What size bike do I need for my height? Choosing the right size for your bicycle or for your kids is very important. A bike of improper size can prove to be a misery and even cause discomfort. It can negatively affect posture and even cause back pain. While a correct size bike is an asset and you can exercise on it comfortably. Bicycles come in different types- each meant for a different purpose, like Standard, Hybrid, Commuter, MTB and TT. Then, under each Type, there are different sizes. Before choosing the bike size, one must choose the bike type and then proceed to look at the charts. In general, the best way to find the correct size bike is to refer to the charts provided by the bike’s make or the company. Just like shoes, rings etc, there may be differences in sizes of bike based on the company that makes it.
General Rule to determine “what bike frame size do I need”. This is a general technique that can help you to figure out which size bike is the most suitable for your height and body proportions. It works for both men and women. However, since there may be some differences in specifications , you should actually consult the company’s charts before buying.
How It Works ? You need to calculate three parameters of your body. These will help to determine the correct bike size for your height. However, take note that these measurements should be standard and accurate, otherwise you may end up taking the wrong bike frame size.
Measure Your Inner Leg Length : Take a measuring tape and measure the length of your leg from the inside, that is from the crotch to the feet. This is the length of the leg below the the seat of the bike. This inner length should be 1 ” to 2 ” (inches ) above the height of the seat. Since the seat is adjustable in all bikes, it should be 2 ” above the minimum set height of the seat. Based on your measurement of Inner Leg Length, refer to a general bike frame size chart to select the bike frame for any bike type – Regular, Hybrid or Lady cycles. What is the Logic behind it ? This is to ensure that your crotch rests comfortably on the bike seat and you can reach down properly if you have to dismount the bike.
Ape Index : This is an index which is used to determine bike frame size correctly. Measure your Height and your arm span ( distance between the tip of your left hand to the tip of right hand in outstretched position ). Ape Index = Arm Span – Height.
Why is Ape Index used ? In some cases, your inner leg length measurement may lie between two standard measurement, so which bike frame size do you pick, upper or lower ? In that case, if Ape Index is positive, then choose the Larger Size and if Ape Index is negative, choose the Smaller Size.
This way you can precisely select the correct bike frame size for your height. What size bike do i need for my child ? It is relatively easier to choose correct bike size for kids. Most companies make bikes of different Wheel Diameter for kids based on Age and Inner Leg Length. So, you can read from it.
In case of a mountain bike, the Ape Index becomes much more useful. Ape Index determines how well you can handle the bike . If your arm span is not correct for the mountain bike you have, it can lead to difficulty and stress in riding a bike uphill. If you are aiming for a career in mountain biking, cycling etc, you need to do this step very carefully.