Road bike recommendations

YES! - and therefore the the set back on the seat post is different on every picture to cancel out the effect of a different ST angle <== this

I guess I need to spell it out... People often say that Surly Steamrollers are low and long. Let's calculate reach and stack for size "59":

REAL:
STACK = 70mm + (375mm + 163mm) * sin(74) = 587.2mm
REACH = 587mm – STACK / tan(73) = 407.5mm

Now let's only change seat tube angle (from 73 -> 72 degrees) and see if that affects reach:

IMAGINARY:
STACK = 70mm + (375mm + 163mm) * sin(74) = 587.2mm
REACH = 587mm – STACK / tan(72) = 396.2mm

We see that one degree change in the seat tube angle is pretty close to 1cm change in reach when we don't change the effective top tube length as well. In this case reach is less, because more of the top tube is behind the bottom bracket. This is pretty well know fact and many bike fitters use it as a rough guideline.

Usually one wants to achieve the same fit triangle between different frames if the intended end use for the bikes is the same. In the example above, let's imagine that the saddle and handle bar are at the same level to make calculation more simple. To achieve the same fit triangle between the two Steamrollers above (real and imaginary) one would position the saddle to the same position in relation to bottom bracket (height and setback). We can use 80mm setback as an example. Then we would like to maintain the reach from the saddle nose to the center of the bars equal as well. Let's say that 600mm would fit the rider. To achieve this we would need different length stems for real and imaginary Steamrollers to compensate the difference in reach:

REAL: 600mm – 407.5 – 80mm = 112,5mm (roughly 110mm stem)
IMAGINARY: 600mm – 396.2 – 80mm = 123,8mm (roughly 120mm stem)

Seat tube angle clearly affects reach and one can easily see this from the formula. Seat tube angle is one of the variables ffs. Thuekr we are probably talking about the same thing but from different perspectives. However, if you claim that seat tube angle doesn't affect reach you are wrong. If the difference in reach between the two Steamrollers would be cancelled out by just using inline or offset seat post then we wouldn't need to change the stem length, right? But this is not the case because we want to achieve the same saddle setback and to achieve the same setback we (might) need different seat posts. To maintain the same saddle to bar reach we still need to compensate the change in reach with different length stem as well.

But you don't have to believe me, you can wait for some like mdcc_tester to come here and give he's input.

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#nothelping

Nice attitude, read the previous posts as well. There is plenty of help there. Maybe I should return the favor ;)