I have spent some time searching for this answer (perhaps there isnt one) and not sure what to do.
I just got back into riding last year on my 14 year old Rockhopper Comp (21.5"). I put Fatboy slicks on it and tried to get it as efficient as possible. It has both a hard front and tail. I kept looking at the road bikes last year thinking that is what I really needed/wanted, as they would be better for the longer haul. Longest ride last year was 40 miles and it killed my wrist.
So, I go to my favorite LBS yesterday and start looking at bikes. They had a closeout Roubaix in a 56CM. It just looked small to me, no idea why. I am looking to spend about $1500 on the bike.
We put the 56 on the trainer and it felt small. When I got out of the saddle (on the hoods) I felt like I was out way to far over the front wheel. Remember, this is my first road bike. I had about 4-6" on the standover. I liked the bike, but it felt "small". Again I don't know much about this.
Then we put a 58CM Tarmac on the stand. The Roubaix and Tarmac have the same top tube lengths in the same frame size, but the Tarmac has a bit longer seat tube (35CM longer than the 56 Roubaix). I had about 1-2" of standover. First glance on the trainer it felt more comfortable, but that is only for like 5 minutes.
After all this was over, I decided on a Sectuer Comp in 58.
But, here is what keeps playing over and over in my head. Is the 58 too big? The 58 Sectuer has the same geometry as the 58 Roubaix except the seat tube is 535 v. 540 (550 on the Tarmac). I am thinking that shorter seat tube will give me a bit more standover. How do I get the proper size? The guy at the shop thought initially the 56 would work, but thought the 58 looked better. I don't know anything about sizing. I am just worried that the 58 will be too big and then I am "stuck".
Also, I may just be lusting after that closeout Roubaix.
I am 6'1" with a 32.5 inseam (longer torso).