Need some advice. I am new to riding and have been running for years. I am going to compete in a biathalon consisting of a 2MI run, 10MI Ride and then a 2MI run. I have never ridden in a group, nor have I combined cyclying and running. Give me some advice!!

How often should I run versus bike to train? I have been putting in some miles on the bike (weather permitting in the NE) and love to ride more than run. Can I expect to be in good running shape by riding or is there no substitute for running to train for running? Should I try a group ride prior to the race so I don't kill anyone or myself?

What shoud I do to be most efficient during the riding portion of the race? Want to ride fast, but not sure if I should worry more about cadence or speed in order to save energy for the last running leg.

Any suggestions are appreciated.