The correct frame height with bicycles is crucial for the “feel good factor” when cycling. There are various approaches for determining the correct bicycle frame size. Depending on the type of bike, this is a little different. In addition, there are many different scales on the Internet – we clean up and show you everything you need to know.
Which bike are you interested in??
- Cyclocross: https://www.fahrradreparatur.net/fahrrad-rahmenhoehe-rahmengroesse/#Rahmenh246he_am_Cyclocross_Rad
- Road bike: https://www.fahrradreparatur.net/fahrrad-rahmenhoehe-rahmengroesse/#Rahmenh246he_am_Rennrad
- MTB: https://www.fahrradreparatur.net/fahrrad-rahmenhoehe-rahmengroesse/#Rahmenh246he_Mountainbike
- Fitness bike: https://www.fahrradreparatur.net/fahrrad-rahmenhoehe-rahmengroesse/#Fitnessbike_Trekkingrad_Crossrad_Rahmenh246he
- City bike: https://www.fahrradreparatur.net/fahrrad-rahmenhoehe-rahmengroesse/#Stadtrad_Rahmenh246he
Wrong numbers – wrong calculator – wrong manufacturer information
Attention! A frame height calculator can quickly spit out a number for you. But this can deceive you. Because almost all modern bikes differ from the classic diamond frame model. You get the perfect result like this:
- Determine stride length and determine approximate frame height.
Those who break up here will only find a well-fitting frame with a little luck. We recommend: busy To you intensive with points 2 and 3 if the bike should really fit you.
- Find out which individual seating position is optimal for you. Are you sporty or do you want to drive comfortably? Are you more of a Seat giant or long-legged?
- Understand that Stack / reach approach, be careful when sloping and don’t be fooled by wrong manufacturer information. Read all the details further in the text.
One thing applies to all types of bicycles: trying out is about studying. Anyone who has taken a closer look at the topic will know that personal preferences also play a major role. That is why it is always worthwhile to test drive before buying. And it is only through personal experience on the bike that you can say with absolute certainty which frame geometry suits your individual body type.
First we will give some general tips on the correct frame height on the bike (→ calculate children’s bike size). Finally, we deal in detail with the new stack / reach approach, which is universally applicable for all types of bikes and is also used for bike fitting.
What sizes are there on the frame?
The most important sizes are the frame height, stride length, stack, reach, wheelbase … the definitions one after the other and why these values are important.
Definition of frame height and sloping
Frame height is the classic measure of the size of a bike. The frame height theoretically indicates the value from the middle of the bottom bracket to the end of the seat tube. Frame height is actually only important in the sense that the length of the top tube (and thus the distance from the saddle to the handlebar) increases proportionally to the frame height.
In addition, it has become established in the modern bicycle industry to build the frames sloping backwards (sloping) – that’s why the frame height only gives a theoretical value. Now the actual length of the seat tube becomes shorter. Although the frame does not shrink in geometry.
With the sloping top tube, the seat tube becomes shorter, and with it the measured frame height. However, the decisive factor is how high the theoretical frame height would be with a straight top tube. The stronger the sloping, the more you have to correct when calculating.
Frame manufacturers (almost) always indicate size (b), not the relevant size (a). The most Online computers take this fact into account. However, this is always an estimate, since not all mountain bikes, racing bikes, etc. have the same angle in sloping.
Definition stride length
The stride length defines the distance from the sole of the foot to the crotch, measured in cm. Everyone has a shorter or longer stride regardless of their height. Some people have legs that are proportionally longer than their height. Therefore, it is not too bad for you to determine the stride length instead of just the body size. Now measure stride length.
Why is it important? Well, let’s consider the fact that the top tube length is related to the frame height of the bike. Let us assume that we are dealing with a "long-legged" person – although one has a relatively long stride length, the relative height of the torso and upper body decreases at the same time. With bicycles, however, the top tube length increases with a higher frame height. That means, if you don’t take into account your own physical uniqueness, you can make a big mistake here. So it would be more worthwhile for a long-legged person to reach for a smaller frame size and adapt the saddle for it.
Definition of stack and reach on the bike
With this new approach, the frames of all manufacturers can be compared. Because here sloping has no chance of spoiling us. That is why the topic of bike fitting has established itself – where it comes down to finding the right indiv as precisely as possible >
Frame height S, M, L and XL – what do these sizes mean
Bicycle manufacturers often also specify their bicycle sizes in clothing sizes such as S, M, L and XL – sometimes this is even the only size specification for the bicycle sizes. Which body size is suitable for which bike size can vary from manufacturer to manufacturer – for example, a frame of height M sometimes corresponds to another frame of height L or vice versa. Sometimes there is also a specific indication of how tall the driver should be (e.g. between 175cm and 185cm). If not, you should get information from the manufacturer of the bicycle or the manufacturer of the frame and, if necessary, ask the dealer.
All in all, such sizes are only very rough estimates. If you are serious about cycling and do it more often than every few months, you should take a closer look at the frame geometry values.
Calculate frame height – how do I determine the optimal value?
Here you can get your optimal frame height calculated. You only need two criteria for our calculator: your stride length and your desired bike type. This gives you a guideline that you can round up or down depending on your individual preferences. In the further course of this article we will explain how you proceed with the measurement and what else you should know if you want to measure the exact frame height.
General determination of the frame height of a bicycle
Measure your stride length and multiply this value by 0.226. That’s how you calculate it theoretical frame height in inches (1 inch = 2.54 cm). If the calculated value is between two frame sizes, you should choose the smaller frame for a sporty driving style and the larger frame for a leisurely or tour-oriented driving style.
Measure frame height – determine bike size
At this point we would like to give you all the information you need to find out your suitable frame height yourself.
So I measure the stride length correctly
The stride length should be measured very precisely so that the calculated result can really give a realistic statement about the correct frame size of the bike. The greater the deviation, the less precise the calculated value is.
Your stride should have a value of approx. 65cm to 95cm his. On average, the stride length increases with body size, see the following diagram (approximate estimate).
Ultimately, the calculated frame size is only used as a guide.
It is best to stand barefoot on a straight wall or door. Then you press in (really press) book between the legs. The book must fit as if you were sitting on a bicycle saddle. Now you measure from the top of the book to the floor. The best thing to do is to get help – because pressing and measuring at the same time is not that easy.
Now we are dealing with the last crucial topic. The riding position is the second important factor in the equation after your size. After all, a 1.86m tall rider with an 88cm step length on the racing bike can be recommended a different frame height than on a trekking bike.
In our diagram there are three levels from very sporty (racing bike / triathlon) to sporty to comfortable. Depending on your size (division of stride length into giant seat, average length and long legs) and your desired riding position, these values result:
- You sit very sportily with a stack / reach ratio of less than 1.4
- You have a sporty posture without contortion with a stack / reach ratio of 1.4 to 1.55
- One sits more comfortably with a stack / reach ratio of 1.55 and higher
Tips for a perfectly fitting bike
We have the following tips for you if you are still undecided.
- Each bike of any size can be further customized. A longer stem and the flexible seat post (height of the saddle) continue to give you a lot of leeway, even if the bike does not fit you to the cm.
- Remember that a smaller frame is more sporty and a larger frame is better for touring. Virtually each of us is between two frame heights and can either round up or round down its value – depending on what goals and ambitions you have personally.
Mountain bike frame height
Frame height on the racing bike
Frame height on the cyclocross bike
The special racing bike type Cyclocross strives for a similar seating position to that of the racing bike. However, sitting on the cyclocross is either a little more comfortable because you are planning a long tour or more sporty if you are doing short tours through the forest. Depending on the objective, take a bike with a number smaller or larger. In principle, however, the frame size is calculated as with the racing bike, e.g. 80cm * 0.665 = 53cm (optimal frame height). The rule also applies here that a small bike (e.g. 52cm frame height) would be more suitable for sporty driving. In this case, the next larger bike should be used for long tours, e.g. 55cm frame height – depending on what the current offer in retail looks like.
See also more information about the racing bike frame height.
Frame height fitness bike / trekking bike / cross bike
The optimal frame height for an everyday bike, like fitness bikes, trekking bikes and cross bikes are mostly used, is le >
Sometimes the optimal frame height for trekking bikes is equated with racing bikes. However, a frame height that is one or two centimeters smaller than that of a racing bike is often suggested for the trekking bike. It often happens that trekking cyclists ride two or three sizes above their “ideal size” and are satisfied with it. The general rule is: with a larger frame you sit more comfortably, with a small frame you sit sportier.
A city bike is characterized by its upright sitting position. This is ideal for short distances in the city. Therefore, it is recommended to round up the calculated frame height for an upright position.
Multiplies the value of your stride length by 0.65. This results in the optimal frame height for the city bike (city bike). With a step length of 82cm this results in an optimal frame height of 53cm. So choose a bike with this frame height or a size larger (up to 2cm).
The body sizes are only guidelines. Depending on whether you are a giant or not, this can differ from reality!
Stack and Reach – The New and Precise Process
This new approach from bike fitting is the most precise method to find a suitable frame. Because regardless of the individual frame geometry of the bike type and model, you can calculate the relative position of the driver’s legs and arms in the sitting position.
The vertical height of is measured Bottom bracket to handlebar (stack).
The horizontal distance from Bottom bracket to handlebar (reach) indicates the length.
Often, frame manufacturers only specify the stack and reach to the top of the head tube. This is logical, because the frame manufacturer cannot know where the stem ends later and how long it is. In some articles or pictures we also refer to this measurement variant. In principle, both options are correct, but the variant up to the handlebar is more precise. With the variant up to the head tube, you can flexibly play around the length, angle and height of the headset to have a few millimeters of play.
That is actually the whole magic of frame geometry – in two numerical values. The cyclist only needs the horizontal and vertical position of the saddle compared to the bottom bracket to determine the ideal seating position.
However, it is difficult to find the right values on your own. Stack and reach come from bike fitting and it’s about perfectionism – not only frame geometry, but also body geometry is considered here. Only in an individual seating position analysis can you really find out which relation of stack and reach fits the individual body shape, mobility and driving behavior of the driver. Nevertheless, a rule of thumb has established itself for the determination of stack and reach, which we present below.
Determine your own stack and reach
If you want to determine without a bike fitting stack and reach, we have the following rule of thumb for you. With this, the right bike can be determined quite precisely based on the stride length and seat giant / long leg. At least you get a clue that is more universal and more accurate than traditional frame height calculations.
The universal rule of thumb for calculating the stack is:
S (stride length) x 0.69 = stack
This is quite obvious since Stack indicates the distance from the seat to the pedal. The formula for calculating reach is a little more complicated:
Stack: StR quotient = reach
So you first need the stack value and then divide it by a theoretical StR quotient (stack-to-reach quotient). Some formulas simply use the value 1.5 for this quotient – but this is only the “average value”, meaning for a “standard” person.
The individual stack-to-reach quotient
We therefore use an individual STR quotient. You determine this based on two factors:
- Athletic or Cozy. For sporty drivers, the quotient should be between 1.35 and 1.45 move. A quotient between 1.45 and 1.55 stands for a more moderate, but still dynamic driving style. A quotient between 1.55 and 1.7 is suitable for a comfortable driving style, i.e. on a city bike.
- sitting giant or long-legged friends. A giant sitting should now place its quotient on the lower spectrum, while the long legged should go to the higher spectrum. Depending on how far you deviate from the “norm”, you go higher or lower.
With the right stack-to-reach ratio, you sit perfectly in the saddle
Let’s take a long-legged person, for example, who uses a moderate driving style. A StR quotient of 1.55 is therefore suitable. But it can also make sense to use an even higher quotient. As I said, this is just a rule of thumb – you also use two factors, both of which are difficult to name with an exact value.
Stack-to-reach ratio on the bike
Alternatively, you can take the stack and reach from a bike – if available – and use it to calculate the bike’s StR quotient by dividing stack by reach. This way you know whether the bike is suitable for a sporty or comfortable ride and whether the frame geometry is more suitable for a giant seat or a long leg.
Do you have any other tips on how to determine the correct frame height? Feel free to write us in the comments.
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