A buddy of mine once remarked that you should get free speed whenever you can get it.
What's free speed? Well, it's not really free. It's just speed you gain from means other than physically improving for it. That means paying cash for it mostly. But at least you don't have to sweat for it!
Racing technology has improved greatly. Everything gets tested in wind tunnels to eeke out that last bit of efficiency. The basic idea is to slice through the air more cleanly and to reduce turbulence exiting out the back side.
Here are some ways to get free speed, and also empty your wallet in the process!
Aerobars help you be more aerodynamic simply because you're not upright against the wind. You can relax in a more aerodynamic position and revel in your arms not getting tired holding yourself up and just pedal! Some aerobars are also flattened like wings and are theoretically more aerodynamic than those made of round tubes.
Deep dish wheels and disc wheels are more aerodynamic than those with thinner rims. One disadvantage is that against crosswinds they can whip you around the road or even blow you over. On the other hand, disc wheels have been shown to have a "sail" effect against some angles of crosswind, giving you an actual speed boost. Cool!
Aero bike frame
Round bike tubes have been the standard on bike frames. Then somebody put flattened wing like tubes on bike frames and found out that made bikes more aerodynamic. Recent wind tunnel tests have shown other types of aggressive frame shapes can be more aero than others. Spring for that cool Trek Madone that Lance Armstrong rode or Specialized Transition TT Bike. Wow! Or "settle" for a Cervelo P3C.
Guess what: your head is a big wind drag! Buy an aero helmet and feel the air peel around your head in aerodynamic glory! Normal bike helmets can't compare.
The less poundage you drag along with you, the less energy you waste dragging your butt up hills or accelerating. This includes your weight and whatever you carry with you on your bike. Carbon fiber everything!
Loose, flappy clothes just hold you back. Buy clothes that hug your body. Get muscle compression benefits too! But watch out for cutting off your circulation - racing on numb limbs is not fun!
That little bento box sitting behind your handlebars has a slight aerodynamic increasing effect. It smooths out airflow off the stem area.
Some folks are making aero water bottles. Good for shorter races, but not that great when you're finishing bottles and tossing them on longer races. MIT cyclists have found that if you put a water bottle on the seat tube cage, it increases aerodynamics for those with non-aero seat tubes.
Definitely wear one on the swim. It makes you float higher, and your body more slippery. I wish they would make the new Speedo Fastskin Pro easier to take off - great for swim only races but terrible for triathlon transitions! Don't wanna rip a bodysuit that costs $400!
Have fun getting faster without working out harder, and feel your bank account drop like a rock!