Those key development stages in full 😉
Started in a seat tube mounted bike seat at about six months.
(EDIT: Actually I started with a Baby Bjorn on the front and rode to nursery at three months)
Kiddyback tandem at 3.5 yrs/six months with crank shorteners, extra small saddle, adjustable bars and Rhode Gear Limo (no seatpost, see)
London to Oxford at 6 yrs on tandem.
Burley Piccolo plus Kiddyback Triplet at 7/4 yrs (Now THAT was hard work!)
Separate bike for longer road rides with tandem at same age.
KMX recumbent at 7 yrs
Variety of MTB and Road bikes that ever expands.
Kids get bored easily – always have a good reason to ride. At first it was out to see the cows in the farm once Teen1 woke up (Usually at about 5 am). Trips to ice cream, journeys to nursery/shops. For them cycling is often a means to something else.
Oh, and kids need one CHOCOLATE BOURBON every three miles. It’s the rules! These are my top tip and give a nice taste without the mess. I used to keep them in a saddlepack for the stoker (who also had the bike computer, bell, horn and all signalling duties)