Is it obligatory to denounce all widespread reprehensible acts in the streets of Muslim Egypt by word or by leaflet, if possible, despite the fear of committing something unlawful after denouncing, and is it obligatory to denounce while riding a bicycle?

Enjoining what is right and forbidding what is wrong is one of the fundamental principles of religion and an obligatory duty by consensus. It is to be done by changing it with one's hand; if unable, then with one's tongue; and if unable, then with one's heart, and that is the weakest of faith. This is conditional upon ability, so whoever fears harm should condemn it in their heart. The presence of a wrongdoer does not nullify the obligation of condemnation upon others.