Measure step length, determine frame size

If you want to buy a new racing bike or triathlon bike, you will at some point be faced with the question: What frame size do I need? The right frame height can be determined above all via your body size and inner leg length (or inseam height). In this post we will show you how to do it.

Measure stride length: Here's how

1. All you need is the right measuring tool: a folding rule and a spirit level are ideal. If you don't have a spirit level handy, a book can do the trick.
2. You should take off your shoes. If you have thicker trousers, it is also advisable to take them off. Sounds strange, but depending on how your pants fit or are cut, it affects the result too much.
3. Now it is measured. If you measure with a spirit level, you should pull it up as horizontally as possible between your legs. However, it works the same way with a book or catalogue. Before doing this, you should stand against a door or wall so that the top edge of your "measuring instrument" is exactly parallel to the floor.

Important: Don't just apply the spirit level loosely, but actively pull it up into your crotch. Some pressure should be felt in order to do justice to the later saddle pressure.

4. Measure the length from the floor to the top of the spirit level (of the book). If you have an assistant in your area, let them help you with the reading.
5. Write down the value – done. The measured value is now your so-called step length or step height.

To determine the correct frame size, your measured step height is now multiplied by 0.665. This results in the theoretical value of the frame height in centimetres. The frame height indicates the value from the middle of the bottom bracket to the upper edge of the seat tube (German measuring method). For triathlon bikes, the frame size should usually be one size smaller than the calculated racing bike size.

This table can (depending on body size) also serve as a guide:

Different size designations

With some manufacturers, size designations are no longer defined in centimeters, but in the XS-SML-XL format. Here it is advisable to look at the respective geometry table of the corresponding designation and compare the value. As an aid, you will now find a size recommendation from almost all manufacturers depending on your measured values.

Bike fitting - the optimal seating position