Sitting position

triathlon is a different animal and quite frankly you can sit wherever you feel most comfortable while still generating power.

some folks attempt to sit like they're sitting in a chair but a bike and a tri bike are different and you need to rotate your pelvis so as to sit more forward to generate power effectively and efficiently.

at least that's how I understand it, but I am the uber poseur slow rider.

Actually, that's very well worded.

Think about the way the sacrum/hips are shaped. When you sit "like you're sitting in a chair", your spine points up and forward. However, in a good tri position [like the one you posted, which is the most perfect tri position imaginable], the spine is pointed forward. So, you have to rotate the front of the pelvis down. this means that you have to put weight (and pressure) on your "taint" - duodenum, perineum, whatever you call it. This isn't designed to be a weight-bearing area, so it's highly uncomfortable.

Certain saddles exist to help with it - see the ISM Adamo Race and any of John Cobb's saddles (esp. the V-Flow).

Being forward allows you to use your quads almost exclusively on the bike, saving your hamstrings and glutes for the run. Also, it allows you to get into a more compact, and hopefully, aero position.

I like the word 'choda' for the taint:D

The problem with riding in the agressive position is that by using your quads in abundance your hammies will tighten and if you're not using a good stretching program or something else to loosen you could suffer later.

The hammies affect the lower back. Trust me.