Felt IAx Advanced Ultegra Di2 Triathlon Bicycle

How To Measure?
How To Choose Right Bike Size

The right sized bike is THE most important thing to maximize your performance, enjoyment, and to also ensure you stay injury free. Generally, two measurement required to choose the correct frame size.

1.Your Height
2.Inseam Length

To measure your height, stand against a wall and mark the wall with a pencil so it’s level with the top of your head. Then measure from the ground up to the mark. Having someone assist you makes this a lot easier and a lot more accurate. For your inseam/inner leg measurement, stand against a wall and using a book, hold it in between your legs into your groin and make sure it’s flat against the wall. Measure the height from the book to the floor. These 2 measurements are typically sufficient to match brand specific size charts to help you arrive at a specific frame size, recommended by the brand.

In some rare scenarios – if your height and inseam leg measurements put you in-between two sizes, your upper body length would be the deciding factor in selecting the best size bike for you. Your upper body dimensions determine the ‘Reach’ and this affects how ‘stretched-out’ you will be along the top tube of your bike as you ride it. To work out if you have a long or short reach, you need to determine your ‘APE INDEX‘ which is nothing but arm span minus height.
A positive Ape Index (arm span > height), then we suggest you go for the larger bike sizes.
A negative Ape Index (height > arm span), then you’re probably more comfortable on the smaller size.

Arm Span is the distance between the tips of middle fingers of both arms outstretched at right angles to the body, measured across your back. Much easier if you have a friend do this for you.