We should set a good example for safety and get that poor cyclist a helmet. Brains are neat, keep them off the street.
I assume you're talking about the EmojiOne font we bundle for use on XP/Linux, as looking at http://emojipedia.org/bicyclist/ the Emoji that come with Windows and OS X already have a helmet. Proper safety is observed by all vendors for http://emojipedia.org/mountain-bicyclist/ (except HTC, but the rider's head is clearly detached and so it's already too late.) You'll need to report an issue to the EmojiOne project: https://github.com/Ranks/emojione If you instead want a combining character for use with other non-helmeted emojipeeps, you'll need to propose that to the Unicode Consortium.