Doesn’t really help you but I remember when I used to have a paper round there was one dog who’s owner was happy for it to wander the street – I had to stop to deliver 1 paper (to their house) and then I used to frequently have to pedal for my life and then rapidly dismount and jump over the next persons wall to avoid being bitten by the bloody thing.
I love dogs, it really upsets/annoys me when owners let their dogs do things that like. One of ours is a bit nuts, and doesn’t always come back straight away when called if he gets distracted but I know he’s safe to be let of the lead because he doesn’t aggression and always runs away from things instead ‘cos he’s a wimp.
Our other dog is normally fine but has bitten my dad once (it was his own fault for trying to steal his food!), but we’re always a little bit more careful with him around people or other dogs when we’re out just in case.
As far as repelling dogs when you’re out on your bike – either pedal faster or dismount and hope for the best I think might be your best shot!