Bike fitting: finding the right frame size and the most efficient seating position.

Interview with bike expert Klaus Jockers

The correct seating position will not only make riding a bike more comfortable, but can also increase your performance and prevent physical problems. In this interview, bike dealer Klaus Jockers reveals what you should pay attention to when fitting your bike and which is the right frame size for you.

Bike fitting: determining the frame size

If the sporting aspect is the most important thing to you when cycling, you can definitely benefit from a proper bike fitting. But there is a lot to consider: Klaus Jockers is the owner of the bike shop Funsport Munich and part of his daily business is advising his customers on which bike suits them best. In an interview, the enthusiastic mountain biker explains what bike fitting, the proper seating position and the right frame size are all about.

Bike fitting: this is what it's all about

As the name suggests, the goal of bike fitting is to adjust the bike to best suit the individual rider. This includes the proper frame size as well as the correct saddle and handlebar adjustments. Klaus Jockers explains the details.


So what exactly is bike fitting?

Klaus Jockers: “Bike fitting is the calculation of the supposedly ideal sitting position on the bike, taking into consideration arm length, leg length, shoulder width, knee position and load points on the soles of your feet.
This is certainly interesting for top athletes in order to improve aerodynamics and pedalling efficiency. As an athlete, you have to determine for yourself whether the calculated position works for you or if it restricts you in other ways.
For the recreational cyclist it is debatable whether or not it is worth the effort, since taking measurements is not a guarantee that you will feel comfortable on your bike afterwards.”

If you want to buy a bike online, as a hobby cyclist you can usually find a reasonable sitting position by using the frame size and the correct saddle and handlebar settings. However, if you have any ailments or if you cycle at a competitive level, you should definitely consult your local bike store.

Athlete on road bike
Top athletes can increase their performance through a proper fit.

What is the perfect biking position?

“From my own experience, I can say that there is no definitive right or wrong. Of course there are certain standard positions that work for most people, and if you have no experience with sitting positions, they are a good starting point.
But you cannot rely solely on measurements and simply determine that rider ‘A‘ with an arm length of ‘A‘ and a leg length of ’A‘ needs the frame size ‘A ‘. Every person has a different level of mobility. This is due to different back, pelvis and hip shapes as well as leg postures and knee mobility. Even the ankles and soles of your feet play a role in this.
In my opinion, bike fitting is therefore only effective if the athlete has the opportunity to test the one-off bike designed for his body measurements for at least 500 kilometres. And that includes long-distance, uphill, downhill and, with mountain bikes, especially demanding terrain.
It often takes the customer many kilometres to determine whether the bike is comfortable or not. The best seating position is pointless if you have a problem with your knee or shoulder and your fingers and toes fall asleep.”

How do I find the right position on my bike?

“The trained eye and a few adjustments by a specialist often work wonders.

However, it is also very important that you as a biker develop a feeling for yourself and listen to your body. You should try to adjust the position over and over again - always in small increments - until it feels like you are as close as possible to the optimum.
There is no one perfect position though. For example, a slightly higher saddle is always going to be more effective while going uphill compared to riding on flat land. And if you are trying to go as fast as possible, adjusting the saddle a little forward is naturally more effective. Strictly speaking, you would actually need a switch on the handlebar that moves the saddle in all directions - that's an idea for the future.”

Determining the correct frame size

Once you have decided on a bike, one of the most important subsequent questions is which frame size is the right one. We asked Klaus Jockers about this topic.

Which factors are important in finding the right frame size?

“The top tube length, head tube length and the angle of the seat tube are the key parameters. You always have to consider how sporty you want to sit as a rider and what you want to do with your bike: do you want to ride fast, sit comfortably, ride more uphill or do a triathlon? Should the bike be suitable for urban use, flat terrain or mountains?”
Bicycle frame schematic
Even if I know all of the customers' requirements, I don't feel comfortable calculating the correct frame size on the spot. I like to do this at my leisure and inform the customer once I'm ready. Then we go over my result together and pick the right frame.
At least that's how it works with sports bikes. If you want to buy a trekking bike or a standard mountain bike that is only available in three to four sizes anyway, you can of course calculate the right size relatively quickly".

Can I calculate the frame size by myself?

“A cyclist who's maybe had 10 good fitting bikes before and has more than 100,000 kilometres under their belt can probably decide for themselves.
Otherwise I would advise against it, as the geometry is different with each manufacturer. Even manufacturers internally have very different geometries for the individual model lines, depending on the intended use of the bike.

If you still want to find the right bike size on your own, you can roughly determine the frame size with the following calculation.”

This is how you can determine your frame size

The correct frame size depends on your stride. You can easily calculate it:
1. Pick a flat and even surface and stand up straight, without wearing shoes or trousers.
2. Take a level (or a book), pinch it between your thighs and pull it all the way up.
3. Now you can measure the distance between the top of the level (or book) and the ground.

The next step would be to multiply your result with the corresponding factor for the type of bike you want:

• Road bike: inseam x 0,665
• Mountainbike: inseam x 0,226
• Trekking/Touring bike: inseam x 0,66
• Sports touring: inseam x 0,61
• Downhill MTB (full suspension): inseam x 0,225

The result is your bicycle frame height/size. Both centimeters and inches are common measurements for frame sizes. If you measured in cm and want to get to inches you divide by 2.54. For inches to cm you multiply accordingly.

You should really only view this result as a point of reference though. As Klaus Jockers said in the interview, frame sizes vary from model to model. You best visit your local bike shop for guidance.

If you want to buy your bike online, many manufacturers offer a frame sizing calculator on their website which takes into account the specific geometry of their model range.

Why are there different multiplication factors for different types of bicycle?

“The multiplication value is designed to deliver the true frame height. A 48cm MTB frame for example suits the same size rider as a 56cm road bike frame.
This is simply due to the fact that you need more maneuverability on the mountain bike. You might have to jump off in a pinch or move around in some other way where a tall frame could be in the way. On top of that, you have really tall suspension forks that make the bike very tall to begin with.
Since the frame sizes vary so much between the different types of bicycles, many manufacturers have started to label their frame sizes from XXS to XXL. This allows them to offer transferrable sizes across the different bike categories, even though the actual frame heights differ significantly in cm or inches.”

What happens if I choose the incorrect frame size?

“If the frame is too small, you are going to run into the issue that you are sitting too far forward in relation to the bottom bracket. You will always feel like you are on a child’s bike and you will never get good power transfer on your pedal strokes.
If the frame is too large, you will often have trouble handling the bike - you will feel overwhelmed, especially in difficult terrain.”

How do I sit correctly on the bike?

Frame height is not the only determining factor for feeling comfortable on the bike, while also avoiding health risks. Another key factor is the proper adjustment of your saddle and handlebars.

The saddle height depends on the length of your legs. Your knee should never be higher than your thigh during a round pedalling movement, as this will decrease your efficiency. If the saddle is too high, your pelvis will slide from side to side, resulting in back pain.

In theory, the ideal saddle inclination is perfectly level, as it distributes the pressure best. But not everyone feels comfortable like this.

The angle of your handlebars depends on your body type, wheel type and bike handling preferences. Your back should be in a natural position. Your riding style determines the angle of your arms.

This is how you sit on your bike correctly

The correct saddle position is important for both good power transfer and to prevent knee pain.

This is how you adjust your saddle correctly

1. Turn your pedals until they are in a 6 o’clock position (one at the top, one at the bottom) and sit on the saddle.
2. Place the ball of your foot level on the lower pedal and extend your leg.
3. Adjust the saddle height so that you can no longer push yourself out of the saddle in this position. When riding, the heel will be raised automatically and the knee will be slightly bent.

This is how you adjust the angle of your saddle

1. Turn your pedals to a horizontal position (one in the front and one in the back).
2. Place the ball of your foot on the front pedal.
3. The kneecap and pedal axle should be perpendicular to the ground. You can also help yourself with a plumb line.

This is how you adjust the handlebar angle

The adjustment is correct when your pelvis is slightly tilted forward, and your back aligns with the natural position of your spine as you grip the handlebars.

You can then tailor the handlebar height or angle between upper arm and upper body to your riding style. A smaller angle means a more upright the sitting position. Air resistance is significantly higher and going uphill is more strenuous.

  • Competitive riders: 80° to 90°
  • Touring riders: 70° to 90° (ideal long distance position)
  • City commuters: not more than 60°
  • City cruiser/relaxed : 20° to 30°
  • Finding the right shop

    The bottom line: there is no ‘one size fits all’ approach to bike fitting. If you are a professional athlete it’s best to get an individual consultation, pay close attention to your comfort level, try out your sitting position over an extended time period and adjust it as needed.

    Do you have any advice for people who are looking for the right bike?

    “The only advice I can give you is to seek out a bike shop with staff that care about selling the RIGHT bike to the customer”.

    Who is going to help me if I want to optimise my seating position?

    “After you purchased the bike, every dealer should be set up to help you out with your desired changes or with eliminating existing issues“.

    Enjoy your new bike!

    owayo bike jerseys
    In our shop you will find an amazing selection of bike jerseys which you can also customize yourself

    Now go out and have fun finding your new bike. Do you still need the right sportswear to go along with your new set of wheels? owayo offers great cycling jerseys, jackets and shorts, which you can also design individually. Be prepared on your next group cycle or bike trip.

    Are you interested in more articles about cycling? Then read our article on the subject of compensation training in cycling.

    We thank Klaus Jockers for the interview and wish you a pleasant ride!

    Images: Cover image: © iStock/ RyanJLane; Images: © iStock/ Mypurgatory- years; © iStock/ mel-nik