Oly is a bit longer, so I'd shoot for tempo (1 hour race pace) pace for first run. Most people can fake a 5K after 30 minutes of biking, but the hourish bike/10k requires a bit more pacing.

Edit: I'm doing a du this weekend that has a 3 mile first run, 1.8 mile second run. Much more civilized than having to run the whole 3 miles on the 2nd lap....