tri bars on road bikes

if I understand the geometry correctly a road bike with tri bars clipped on, causes a change in the hip angle to a less advantageous position because the top tube length is longer than a tri bike and the seat post angle is less but can I compensate for this by using the look ergo 2 seat post with variable seat angles and sliding the seat forwards does this work ?
I was hoping to use this set up for 1/2 ironman distance
http://www.chumster.co.uk/forum/imag...n_question.gif

Yes, you understand correctly. If the seat post you're using now has some set-back, you can probably get into the right position just by turning it around backwards.

I may be wrong but isn´t it that the bars are lower , with regards to yuor shoulders , that´s affecting the torso/hip to thigh angle ?
having spent time setting up your saddle height and position over the pedals why mess that up simply because your leaning forward more than normal ?
surely it´s like riding on the drops - you just have to get used to it ?

__________________
' too old to rock 'n' roll : too young to die '

That's exactly the point. Your TT/Tri position shouldn't really be any different than the way you ride normally. Think about it as rotating your entire body about the bb spindle to get your torso more or less horizontal.

yes but how does moving your saddle do that ? it´s just a case of your body learning to work in a ( slightly ) different posture : nothing radical , it just needs time on the cycletrainer .

__________________
' too old to rock 'n' roll : too young to die '

Try sketching it out. If the bars move down and/or forward, then moving the seat forward keeps all of your relative angles the same. This is exaclty why tt and try specific frames have steeper seat tubes than standard road bikes.
It is possible to adjust to a different position through training, but it's not always desirable. If you're doing road and tt racing, then you end up having to train your legs to two different positions with the end result not being entirely optimal for either. In the triathlon case, you want to be careful to not use too many of the same muscles for the bike and run portions.

the steeper angle is more todo with cadence than posture : that said if you want a tt bike then best buy one , along with disc wheels etc because its , as you a say a different beast and will need to be aclimatised to .

__________________
' too old to rock 'n' roll : too young to die '