Hey, when I published an article about Sinister Industries and its PPO/PA plastic material 4″ extended saddlebags, some wondered about the material used on their own stock and after-market motorcycle bags, and others in the industry producing fiberglass bags were not to happy that I ‘advertised” PPO/PA plastic.
First let me mention again that Harley-Davidson abandoned fiberglass about 5 years ago and that all their saddlebags are now made out of PPO/PA. So, for those who want to know more and compare (I had to receive a full briefing). Advantages of PPO Plastic include: High strength, High heat distortion resistance, Outstanding hydrolytic stability, Good creep resistance, Resistance to stress cracking, Resistance to weathering, Excellent chemical resistance, No body work needed, Super light weight, Inside lining not required. Disadvantages of Fiberglass include: Heavy, Stress cracks over time, Inconsistent thickness, Air bubbles, Requires body work, Inside needs to be lined. (yes, picture is my own Harley Road King…still with fiberglass bags)