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Correct bike fit plays a critical role and sets a foundation for a positive riding experience with young riders. Whether it’s a road bike, mountain bike or all-rounder, a good fit ensures comfort and control and allows young riders to maneuver the bike properly. Mountain bike skills such as cornering and riding bumpy terrain are easier to master when the rider’s body and bike are in balance. On a road bike, power output and efficiency are optimized with a proper fit. For young riders just starting out, a safe and positive riding experience on a bike that fits not only cultivates confidence but also gives them a great start on making cycling a lifelong hobby. Follow these guidelines to help find the correct bike size and fit for your child. These steps cover the basics. For more precise bike fitting details and questions, we recommend visiting an authorized Giant retailer

Children often grow in fits and starts, which makes buying a larger bike seem like a sensible choice. But there are downsides to this practice. Larger sized bikes usually have a longer reach and higher standover. If a child must stretch to reach the handlebar or has trouble maneuvering because the top tube is too high, it will be harder for them to develop their skills and have fun. Also, parts such as the crank and handlebar are carefully designed and matched to fit particular frame sizes. For example, the crank on a Giant STP 26 is 155mm long to properly fit riders for that frame size. The smaller STP 24 uses a 140mm crank, more appropriate for shorter riders (around 140-150cm tall). Yes, children grow up fast—but choosing the wrong bike size will make their experience less enjoyable. Choose one that fits them today and they’re much more likely to start off on the right foot.

Youth bikes are often available with different wheel diameters for different heights. For example, Giant STP mountain bikes are available with 20”, 24” and 26” wheel diameters to meet the needs of young riders between 110cm and 160cm tall. Choosing bike size by age is not recommended. A more precise way is to measure the inseam height and refer to our inseam height-size table to determine the correct size.


  1. Ask your child to stand with his or her back to a wall, feet at shoulder width while wearing the shoes they will ride in.
  2. Place a thick book between the child’s legs, spine side up. Have them raise the book and hold it against the wall as if they were sitting on it like a bike saddle.
  3. Mark the height of the book spine on the wall.
  4. Use a tape measure to determine the distance between the floor and the mark on the wall. This is the inseam height.
  5. Use our inseam height-size table to determine the correct size.


After determining the correct bike size for your child, the next step is adjusting saddle height. One thing to consider is how much experience the young rider has. Here are our recommendations:


For young riders just getting started and looking to build their confidence, the first step is to make sure their feet can be firmly planted on the ground when seated in the saddle. This allows the rider to stop and start easily, get on and off the bike, and quickly get both feet on the ground when they lose balance.

Experienced Riders

For young riders upgrading to a larger bike or something more capable like a youth-sized road or mountain bike, the first principle of setting saddle height is to make sure they can touch their toes to the ground when sitting in the saddle. A slightly higher saddle allows for more power and efficiency.

As you can see, saddle height for kids will differ based on riding experience, the type of bike they are riding and other factors. These are guidelines, but we suggest trying different methods and paying close attention to your child’s comfort, control and confidence as you make adjustments.

When this happens, parents often opt for the larger sized bike so the child can “grow into it.” However, as mentioned earlier, there are other factors to consider. If the child is forced to ride a bike that is too large, their comfort and control can be compromised. If you’re unsure of the correct size, please visit an authorized Giant retailer for professional assistance.