It's hard to quantify how much time savings there would be without knowing a number of variables.

As a simple test, take the bike you road for the race and put it on a trainer and ride a 40k TT. Perform the same TT a week later on a properly fitted tri bike and see if there's any difference. Obviously this won't tell you about the aerodyamics of either bike but it will tell you whether or not you can ride faster on one bike versus the other.

I've heard some general numbers thrown around regarding wheels and helmets. A set of aero wheels will save you approximately 10 minutes over the course on an IM. An aero helmet will do the same. These are "rough" numbers that make some general assumptions like your current wheels suck and your current helmet catches wind like a parachute (which it probably does). Over the course of an Olympic distance race, we're now talking about a few minutes here, a few minutes there so you have to ask yourself whether spending 3, 4, 5K is worth minutes.

Considering you posted a 20+ mph average using a single speed, I think maybe just moving to a road bike would give you significant improvement without the need to spend an enormous amount of money. I guess it really depends on your goals though.

I want to clarify one last thing, you mention "deep-section wheels". There are wheels that are deep that are not considered to be aerodynamically beneficial. In order to see aero improvements, the wheels should be 50mm or deeper.

[quote=exitcreative]Finished my first sprint distance triathlon this weekend. .33 mile swim, 17 bile bike, 5k run: 1:24.11... and did it on a singlespeed Specialized Langster. [/quote]

Dang. I'm impressed. You did 17 miles on a single gear? I am all about the granny gear.

I'm new to all this, but you see such a huge difference with any kind of road bike vs. a regular old bike. So maybe give some road bikes a go first.

Dependig on the course and how well your gear size worked for you, the road bike might not be any faster at all. Stuart O'Grady ran a fixed gear for the prologue at the 2005 Giro, so it can definitely be done. However, if your gearing wasn't perfect, the road bike could be significantly faster (it's impossible to give even rough numbers without more details). A good TT bike with a good setup would be another 1-2 mph faster. Same for wheels. For an Olympic distance race, I would bet that you'd save in the neighborhood of 5 min with a good setup on a TT bike with aero wheels over a road bike without aero wheels. If you're getting things at cost from your aunt and uncle, you can get an Equinox from them for somewhere near $1500 I'd bet.

check google, but this is the order it goes from a standard bike, "bang for your buck" (speed)
best bike you can afford
now if it is a roady
tri suit
aero bars
aero helmet/wheels (depends and is debatable)
tri shoes

thats the main stuff now from here you are only talking less than 20 seconds per item over a 40k TT
aero frame
shoe covers
aero water bottle
and on the list goes

There is even a cost calculator which works out cost/time saving. Aero helmets cost a lot but they were up there with aero bars as the most affective for your $$$

I did some number crunching on this and based on todays economy and the fact that global warming is a hoax:
-2.24 switching to a tri bike
-.39 on the deep dish wheels.

Eric