A variation of the clock paradox and a distinguishing feature of an   inertial frame
  The clock paradox is analyzed for the case when the onward and return trips cover the same <<distance>> (as observed by the traveling twin) but at unequal velocities. In this case the stationary twin observes the distances covered by her sister during the onward and return trips to be different. The analysis is presented using formulations of special relativity and the only requirement for consistency is that all observations are made from any one chosen inertial frame. The analysis suggests that a defining feature of an inertial frame should be based on the continued maintenance of the distinctive synchronicity of the clocks co-moving with it. Published in Journal of Physical and Natural Sciences Volume 1, Issue 1, 2007 http://www.scientificjournals.org/journals2007/articles/1102.pdf 
Chandru Iyer, G.M. Prabhu