The Trets from Hase is great for helping kids with special needs be more independent – it’s very stable and safe for independent riding, but it can also be hitched to the back of a parent’s bike for riding on roads or for longer trips. there are loads of options available if needed, from special pedals and handlebars to a jogger kit so an adult can push while running behind.
For all the options, have a look at the Configurator on Hase’s site.