I've broken the same bone in both my wrists too, mine from motorcycle accidents though, hehe, tiny drop at 15MPH and I break my wrist.
I come off at 110MPH and walked away, just goes to show you never can tell. I plan on buying wrist guards with my bocks off the site, I already have knee/shin and elbow/forearm armour from mountain biking, so I should be all set to push it a little and get my first fall in, as I am yet to do!