First, get hold of a metre rule (folding ruler) and a spirit level. As an alternative to a spirit level, you can also use a book.
To avoid influencing the measurement, measure yourself without wearing shoes and trousers.
Pull the spirit level (or book) as far upwards as possible into your crotch (see illustration). When using a book, you should stand against a door or wall so its top edge is parallel to the floor.
Now, measure with the metre rule from the floor to the upper edge of the spirit level or book.
This measurement is your inseam (or stride length).
Step 2: Calculate the correct size of the type of bike you're looking for
Since different types of bikes have different geometries, knowing your inseam is important for calculating your correct size.
To do this, simply select the type of bike you're looking for from the overview below. You'll find a unique frame calculator for each type of bike (and alternatively a size table).
Here, you can enter your inseam length to get a rough recommendation for the optimal frame size for this type of bike. The adjacent table also helps you classify the measurements according to your height.
Already got a specific bike in mind? Step 3 will help you pick the right size frame for it.
Step 3: Finetuning with the Smartfit frame size calculator
Found the ideal frame size for the type of bike you're looking for after doing steps one and two? Already got a few bikes on your shortlist? Now it gets really clever because your arm length and the individual frame geometries from different manufacturers also play a role. This way, you can be sure your chosen bike fits your body dimensions.
Model & brand-specific geometries
The difference in geometry alone between a classic 'diamond' frame with an almost-straight top tube and a trapezoid frame with a sloping top tube gives an idea of how different the geometries of individual bikes of the same type (e.g. touring bikes) from the same brand can be. And then there are the different geometries (for the same frame size) from manufacturer to manufacturer.
This is why we've developed an online frame size calculator with the experts from the bike lab, which brings together body measurements, bike models and vast bikeﬁtting experience in an easy-to-use yet accurate calculator.
Stack & Reach
The ratio between frame height (stack) and frame length (reach) is important for determining the correct frame size. This ratio varies greatly between manufacturers and bike types, so it must be included in the calculator along with your body measurements.
Individual body measurements
We receive geometry data for individual bikes directly from manufacturers. However, the ratio between arm and leg length also varies from person to person, so these two values should also be included in the calculator.
How does the Smartfit calculator in our online shop work?
The Smartfit calculator is available for almost all bicycles in our shop on the individual product pages. If there's no Smartfit calculator available for your desired bike, this is most likely because we haven't received any geometry data from the manufacturer. In this case, you can still calculate your frame size using step 2. On the product page, simply click the "Which size is right for me?" button above "choose frame size".
1. The Smartfit calculator will open. First, select your gender and enter your height.
2. The tool will display the average leg length for your height. You can adjust this to your own leg length for a more accurate result. Remember, you already know your inseam from step 1 of this frame sizing guide.
3. Next, you'll see the average arm length. You can also compare this with your own measurements to get better results. You can find out how to measure your arm length directly in the tool (just click on the question mark in the image).
4. The tool then uses the Smartﬁt algorithm to calculate your ideal frame size for the specific bike. If the frame is sold out, it will suggest suitable alternatives (also from other brands).
Congratulations - that was it!
If you follow these steps, you can be sure you've found the right size for your dream bike before you put it in your shopping basket. You'll have way more fun on a bike that fits you properly – now all you have to do is get out and ride!