My height is 5` 7" and my inseam is 32cm. 56cm bike is too tall for me? I ride 56cm road bike now. I have put the seat in 72cm i have the stem all the way down. The bike with that setup seat height and low stem is feel too big. I have to lower little the seat and raise the stem little or i need smaller frame 54cm? or maybe 55cm.

An uploaded picture would be much easier to diagnose.

I'm 5'7" with a 30" inch inseam. I ride a 54 cm gravel road/adventure bike, which is the spot on size for me. You're better off with a 54 or in an odd size, a 55.

If you're considering a road bike with a long top tube, like a Lemond, you need to go down one size to a 53.

I try take tommorow picture and post here. One road bike i have is lemond is 57cm looks i buy the wrong size bikes?

Way too big! I was on a 55 cm Lemond and I felt stretched out even with adjustments. I should have gone with a 53 cm due to the long top tube. Sometimes do you have to go smaller from your usual size.

The length of the top tube is probably more important than the seat tube. If you can get the saddle low enough for your height, then you don't need to worry about frame size for saddle height reasons. Then you might have too much distance from the saddle to the handlebars. If you have a longer reach stem (more than 90mm), you could get a shorter one which could bring the handlebars closer. If your stem is already pretty short and you find the reach too the handlebars too long, you could try out some smaller bikes and see how they feel.

And yes, if you are looking at a starting point for frame size, I would start at 54 or smaller.

where is affect big frame size other than feel big and stretched is affect in pedal power? All my bikes ihave buy used and before i not give attention in frane sizes much but now i look in that

I have a 56 road bike & I'm 5'9".. **

but the style in the races has changed .. tall seatposts low bars, in the Peloton of late ..

I don't race, never did, so I fit my road bike differently , saddle and bars about same height..

** and 68, by now.. lost an inch . was 5'10"

when the big not fit is too big for the rider is can affect the max speed and the average speed?

When the size is correct, the bike fits you like a glove and your leg extension feels more natural and you can ride faster with more confidence.

And there is the added safety factor of being able to dismount without endangering your family jewels.

No, the work the rider puts out is what determines how fast they go.

The above recommendations are spot on, 53-54cm frame is what I would recommend, perhaps even a 52, depending on your body proportions.

I'm 5'11" and most of my road bikes are 57cm C to C and I would consider this to be at the limit. My next bike will probably be in the 55-56 range but this will depend mostly on the TT length.

I'm 5ft8 and my bike is 50cm. You should look for a 50-52cm bike . I had a 56cm before and it caused me a lot of pains