Best thing is to get a real balance bike, you can buy them cheap now,,most Walmarts have them for somehwere around 50 bucks.
We had my grandson riding a 2 wheeler by three. You want them to use the balance bike only as long as it takes them to get good at it,,then move them to a 2 wheeler pedal bike.
How we did it was,,,as he was learning the balance bike we also had a 2 wheeler with training wheels just so he could learn how to use the brake. As soon as he learned the brake and the balance bike, we moved him on to a 2 wheeler without the training wheels. By the time he was 4 he was riding his bike 8 miles at a time. He is 6 now, he rides a 6 speed mountain bike with 20 inch wheels with hand brakes and a BMX type bike.
My grandson was very motivated cause I ride a lot and he wanted to be able to ride with me to the store and playground. Not every kid is going to learn to ride a 2 wheeler at 3.