If you can find a cycling group in your area, you might pick up some good tips and get some riding buddies. Bike racing requires excellent handling skills at high rates of speed. You have to walk before you can run,er, race (har-de-har-har, I'm cracking myself up again)

Running and cycling use different muscle sets, so cycling might be more challenging physically at first. Also, you said you fractured your sacrum. Has your bike (especially road bike) been fitted for you? An ill fitting bike might be problematic. Make sure your bike fits and that the saddle is comfortable. Don't rule out men's saddles. Many women's saddles are quite wide to accomodate a broader pelvic bone structure. If you're like me and you've never had kids - or just have a small frame, women's saddles are like wearing a diaper.

Welcome to cycling and to Team Estrogen. There is a wealth of knowledge here and a bunch of really great women.