Yeah what the other posters said...

Don't let fear stop you from doing something you love.

Shortly before I left Austin (TX) a woman was murdered on the Barton Creek Greenbelt. At the time I rode and/or ran that trail at least 3 times per week. Sometimes with friends, but often alone.

After moving to this area, Jill Behrman was abducted (and killed) while riding her bike. You can read all about the case if you Google her name.

I still ride alone.

It is a choice I make. I have decided that the joy and the health benefits I get from riding out-weigh the risks.

It doesn't mean that this is done mindlessly, for more tips on riding alone check out this thread.