The objective of this research report is to support the development of the forthcoming Cycle Safety Action Plan being prepared by Transport for London to be published in 2014. TfL wished to improve the understanding of the factors which lead to collisions involving fatally injured cyclists and those with life-changing injuries. The research focussed on an in-depth analysis of collisions that occurred between 2007 – 2011 when there were 79 fatal and life threatening collisions involving cyclists of which 53 were available for analysis.