Originally Posted by
JAJ0404
Thanks for the comments, my current frame is 54CM with 172.5 cranks. The size feels good, but maybe, if anything, slightly too big, so for years I thought maybe my next bike would be a 52CM. But lately I've been thinking that the bigger frame keeps the top of the head tube higher, giving me a LESS aero position, which is what I want. I definitely want the endurance positioning. My fit isn't giving me any pain, but I'm wondering if there's something else it's costing me, like less power? Or something. Just noodling for some ideas to check.
You can't go by the height of the top tube. You need to learn to look at the stack height in the specs. Otherwise you might find you have too much reach from saddle to bar and are still in that more aero position than you might want.
Todays Roubaix has one of the highest stack heights of bikes out there today. I didn't search hard for the geometry of a 2004 Roubaix you have currently so I don't know how it compares. If you go to a shop then just tell them you want a road bike with a relaxed fit. Sizing varies between one model of bike to the next, so don't just assume that a 54 in one model is the same as a 54 in another model bike. And from my experience with different sizes, you can usually ride a bike a size up or down from ideal. Just might have to change up more stuff like stem length.