Stem measurement question

[The Londoner]

If a road bike stem is quoted as being 90mm, is that from end to end, or centre to centre?

[fixedwheelnut]

Usually centre to centre,
as a rough guide once your saddle is in the right place [knee joint over pedal spindle at three o clock position] with your elbow on the saddle nose held flat towards the bars with fingers pointed and other hand at right angle to finger tips, the little finger should be in line with the centre of the bars.

[The Londoner]

fixedwheelnut said:

Usually centre to centre,
as a rough guide once your saddle is in the right place [knee joint over pedal spindle at three o clock position] with your elbow on the saddle nose held flat towards the bars with fingers pointed and other hand at right angle to finger tips, the little finger should be in line with the centre of the bars.

Thanks, that makes perfect sense.