In a critical situation, don’t try to reason with the unreasonable human who allowed their dog to come into your dog’s space. By allowing their dog to be unleashed where leashes are required, that owner has by default demonstrated a lack of concern for his own dog and yours. You may feel like screaming obscenities for their lack of care, but that wastes both emotion and time. It can also ramp the dogs up even more.
In Connecticut, dogs are not permitted to run at large except in the situation of hunting. Still, if the dog has vicious propensities and the owner still allows it to run at large and a person is bitten, the owner can be fined for up to $1,000 and is also liable for 6 months of prison unless the victim has abused the dog and provoked the harmful behavior.
Indiana is one of the states that has a restraint statute, which means that dogs must be restrained at all times. Otherwise, if the dog bites a person when not restrained the owner is subject to civil liability and criminal penalties. (Cite needed; definition of "restraint" needed; discussion of local Indiana ordinances forbidding dog tethering needed.)
There are also bicycle dog leashes, especially designed for people who enjoy taking their pet in a ride with the bike. The leash is an aluminum tube with a plastic coated cable which runs down through the tube. It extends out of the tube end a couple of feet to allow for ease of movement for the dog. One end connects to the bike and the other to the dog's collar. This keeps them safely away the bike.
Keep moving on a walk instead of stopping and chatting with others. While you and the other person are smiling and looking at each other, your dogs may be sending signals to one another that they are uncomfortable. Keep moving and stay focused on your dog’s body language. If your dog stiffens, growls, starts randomly sniffing or scratching, or you can see his hackles (among other warning signs that your dog is getting uncomfortable), do a U-turn and put something visual between you and the trigger upsetting your dog.