http://www.islabikes.co.uk/
We have an Isla Bike Balance Bike which our 2 daughters both used and went straight on to riding an Isla Bike with pedals and no stabilisers. One of our daughters was riding the pedal bike by the time she was 3..... all down to the balance bike (and wanting to be able to do what her older sister was doing).
I don't know much about bikes but I can't recommend Isla Bikes highly enough. Check out the website to get all the technical info on why/how they work and what age and height is recommended to start using them. My brother works in the mountain bike industry and says they are the business.
We own 3 so far and plan to get the next size up when we need it.