yet another bike question from a clueless rider

Price isn't really going to be the determining factor here. If you can find a tri bike that you can get into a comfortable and efficient aero position for 112 miles you will be faster than riding upright on a $2k road bike, or pretty much any road bike for that matter.

With that being said, given a pair of clip ons and a fast forward seat tube you can get into a pretty aero position on a road bike for much cheaper than buying another bike if cost is a concern.

thank you very much for answering

i get that, but how do you determine the effectiveness of your aero position - purely comfort and the ability to sustain it for 6 hours? - i mean if i do the aero bars and move my seat position on the road bike - how do i know if i am close to equalling what i would get from a tri bike?

thank you again

You can throw up some pictures of your position on your bike for people on here to critique, or you can head to a bike store and get a professional fitter to check out your position.

There are also some general "aero" standards for getting set up and positioned on a tri bike that you can find on the site if you searcht he forums a bit. These same standards can be applied to a road bike with clip ons, however not usually to the same extent due to limitations with the bike's geometry.

If you're looking for exact data and "proof" that your position is faster you can go out and try some real world testing on a familiar bike route (usually too many variables to be meaningful), Or you can spend tons of cash to get tested in a wind tunnel, which is most likely way more involved and expensive than you're looking to get.

Short answer: It's usually best to have a trained eye check out your position, and as long as it's comfortable you'll be good to go.

May I suggest some tiered goals?

Um... you're looking at doing an IM next year? And you won't have any time to research this in that time?

Hmmm.......?

What link are you going to for tri bikes this cheap?

Sub 12 hours is in the training and the person, not whether the bike is carbon or aluminum. If you have the time to train for an Ironman, you have the time to do some research on tri-bikes.

I would agree with this. It's the engine that does it. Also is this your first IM? if so why set a 12 hour goal? realistic or not (having no idea about your training volumes etc) that is a fine goal to have overall but wouldn't you be just as happy to finish it? Honestly if you come in at 13 hours because you had a bike malfunction or lost your nutrition on the bike/run etc, is that going to ruin your day and experience?

dukern: - this is the link....

http://www.beginnertriathlete.com/gear/

Vilano FORZA 4.0 Triathlon Bicycle Shimano STI TRI Bike

all i am asking here is lets assume i am going to do as much training as possible - it is my second ironman - i know what it takes and my first i did go under 12 - but just by 8 minutes and i had more time to train then then i will now. i was also 15 years younger. i know i will be close - but if 1 mile an hour buys me 20 someodd minutes - then to me it would be worth the investment. would a tri bike give someone that extra mile an hour and if so - at what level would you need to buy in at - this one above for $399 or much more expensive.

I second this suggestion. A full IM almost always presents unplanned complications to some degree.

What you have linked above looks no more than a road bike with clip on aero bars.  If that bike will save you 20 minutes, then your bike with clip-ons will save you 20 minutes.

That looks like a low-quality road bike with some clip-on aerobars.  Your current road bike would very likely be better.  Your best option if you are looking to save money is go to a fitter and have them set you up in as much of a "tri position" as is possible on your road bike (with clip on bars).  It wont be a great-fitting road bike anymore, but it will get you the most speed you can without spending too much money