STP Bike Sizing Guide

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, allowing 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 optimised 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 authorised 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 handlebars 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 24 is 140mm long to properly fit riders for that frame size. The smaller STP 20 uses a 105mm crank, more appropriate for shorter riders. 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.

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 authorised Giant retailer for professional assistance.