Not directly, but it's the most important starting point for determining appropriate frame size. Your inseam guides the recommended standover height and helps calculate a suitable seat tube length range. However, other factors like your torso and arm length, and the bike's effective top tube, also play a major role in overall fit.

While the fundamental measurements (seat tube, effective top tube, standover) are the same, the emphasis often differs. For road bikes, seat tube length (C-T) is still a common sizing method, combined with ETT. For mountain bikes, especially those with very sloping top tubes and modern geometries, Effective Top Tube (ETT) and Standover Height are often considered more critical for sizing, as they impact control and clearance on technical terrain.

If you're between sizes, consider your riding style. If you prefer a more aggressive, nimble feel with precise handling, you might opt for the smaller size, which can often be adjusted with a longer stem or more seatpost extension. If you prefer more stability, comfort, and an upright position, the larger size might be suitable, potentially using a shorter stem. Always prioritise sufficient standover clearance, especially for mountain bikes.

Wheel size itself doesn't directly change how you measure the frame, but it significantly influences the bike's overall geometry and handling characteristics, which are designed around that wheel size. A frame designed for 29-inch wheels will feel different from one for 27.5-inch wheels, even if the frame's core measurements (like ETT) are similar. Always ensure the frame is designed for the wheel size you intend to use.

Historically, some women's specific designs aimed for shorter top tubes to accommodate potentially shorter torsos relative to leg length. However, modern bike sizing is increasingly unisex, focusing on geometry figures like Reach and Stack that better account for individual body proportions. The measuring process remains the same regardless of the intended rider gender; it's about matching your body measurements to the frame's dimensions.

For road bikes, aim for about 2-5 cm (1-2 inches) of clearance. For hybrids and commuter bikes, 5-7 cm (2-3 inches) is good. For mountain bikes, particularly those ridden off-road, you'll want more clearance, typically 7-10 cm (3-4 inches), to allow for quick dismounts and manoeuvring over rough terrain without hitting the top tube.

While height charts provide a rough starting point, relying solely on height is imprecise. Two people of the same height can have vastly different leg and torso lengths, leading to very different ideal frame sizes. Always combine height information with your inseam and potentially other body measurements for a more accurate fit.