It didn't bother me on the bike at all. In fact, the doc said cycling shoes were already pretty stiff so I could just wear those. I kept riding and swimming throughout the healing period. I was just very careful not to dismount with that foot and not to flex it.
How could a stress fracture start on the bike, which isn't a weight-bearing exercise? Maybe that's just where you noticed it first? Did the podiatrist explain that? Just wondering...
So I too was training for my first triathlon. I did it, six weeks later, and walked the run part.
"My predominant feeling is one of gratitude. I have loved and been loved;I have been given much and I have given something in return...Above all, I have been a sentient being, a thinking animal, on this beautiful planet, and that in itself has been an enormous privilege and an adventure." O. Sacks