Ok, so people have been awesome telling me about bikes, so here's another question. Can you buy a road bike a little smaller so it fits you more like a tri-bike? (My bike shop says I should have a 60cm minimum, being 6'3).....but if a road bike stretches you out more, could I ride a 58cm with aero bars and raise my seat to the geometry of a road bike so it's comparable? So...I'm not so stretched out, use more appropriate muscles so I can go from bike to run with less stress? Would that be worthwhile or not?
I would try not to set-up a road bike for tri-bike geometry (if possible). Tri-bikes have different seat tube angles than road bikes as well as other geometry differences. A tri-bike is geared to place your hips at a different angle when you are in the aero position...if you put aero bars on a road bike, you close out your hip angle and that compromises strength and power. If you are going to get a road bike but you want to adapt it to tris, you may want to look at the road models geared for that such as the Cervelo Soloist or the Felt (Dual?).
A friend of mine has an article about this posted on his website about bike geometry. It is rather techy but informative. He is an engineer and just opened his bike shop a few months ago. I am sure he would not mind if you emailed him with a question: http://momentcyclesport.com/page.cfm?pageID=59
You can do some things to mimic some of the geometry. But, overall they are different as the previous poster indicated. That said, before triathlons, I was doing time trials on my road bike. I lowered the handlebars, flipped the stem, raised the seat, moved it forward a bit, and bought a bent seat post in an attempt to increase the seat angle as I understood the need to open up my hips as the previous poster indicated. It actually worked okay. I did several time trials that way and my first sprint tris. And you can do it if you can't afford a tri bike. BUT... do yourself a favor. Buy a tri bike with a proper fit. Even an entry level one. Why? Well, I found it was difficult to easily switch back and forth between road and tri setups. When I wanted to do group rides, I had to switch back as no group wants you along with aerobars. Plus, just having bar end shifters is great! You stay aero all the time. So, like I said, you can mimic some of the geometry and it will work to a point, but I'd recommend getting tri bike eventually.
Hey Tri Guy! I cannot honestly answer about the tri set-up....for over 42 races I have always used a traditional set-up "tricked-out" to race in my triathlons, including the World Championships. I did this to avoid the extra expense, but after all these years I CAN say that it is more trouble than it is worth. Seems that the geometry of the tri bikes is very specific for time-trialing, whereas clearly the traditional "softer" angle set-ups are better for overall training, etc. Certainly I can come close to what I perceive is the "correct" feel, but getting it tunes in a truly a real pain. Better, if funds allow, to get BOTH. Though I must admit, powering away from the group for a mile or two in the tuck position is worth a few nods!!...Best of luck, and let me know....I am sketchy about investing and getting fit on a modern tri bike. Ironman TH
There are some road bikes that have a more aggressive geometry, making them easier to switch to tri position (Kestrel Talon is one of them). It's an OK idea and works is you can't afford both types of bikes and want to have the ability to switch. To make the switch expeditiously, though, you will want to avoid re-routing your cables to bar-end shifters for the tri set-up. That means you will have to reach down to shift using your STI shifters. If you want bar-end shifters, then it's just too much work to switch it back and forth (but hey, if that's how you want to spend your time, it can be done!). My husband actually chooses to ride this model of bike as his tri bike and keeps it in the tri position at all times. It's one of the best, most comfortable fits he's found, so he sticks with it. It did mean making some adjustments (forward seatpost, shorter stem), but again, it's a very steep road geometry so it lends itself to this kind of switch. If you have to pick one type of bike and want to do both road and tri events, then this is one I'd recommend.