I am a little bit prone to blood noses, from just blowing my nose it can start a bleed. Often i get one during a hot shower (no - not that type of hot!), it is more common during the summer (not s much shower ones).
I have never had one while cycling thank god, but I do worry. I push pretty hard sometimes as I am competitive, and have been basically stumbling to the ground after hill climbs and Individual Time Trials. Should I be worried? I have done over 6,500kms on my road bike alone without a bleed.