While pedaling, your knees should not hit the handlebars (too small), and your legs should not fully lock out at the bottom of the stroke (too large).
When standing over the bike's top tube with both feet flat, you should have at least 1 inch of clearance on a road bike and 2–3 inches on a mountain bike for safety. 3. Understanding Advanced Fit (Reach & Stack)
Road bikes are typically sized in centimeters (cm). 4'11" – 5'2": 47 – 50 cm 5'3" – 5'6": 51 – 54 cm 5'7" – 5'9": 54 – 56 cm 5'10" – 6'0": 56 – 58 cm 6'1" – 6'3": 58 – 61 cm bike buying guide size
Mountain and hybrid bikes are typically sized in inches or categorical sizes (S, M, L). 5'0" – 5'4": 14 – 15 inches (Small) 5'5" – 5'8": 16 – 17 inches (Medium) 5'9" – 6'0": 18 – 19 inches (Large) 6'1" – 6'4": 20 – 21 inches (XL) 2. Measure Your Cycling Inseam
If you are between sizes, or comparing different brands, look at "Reach" and "Stack" on the bike's geometry chart. While pedaling, your knees should not hit the
The vertical height from the pedals to the handlebars. A higher stack puts you in a more upright, comfortable position. 4. Sizing for Kids
Your height gives you a direction, but your inseam gives you precision. This is not your pant size; it is the distance from your crotch to the floor. Understanding Advanced Fit (Reach & Stack) Road bikes
The horizontal distance from the pedals (bottom bracket) to the handlebars. A longer reach feels more "stretched out" and aggressive.