mrPAC, i send you my heartfelt condolences -- been there, done that, too many times (in fact, stress fracture recovery is the basis of my screen name). my very first one was in my tibia, although that was in a former life, so to speak, when i was a dancer in college. since i began running, i've had three (femur, calcaneus, and fibula). in all cases, i was able to bike ride without pain (although with the fibula it took maybe three weeks, since at first it really hurt to clip into my pedals). so i rode -- a lot. enough to retain my fitness. swimming is also a great thing, and if it doesn't hurt to go pool running, and if it doesn't make you go bonkers with boredom, go for it.
i've not quite hit menopause (age 48), and probably wouldn't have known that i have low bone density if i hadn't been putting the stress on my bones that i was, so the blessing in disguise is that i received an early diagnosis and have hooked up with a good endocrinologist who also is a noncompetitive triathlete, but active enough to understand my mindset, which makes all the difference in the patient-doctor relationship. getting back to the matter at hand, the rule of thumb with stress fractures is to not do whatever hurts the injured area. that's it. and to be patient. i took 2.5-3 months off running with each instance and then resumed as follows: 3 min run/1 min walk on grass, repeat three times; do this every other day for a week. having an "awareness" of the site during this tryout is okay, but pain is not. it's a great exercise in listening to your body. it has been recommended to ramp back up very very cautiously thereafter, but i've sorta jumped right back in after a week or two of extreme care, although i've kept very attentive to the return of pain.
i wish you all the best in your recovery and do continue to post here for encouragement. oh, what i didn't mention above is that i gave myself permission to feel sorry for myself, but only for at most a week; then it was time to move forward, find something else to keep me happy, and know that i'd heal.