Kids 'n Bikes
I started all of my kids on Strider walking bikes before the age of 1.
My daughter picked it up faster than my son, but that may be because she grew up in a house with carpets and super soft padding below the carpet. She could fall and not get hurt. By the time both were 1 1/2 they were riding their Strider's outside on the road like pro's.
Once my daughter turned three, I moved her to a pedal style Strider bike. The relevant features are:
1. Low stand over height
2. Cranks with Pedals!
3. 12" Foam wheels ( no flats )
4. Super light.
I took a bike which looked like the blue bike above and removed the training wheels, water bottle cage, and chainring cover to lighten it up. I held my daughter's shirt while she got comfortable getting started with the pedals. Then she was gone....no need for daddy anymore.
Next I bought a 16" princess bike ( super heavy ) from a department store, but my daughter never used it. She went from the 12" wheel bike to a 20" BMX style micro mini which weighted about 15lbs. Then she moved to a Downtube Race mountain bike.