It is easiest to fit a bicycle to a child if it is adjustable. An angle adjustable stem, rise handlebars, and a saddle with super long rails should give parents the adjustability to make a bike fit for many years. Children are normally very flexible. There use plenty of body positions, so short or long stems will work with most kids.
I strongly suggest you make sure there are no problems with the seating position.
Dangerous seating positions:
1. If the knee is completely straight when pedaling this could cause a meniscus tear in the knee
2. If there is an over exaggerated knee bend this is bad for the joints
3. If the child is leaning too far forward to hold the handlebar this will force the rider to sit on soft tissue instead of bones which will cause pain behind their private parts
Proper seating positions:
1. The child should sit on the bike in a relaxed posture. They must be sitting on their bones at the back of their rear end to avoid soft tissue pain. If they are leaning too far forward you will need to move the handlebars back. This can be done by rotating the rise bars or bringing the angle adjustable stem towards the back of the bike.
2. The child’s wrists should be straight when engaging the brake levers. If they are not you need to rotate the levers until they are.
3. When the crank is at the furthest point from their hip, they should have a slight knee bend. If that is the case it will be hard for them to pedal. Make sure their knee is never straight because if it locks out while biking it could cause an injury. Lifting the saddle will avoid this and make it easier to pedal.
4. Make sure the ball of your child’s foot is in the middle of the pedal. If it is not, you should move the saddle forward or backward as necessary to accomplish this.
Once the bike is adjusted their power transfer will increase making riding easier and more fun. Additionally, the bike will fit better, hence making it more comfortable.
©2018 Dr. Yan Lyansky