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Kids' Bike Fit Guide

Finding the correct size bike for kids is essential to ensure the most fun, skill progression, and safety. When kids have fun on their bikes, it gives them confidence. The size of bike you choose should be based on the rider’s inseam length, not according to their age alone, as every child is different. As a leader in the best bikes for kids, please follow our step by step instructions so you can find what bike size fits your kid.

Kids size guide

Kids' Bike Fit Step by Step Guide

What you’ll need:

  • Tape measure (at least 36 inches/90 cm long)
  • Pen and paper
  • STP series inseam guide (see below)

STEP 1:

Have the rider stand with their back and heels against the wall. Make sure their legs are straight.

STEP 2:

Using their fingtertip, ask the rider to feel for the bone that sticks out the most at the outside top of their hip joint. Have them hold their finger on that spot.

STEP 3:

Have the rider lift their knee up to a 90-degree angle, while their finger is still on their hip joint. Have them repeatedly and slowly lift and lower their knee to confirm the location of the outside top of their hip joint: this is the pivot location.

STEP 4:

Once the spot is confirmed, have the rider keep their finger on the pivot location, and lower their leg to the straight position.

Measuring from hip to bottom of leg

STEP 5:

Take the tape measure and measure from the middle of the rider’s foot, up to their fingertip. Write this number down.

STEP 6:

Use the STP Series Inseam Guide (below) to find the right size bike for your rider!

Giant Liv STP Rider Inseam Length Guide

Kids' Bike Fit Seat Height and Reach Guide

Once you’ve figured out the right size bike for your young rider, you’ll want to adjust the seat height so they can feel confident getting on and off the bike and also feel safe while riding. You’ll also want to adjust the reach to the handlebars to put the rider in a good position.

Seat Height

Seat height for new riders and kids learning how to ride:

The seat should be set low enough so the rider can rest their feet flat on the ground when they’re seated on the saddle.

This makes getting on and off the bike much easier and also gives them confidence that they can easily reach the ground if they need to. This is a great technique to use if the child is sizing up to a bigger bike to get them used to the new size.

Girl standing over bike feet on ground

Seat Height for Experienced Riders

If a child has been riding for a while, or is used to their new bike at this point, the seat height can be adjusted higher to make pedaling easier and more efficient. A good place to start is to adjust the seat height so that when they are sitting on the saddle, they can still touch the ground with their toes.

Make sure you check that the seat post is NOT extended beyond the minimum insertion mark. If you see the minimum insertion line on the seat post sticking out of the bike, they may be on a bike that is too small for them. This is a safety issue.

Girl standing over bike toes touching ground

Handlebar Reach

The proper reach will put the rider in a position so that their upper body leans forward slightly. They should be able to comfortably hold their head up and rotate it for good visibility.

The rider's elbows should be slightly bent to allow for a natural wrist position, good shock absorption, and full steering range.