There are two main types of brakes found on children’s bikes: coaster brakes and hand brakes, although some bikes have both. Part of this is regulatory and beyond the control of manufacturers; they may have to spec a coaster brake because there are legacy laws governing how bikes are sold.
Coaster brakes work by pedaling backward. Lots of bikes for younger children have them.
Hand brakes operate via a lever attached to the handlebar, and most bikes for children only brake the rear wheel. There are two types of hand brakes as well. Disc brakes tend to have more power and are a bit more expensive, and work better in all kinds of weather; rim brakes clamp against the wheel’s rim and may be less potent, though frequently offer at least the same level of modulation as a disc brake.
If your child bike has lever-actuated brakes, those levers most likely have a reach adjustment. This brings the lever closer to the handlebar, so it’s easier for smaller hands to grab, which is critical for safety. If the bike you purchased doesn’t have this adjustment, a bike shop can swap out the levers for adjustable ones.
As with brakes, your child needs to be able to easily operate their shifters. Avery at Cannondale said bike makers are increasingly building bikes with low-effort shifters, meaning the mechanism isn’t as stiff as in adult bikes. Raul Atencio, the retail manager at Universal Cycles in Portland, Ore., Says you want to hold a bike statically and watch to see if your child can easily operate the brake levers and shifters. Again, the local shop should make this evaluation. Know that, like brake reach adjustment, shifters can also be repositioned for better leverage for your kid to use.