Wondering what your target should be? Family asking what time you'll be starting the bike? Here are some tips to help estimate your race times.
If you've got a coach, they should be able to give you a really accurate estimate of your splits. If you haven't got a coach, then consider your training times.
Look at your data, what's your CSS swim pace? What's your average swim pace over a similar distance?
For the bike leg, you can use Best Bike Split if you know your FTP. You can upload ride files and it'll estimate your CDA for more accurate calculations. Otherwise, you're looking for your average speed over a longer distance, but remember, you want to save some energy for the run. Cycle no more than 80% max effort for the bike, otherwise you're legs will fall off for the run!
And finally, for the run, remember you will be fatigued. So if you've run every sunday morning long run on fresh legs after a good nights sleep, then knock off a second or two per KM to account for the fatigue accumulated through the swim and bike.
Don't forget your transition times too - are you planning on a full change, this might take 5 minutes, or are you doing a flying mount and will take less than a minute?!
Other key factors:
Racing at a different temperature to where you trained may adversely affect your times. Take in to account that you may speed up or slow down depending on the temperature.
When it's hot, the air is less dense, so you move through it more easily. Over a long race such as an ironman, this can improve your time.
If you've not trained in the rain, and it rains on race day, you're likely to be more cautious on the bike, be less confident and therefore slow down.
This is an easy thing to overcome - train in the rain!
Practice your nutrition, make sure your body can cope with the type and amount of nutrition, otherwise you'll have several unplanned toilet stops slowing you down!