I would definitely recommend a balance bike: no pedals or gear system. The kid learns how to balance and then you upgrade to a bike with pedals and away they go! We purchased a "Specialized" bike from our local bike shop and it is awesome. My then 2-yr old really got the hang of it just as he turned 3. He could fly on that thing! Also, the good ones are extremely lightweight so they are much easier to balance and get up and down hills. My son was able to ride a "real" bike without training wheels 3 months before his 4th birthday. This has been great because I'm able to help my 2-yr old on his balance bike while the 5 year old cruises on his own. They are expensive, but you can resell them or even get a credit towards your next bike when you buy from a local store. Good luck!