Originally Posted by
DaveSSS
As already noted, just your height is not enough information. Cycling inseam is more relevant.
Most likely though, a 54cm will be the proper size. Note that there is a big difference in the head tube length between the 6 series and the 5 series. The 5 series has a 30mm taller head tube for the more recreationally inclined rider and the 6 series is for those who want a more aggressive position.
I'm a half inch short of 5'-7" tall, but I have long legs with an 83cm cycling inseam and 73 cm saddle height. With my short torso, I'd have to go with the 52cm 6 series. I could use an 84 degree stem and no spacers to get the 11-12cm saddle to bar drop I use. Most people would choose the 54cm, but the reach is on the long side. The 52cm 5 series is another option with 20mm more head tube length and only about 5mm less reach.
Having half a foot of saddle to handlebar drop isn't necessary. Nothing says you can't get a shorter stem. I'm 5'10" and ride a 58cm 5.2 Madone. I chose this size because I have a long inseam and didn't want a skyjacker seat post. I'm fine with a 90mm or 100mm stem. I've been fit on a Retul and that's where I'm according to that as well.