Failure Analysis of Motorcycle Chain and Axle


An accident involving a motorcycle with a driver and passenger occurred on an interstate.  The motorcycle lost control and according to the police report, the motorcycle had a chain or rear axle failure causing the driver to lose control.  

Services Provided

Rimkus Consulting Group, Inc. was retained to reconstruct the accident and determine why the axle and chain broke on the motorcycle.  Rimkus also was requested to review the design of the chain and rear axle assembly.

During the course of our investigation, Rimkus Consulting Group reviewed the police accident report, participated in a joint inspection of the motorcycle, reviewed numerous depositions related to the accident, and performed a failure analysis of the rear axle.  A finite element analysis was also conducted on the motorcycle’s rear axle.  Based on our analysis, we concluded that:

  • The motorcycle was traveling between 65 to 73 miles per hour when it began to lose control.
  • Based on the finite element analysis and inspection, there were no design defects with the axle system design that caused or contributed to the loss of control and accident.
  • The chain came off the rear sprocket and became jammed on the rear axle resulting in the rear tire locking and the motorcycle began to slide.
  • As the motorcycle slid, the rear axle broke.
  • If the axle had failed first, only application of the brakes could have locked up the rear tire.  There was no testimony that supported that the brakes were applied.

National Practice Leaders

Dirk E. Smith

Ph.D., P.E., ACTAR

Senior Vice President, Forensic Division