Context. The propagation of interplanetary coronal mass ejections (ICMEs) and the forecast of their arrival on Earth is one of the
central issues of space weather studies.
Aims. We investigate to which degree various ICME parameters (mass, size, take-off speed) and the ambient solar-wind parameters (density
and velocity) affect the ICME Sun-Earth transit time.
Methods. We study solutions of a drag-based equation of motion by systematically varying the input parameters. The analysis is focused on ICME
transit times and 1 AU velocities.
Results. The model results reveal that wide ICMEs of low masses adjust to the solar-wind speed already close to the sun, so the transit time is
determined primarily by the solar-wind speed. The shortest transit times and accordingly the highest 1 AU velocities are related to
narrow and massive ICMEs (i.e. high-density eruptions) propagating in high-speed solar wind streams. We apply the model to the
Sun-Earth event associated with the CME of 25 July 2004 and compare the results with the outcome of the numerical MHD modeling
