Contributing factors to motorcycle injury crashes in Victoria, Australia

•We investigated the interaction between rider, other road user and environment factors in multi-vehicle crashes.•Increasing rider age and lower traffic density were both associated with human error by the other road user (vs. rider).•A secondary road design issue was associated with rider error (vs. other road user error) as the primary contributor.•Inappropriate rider speed was associated with other forms of rider error (vs. other road user) in multi-vehicle crashes.•For single-vehicle crashes, the road environment was judged as a secondary contributor in over three quarters of crashes.