hello everybody!
after some time it is finally time to change my trustworthy klein quantum road bike.i am looking to buy something through ebay since prices in Greece are insanely high.
Anyway,i think i have concluded in the giant tcr composite frameset on which i will install a dura ace/ultegra mix.The point is that although i have found some new frames on the internet i do not now what frame size to get.My klein is size 54 but as far as i know the giant frames have a sloping geometry which makes it hard to get a the exact size as my klein.i am 1.80m tall and weigh 82kg(do u think i will have any problems with a composite frameset?)...what size do u guys recommend me? the medium or the large size?
thanks in advance for ur help.
max

What is your inside leg ?

I am 5'11" and use a medium.

my inside leg...
its 81cm.

you are most likely a medium unless you have a very long torso. I ride a 56 with a 56.5cm top tube and I am about halfway between a medium and a large on the giant TCRs. If i were getting one i would get a medium and a 12 or 13cm stem

I have an 83.8cm inseam and I am 180cm tall.

The large will be too large for you and the medium is at risk of being too small. Nothing that can't be fixed with the correct stem length. However, the head tube of the medium is also considerably shorter. Depending on the seat to handle bar drop you might require an excessive amount of headset spacers.