water bottle is enough to deter a chasing dog. In all my years of riding, I have never met a dog that couldn't be deterred from chasing by spraying with a water bottle. If you had dog spray or bear spray that would 100% deter the dog. I don't know where you heard that it might not be effective. On a bike you don't need the dog to be completely incapacitated - just to interrupt it momentarily to get a few more meters ahead.
A club seems like a bad idea because of how close you would need the dog to get before you can use it, and a dog might mistake it for a stick that he is used to 'playing' with, and swinging the club would almost certainly involve compromises in bike control and balance.
A taser, even if you could be sure it would be effective, would be almost impossible to use while being chased while riding a bike at top speed.
A knife is an absurd idea. Maybe if the situation devolved into you lying on the ground being mauled by the dogs you could get a couple good stabs in, but unlikely.