Can anyone suggest a charity we can donate a child's bike to?

Our little boy has outgrown his bike and is getting a new one for christmas, we want his old one which is still in great condition to go to a child who may not be lucky enough to have their own, or a children's home or somewhere where it would be loved and used. Don't want to put it on freecycle or anywhere at risk of carbooters etc. If anyone can suggest any one we can contact that would be fab!! We're near Southampton in Hampshire!