This paper by Arunachalam et al., (2019) gives a fair insight regarding the effectiveness of various tools and techniques used for posture evaluation and various research gaps pertaining to the user-centered design of motorcycles to improve riding posture.

This second paper by Amrutkar & Rajhans (2011) aims at finding the problems associated with motorcycle riding posture.

Reference:
Arunachalam, M., Mondal, C., Singh, G. and Karmakar, S. (2019),“Motorcycle riding posture: a review”,Measurement, Vol. 134, February, pp. 390-399.
Amrutkar, A. S. and Rajhans, N. R. (2011). Ergonomic posture for motorcycle riding. April Conference Paper