For younger kids, there is the the Trek Trikester, an amazingly robust little tricycle with front wheel drive

For older children, the bigger bikes are real bikes, not toys, built with the same attention to detail and safety as our grown-up bikes. They are made to last, and can be passed on from child to child.

Trek’s range from the 16" wheel Jet and Mystic 16, single speed fun bikes, through to the 220, which, with 21 speeds, v-brakes with small levers for small hands, cranks that are drilled for two leg lengths, so that they grow with the child and a suspension fork is a proper small mountain bike.

Marin also do children's bikes, with the emphasis on lightness, strength and rideability.
Available in 20" and 24" wheels, they are designed for the child with wider horizons.