There has been limited development of advanced rider assistance systems and on-bike information systems for powered two-wheelers (PTWs), even though research suggests that population-wide deployment of assistive systems could significantly reduce PTW crashes. This study aims to understand general and system-specific factors that are likely to influence acceptability of PTW assistive systems, including barriers that may prevent uptake and proper use of systems, through a large-scale survey of European riders. The survey was available in seven languages and attracted 6297 respondents. Respondents were frequent riders, who rode primarily for leisure purposes and had high awareness of assistive systems. Cluster analysis revealed two groups based on overall acceptability of assistive systems. The moderate and low acceptance clusters differed in terms of riding practices, risk perception, attitudes towards rule breaking, and some personality traits. Overall acceptability was low, but riders who perceive greater risk in riding display higher acceptability. Acceptability was highest for systems that do not interfere with the riding task, are well-known and/or considered reliable (e.g., night vision, ABS, eCall, advanced front-lighting system). In general, riders believe that existing safety equipment (e.g., helmets, protective clothing) is more reliable, provides greater resistance, and is considerably cheaper than more sophisticated assistive technology. Riders believe that innovations should focus on protective equipment, since they believe crash prevention is better addressed through rider training. Finally, riders felt there should be more emphasis on vehicle tyre condition, while tyre pressure control systems were identified as potentially helpful.