When people speak of bicycle frame sizes, they generally speak in terms of the seat tube length.

人们谈到车架尺寸时，通常是按照立管尺寸来计算的。

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The length of your seat tube is going to help you and the length of your top tube and even the Angle of the three main tubes all put together is going to help you, but color is not.

您的座位管长度会帮助您和您的上管的长度，甚至所有的三个放在一起，是要帮助你主要管的角度，但颜色不是。

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Some bikes with slanting top tubes are measured as if there were a level top tube, they use the length that the seat tube would be if it was as high as the head tube.

而有些上管倾斜的车架， 会被当作水平上管的车架来测量。 立管长度就会从中轴中心量到立管上与头管一样高的位置。

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