It was a warm April evening, much warmer than it should have been, and the sun was coming down slowly over Chicago Avenue. Waiting at Milwaukee for the light to change, I argued with my girlfriend about which way to head on our bikes.

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Just then the light changed, and I took off going east on Chicago before she had a chance to speak again. A few moments later I heard the sound of hoofs on asphalt behind me, moving fast. Looking back I saw a horse and carriage, the kind tourists like to take in the summer, coming up behind my girlfriend. But something was definitely wrong. The horse was running at a full gallop, and the carriage driver, a petite young woman, was madly pulling on the reins and screaming something about a dog at the top of her lungs. At that point I noticed a brown pit bull coming full bore down the street behind the carriage, mouth foaming, chasing the horse intently, with no sign of giving up.

My first reaction was to get the hell out of the way and to make sure my girlfriend did the same. As the surreal scene flew by, missing us only by a few feet, I realized that if I could stop the dog there was a possibility the horse might slow down. If it didn’t, a collision with a car or a pedestrian was imminent.