frame size.
 

I see online bike size for me with the horizontal top tube is 56cm. I do my inseam cm . Is 82cm x 0.69 is give me 56cm bike. say for bikes with the horizontal top tube. the for semi compact frames i do 82cm x 0.64 is give me 52.48 fdrame size. LBS tell me i need 54 cm. What is the correct size for semi compact.

Your horizontal (or virtual) top tube length should be derived from your torso and arm length and riding posture, so I can't understand why a fit calculator should prescribe this using your leg length. And horizontal top tube length should be the same whether you're riding a traditional, compact, or semi-compact frame. It's a virtual dimension, meaning it corresponds to no single component of the frame. So if 56 is your horizontal top tube, select whatever nominal size matches this.

Generally, 56 cm horizontal top tubes are found on bikes whose nominal size is 54-56 cm. In most brands, that's considered medium to large. This would be an appropriate size for riders with average proportions who are taller than 5'8" but shorter than 6'.

I'd say a... 59

What is your overall height?

i am sorry for my late answer. Now i see your question. My height is 5' 7" and my in seam is 32"

I am about the same size and ride a 56CM. But I must add that I got a pro fit. 100 mi rides and some mountain climbing with relative comfort. Little over 4,500 miles with the 56 and still happy.

I have used bikes never i have do pro fit. is worth i do that? Is long time i not have ride i am so bussy. But i used i do 20 miles every day in bike trail with elevation from 700 feet to 900 feet. How long time is take you do the 100 miles. Never i have do that but i want do that this spring. What bike do you have.

I recommend 54. To those who'd recommend larger, I'd say, look at a large 54 like Specialized or Scott.

one LBS have tgell me if i do the fit is put me in 54cm bike. Now my bikes all i have buy used is 56cm 57cm and 58cm. what is the cons in that sizes vs the 54cm. or what pros i go have in 54cm. One man tell me few months ago is go from 56cm to 54cm and is was much faster with the 54cm bike.

54cm compact frame is same as the 56cm or 58cm older bikes with horizontal top tube? or slope geometry bikes?