My height is 5` 7" my inseam is 32" online carculator show me i need 55cm bike. I have two road bikes. one is 56 cm the other is 58 cm. Also i have one cannondale frame is 61cm i want to build see how is ride, that 56cm and 58cm is close to my size? the 56cm have top tube 55cm the 58cm have top tube 56cm which bike is closer to my size. And how i found what really bike size fit me.

Your question isn't clear, probably a language barrier, but anyway the 61 cm Cannondale is likely to be much too big. Just put the wheels from your other bike into the Cannondale frame and stand over it, if you can, and see for yourself.

you measure the BB center to the top of the seat tube.. that is what companies call frame size.

go to shops test ride bikes.. Now go back to work ..

the boss can find the web places you go to on company time you know ..

His question is clear to me. He wants to know which top tube length (55cm or 56cm) is better for him. We can't know that of course, because we don't know anything about him besides his height and inseam. I don't worry about details like that myself. I just buy a stem that will get me the position I want on the bike. The 61cm is too big if the o.p. can't stand over it. If he can, all bets are off. I wonder what Google translate will do with "all bets are off". I really need to get the camera out and photograph my stable, so once and for all we can put this myth to rest that it is necessary to select frames using fit calculators, slide rules and spare computer time from Jet Propulsion Laboratory in California.

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Thank you for your answer. that bike size carculator is myth really? I used ride 63cm steel bike. Is was too tall for me the top tube but other than that i had ride that bike for two years. That stem size how i can select that. My steel bike have the old quil stem. i want put newer stem on that bike. Is possible fit that new stem. I have seen stems in local community bike shop i go some times. But i not know how to install that stem i not see the adaptor in that place.

Thank you for your answers

I ride from 52 to 55. Being 5'7" - the right fit can vary with the brand, the geometry and the bike.

I not know if is correct but online bike size carculator tell me i need 55 cm bike. closer to my inseam is size i see bike 56cm. My bike i have now is 56cm from the center of the bottom bracket to the seat post. In the size give me the online carculator that 56cm means the top tube i need is 56cm too?

The calculator is a good starting point, but there's no reason to fret over 1cm. Does your 56cm feel good? That's the only thing that matters here!

Yes the 56cm feels good. But the 58 cm bike i have is feels good too. I used to ride for two years almost daily steel 63cm road bike. In hilly trail from 700 feet to 900 feet elevation 10 miles long i do that ride in around 50 minutes. When i had the lighther bike the 58cm i think i do that 10 miles faster but other i felt in hills i ride some faster in overall time i not see any improvement in my time really. What is means really when say the bike fit the person and what happens when the bike is too tall for the person