This was in a sprint tri I did in Spain way back when I was on active duty in the Navy. Got out of T1 and am a couple miles into the bike. There was a pack of 4-5 of us in the lead group. Then I heard a buzzing sound. I thought someone’s bike had a problem. I looked around, and a guy on a mountain bike with fat knobby tires had caught us. Wow! Good for him I thought. But it was short lived. He stayed with us for a mile or two. But the extra energy it took for him to catch, and stay with us pooped him out and he faded out and dropped back.
Dan