Hi, whoever's left here!

I'm a swimmer-turned-runner who has recently taken up triathlon.  About 5  years ago, I bought a road bike strictly for cross-training (a Cannondale R500).  Earlier this year I competed in my first triathlon, a half-ironman, and out of necessity I rode my road bike, which I had retrofitted with a cheap set of aerobars.  It went okay.  I'm looking at doing a few Ironman races next year, and I'm wondering if I would be stupid to use my road bike for these longer races or if people regularly do that.  I'm a poor grad student, so a tri bike would be a pretty significant purchase for me right now.  Thoughts?  Experiences?

I guess you're question got lost with the latest entry dump going on. You plan on doing a FEW Ironman races next year? Wow, that's quite a rapid ascent. Careful of the overuse injuries! As for the bike, you'll have to answer that one yourself, and your comfort level. Be sure to get an expert on bike fit. That is probably the single most important thing that you can do when on a bike search. Just my opinion, I'd go for the tri bike and the aero benefits. You can do an interner reaearch on time saving per each piece of tri-gear, from front to back, including helmet. Saving not only time, but energy. Remember, you will still have a marathon to run. As for the search for a savings on a bike, put out some feelers, maybe talk to a tri-club, they could be a big help. Luckily, you'll find someone who knows someone who has recently given up the sport. Or just wants to get rid of a bike that is gathering dust. I would also post your question on slowtwitch. com. They have a great forum, you'll get a few responses. This forum isn't very user friendly-agreeing with KC. Good luck with your search. Be patient, you'll find your bike!

Thanks for the advice, KAR. I've seen some of the research on tri-bike efficiency and it certainly seems to be worth the investment... when I'm able to make it. I still may need to put off the purchase until I'm out of grad school and have a steady income again. I might even appreciate the tri bike a little more having struggled through on a road bike, right? I saw a flier for a local tri-club just the other day, so I will take your advice and join and see what those guys are riding (or might be done riding).

As for my plans to do a "few" iron distance races next year... Well, I'm the kind of guy who likes to dive into the deep end. I've learned my lesson about overuse injuries the hard way, and I'm very methodical about my preparation now. But I will take your advice and be extra vigilant. Thanks, again!

To be honest, the difference in aerodynamics is probably not huge if you can get into a comfortable position on your road bike. The bike frame is only about 10-15% of your total drag, so improving the drag of the bike frame is only a few percent of your total drag...at best. I saw a comparison recently with identical positioning, the aero bike was only worth about 0.5mph (at 22.5mph avg speed) so the real questions are:

What wheels do you have? A decent set of semi-deep front and aero disc cover in the back is worth about 1-1.5mph on my bike.
What helmet are you using? A good aero helmet is worth more than a pair of top end Hed or Zipp wheels...I race in an LG Rocket Air, but even a Chrono was 10W better at 20mph than my old Giro Eclipse.
What tires are you using? A low drag set pumped up to 115-120psi (depending on body weight) can be easily 0.5mph faster than a high drag set. There's a useful chart over at www.biketechreview.com of trainer tests of various tires. I race on Bontrager Race X Lite Pros, but the Vittoria Open Corsa EVO CX is also very good.
How is your position? Are you upright and forced there because of the frame geometry, or can you get reasonably low in the front without making your bike unstable? A longer stem can sometimes help with stability, making the bike less twitchy.

In general if you can get into a comfortable, stable aero position on your current road frame...don't bother switching frames. Or do what I did and get a BP Stealth frame (I paid $900 for frame + fork but that was 5 years ago) and transfer over all your parts. Either way the position of your body is key to everything.