Triathlon - Tri or road bike?

Note sure if this debate has raged here before or not but (maybe it isn't a debate).....why do we need tri bike for triathlon vs. road bike....I find road bike easier to ride especially in hilly, twisty areas where I ride (Bay Area/Tahoe)....I am training for triathlon but on my road bike.....the usal comments I hear is that the the tri bike is designed for flat, straight racing and that the tri bike geometry favors muscle groups needed for other sports notably running....I find the transition from bike to run tough no matter what the bike ;-) Look forward to your comments.....I am pretty new to tri, my strength if I have one is running....

see my comments here:
http://www.bikeforums.net/showthread.php?t=77428

Thanks, those are good comments......sounds like you have to be a good bit along on the performance curve before the differences start to register....

The tri bikes have a more forward seat position compared to the pedals. The seat tube is straighter up than a road bike. They say this is to ease the transition from running to riding. It's not bent over as far as a road bike, it's a little closer to straight up.

why do we need tri bike for triathlon vs. road bike

You don't have to have a tri specific bike to do triathlons (which sounds kind of funny coming from somone who just bought a tri specific bike). Since you're getting into traithlons your current equipment is just fine. Add a set of aerobars and get used to riding with them and do your first triathlon. In my case I just bought a tri specific bike becuase I will be concentrating on triathlons for at least the next two years. My focus is on longer distance (1/2 IM and IM distances) so a tri specific bike made sense. That and it was just so damn beautiful I had to have it :)

You don't have to have a tri specific bike to do triathlons (which sounds kind of funny coming from somone who just bought a tri specific bike). Since you're getting into traithlons your current equipment is just fine. Add a set of aerobars and get used to riding with them and do your first triathlon. In my case I just bought a tri specific bike becuase I will be concentrating on triathlons for at least the next two years. My focus is on longer distance (1/2 IM and IM distances) so a tri specific bike made sense. That and it was just so damn beautiful I had to have it :)

This is very true.
I would also add, that I rode a tri bike for many years as a road bike.

you could also get a profile seat post which will put you over the pedals... it is cheaper than a tri-bike

you could also get a profile seat post which will put you over the pedals... it is cheaper than a tri-bike

Being over the pedals is just part of a good bike fit - I'm over the pedals on every bike I own. Depending on the bike geometry and your normal position on it - will dictate the amount of "offset" in a seat post that will be need specific for you. This is where good bike fit technicians start - from there they can work on your body position which involve bar height and reach. I don't understand how a "profile seat post" does that any better than any other brand. If you postion yourself too far forward it places you at risk of not being in the most optmized positon. I just don't see the logic of throwing parts on a bike at random - they come out of "need" from a fit analysis. After you know what you need based on a fit analysis - you can then pick and choose which parts are available to suit your need for a given purpose or type of racing you intend to do.

That purpose can change (and in turn change you bike set-up) depending on if you just do TT's (and not run after), do a short Olympic distance event or an Ironman Triathlon.