Given you're not trained in any of these parts and they are mostly endurance sports, I would first assess your endurance.

Do each type of sport for 30 minutes and measure your distance. Don't do all three on one day, if you're untrained. Instead, take them a day apart or more if you feel sore. If you have access to a heart rate monitor, try keeping a steady heart rate. If not watch your breathing rhythm and try to keep it at such a level that you're still able to keep up a conversation (yes, that can be slow). We don't want you to strain yourself, we just want to see what you're capable off.

To measure your distance:

• count laps in the swimming pool,
• use GPS to track your running distance or run on a track
• use GPS to track your cycling or use a bicycle computer/speedometer

Using an app like RunKeeper is great, because it helps you track your progress and works for different types of workouts.

To assess the result, we can break down the Olympic record, which is 1:48. Here they spend about 20 minutes swimming, 60 minutes cycling and 30 minutes running. This comes down to:

• 4.5 km/hr pace with swimming or reversed ~13 min/km
• 40 km/hr cycling (using a much better bike than you probably own)
• 20 km/hr running

Most people have a part they're good at and one they're weak at. If you want to improve your end result, improving your worst part is probably a good idea.

So how does this relate to you? Well cutting all speeds into half gives you a nice ballpark figure to aim at for starters.

• Your cycling performance will depend highly on the quality of your bike and the number of hills you encounter. Cycling on a flat surface with a race bike will give a better time than using a mountain bike in the hillside.
• Given your history with cross country running, this part should be the easiest. At your age, it shouldn't take more than a couple of months or a C25K program to get you running at 10+ km/hr.
• Lastly swimming will probably be the worst if your untrained and unskilled. Untrained means swimming for 1 km will be exhausting, because of exhaustion you'll breath more, which will hurt your technique, which will exhaust you even more. So we probably don't have expect a great time here. No worries, your program will have to help you improve this and with regular training, this should improve rapidly.

Given you're not trained in any of these parts and they are mostly endurance sports, I would first assess your endurance.

Do each type of sport for 30 minutes and measure your distance. Don't do all three on one day, if you're untrained. Instead, take them a day apart or more if you feel sore. If you have access to a heart rate monitor, try keeping a steady heart rate. If not watch your breathing rhythm and try to keep it at such a level that you're still able to keep up a conversation (yes, that can be slow). We don't want you to strain yourself, we just want to see what you're capable off.

To measure your distance:

• count laps in the swimming pool,
• use GPS to track your running distance or run on a track
• use GPS to track your cycling or use a bicycle computer/speedometer

Using an app like RunKeeper is great, because it helps you track your progress and works for different types of workouts.

To assess the result, we can break down the Olympic record, which is 1:48. Here they spend about 20 minutes swimming, 60 minutes cycling and 30 minutes running. This comes down to:

• 4.5 km/hr pace with swimming or reversed ~13 min/km
• 40 km/hr cycling (using a much better bike than you probably own)
• 20 km/hr running

Most people have a part they're good at and one they're weak at. If you want to improve your end result, improving your worst part is probably a good idea.

So how does this relate to you? Well cutting all speeds into half gives you a nice ballpark figure to aim at for starters.

• Your cycling performance will depend highly on the quality of your bike and the number of hills you encounter. Cycling on a flat surface with a race bike will give a better time than using a mountain bike in the hillside.
• Given your history with cross country running, this part should be the easiest. At your age, it shouldn't take more than a couple of months or a C25K program to get you running at 10+ km/hr.
• Lastly swimming will probably be the worst if your untrained and unskilled. Untrained means swimming for 1 km will be exhausting, because of exhaustion you'll breath more, which will hurt your technique, which will exhaust you even more. So we probably don't have expect a great time here. No worries, your program will have to help you improve this and with regular training, this should improve rapidly.