Dreaming of a motorbike that you own but have not ridden, which is then crashed by others and your younger sister, can have several interpretations.

1. Ownership and Control: The motorbike often symbolizes freedom, adventure, and control over one's life. Since you own it but haven’t ridden it, this could suggest that you have opportunities for adventure or personal growth that you have yet to explore. The crash might represent fears about losing control or feeling like those opportunities are being threatened by external factors.
2. Family Dynamics: Your younger sister's involvement in the crash may indicate concerns about family relationships or dynamics. Perhaps you feel protective of her or fear that her actions might affect your own stability and sense of freedom.
3. Unexpected Events: The crash itself could symbolize unexpected events in your life that are outside of your control. This might reflect anxieties about unpredictable changes or disruptions, especially related to family or close relationships.
4. Missed Opportunities: The fact that you haven’t ridden the bike could indicate feelings of regret or missed opportunities. The crash involving your sister and others might highlight anxieties about not being able to pursue your desires due to external circumstances or family responsibilities.

Consider reflecting on your current life situation and any relationships that may be contributing to these feelings. It might be a good time to assess your desires for freedom and adventure and how they align with your responsibilities to others.