How to Measure a Bike Frame: Simple Guide for Beginners

Do you love bicycles? If you love bikes then you must understand the beauty of outdoor cruises. Biking is a great sport with many health benefits. From boosting your immunity, increasing your reflexes, improving your response time, to giving the strongest cardio systems riding a bike is just the bomb.

However, before you can enjoy your bike, you must first get the right bike. The right bike must be comfortable, easy to climb on and off, and best for your needs. In this post, I am going to show you how to measure a bike; so that by the end of the day, you can get your own bike.

How to Measure a Bike Frame

The size of the bike is measured in line with the bike frame. The bike frame size is determined by the exact length of the tube that supports the saddle. This is also called the seat tube. Let us see how to measure a bike frame.

Step I: Locate the Seat Tube

Start by locating the top of your bike’s seat tube. This is usually the exact point on which your seat joins your bike frame. It is the same as the junction that the saddle’s post enters into the bike frame. Some people have always referred to it as the part where the bicycle’s seat is connected to the mainframe.

Step II: Locate the Bike’s Bottom Bracket

The next thing is to trace the bikes bottom bracket. This is usually found at the bottom end of the bike’s seat tube. It is a round/cylindrical component that’s made out of steel alloy. More specifically, it is the part that holds the pedals.

To find it, go to the pedals. Find the part that the bike’s pedals are connected to the frame of the bike. That is the bottom bracket of your bike.

Step III: Get a Tape Measure and Measure

Once you identify the bottom bracket and the seat tube, you should take your tape measure and determine the exact measurement between these two components. The measurement should be taken from the seat tube to the bike’s bottom bracket. As you stretch out the measuring tape make sure that you direct it to the center of the bike’s bottom bracket. Do not focus on the pedal or outside.

Step IV: Take the Reading and Note Down

You can now take the reading and note it down. Depending on the type of unit that you were using, it is important to convert your measurement accordingly. The best measurement to go with is inches. Some bikes are also designed in millimeters. Remember that in one inch, there are 25.4 millimeters.

How Do I Convert the Measurement?

If you have inches then you can convert them into millimeters by multiply the inches that you have measured by 25.4mm. Yet if you have millimeters, you can easily change them into inches by dividing your measurements by 25.4mm.

NOTE: Bike frames are usually measured in either inches or millimeters. Therefore, this should work most of the time.

How to Measure a Bike: Additional Tips

The basics of measuring a bike and a bike frame starts by measuring the distance between the seat post and bottom bracket. However, it doesn’t end there. There are some very crucial tips that will come in handy if you want to learn how to measure a bike. First, you should sit on the bike. While sitting on the bike, keep your eyes out for the following thing to get a perfect fit.

Check at the bike’s pedal when it is at its lowest point. The lowest point is when the pedal goes down and closes in on the ground. At this point, a perfect fit will allow your foot to retain its flat position on the bike’s pedal. In addition to that, your leg should achieve a full stretch of extension. Next, when the bike’s pedal hits its highest point, your knee shouldn’t achieve the perfect horizontal. Instead, it should retain a slight slash that prevents it from straining the leg’s knee cap.

NOTE: To check if this works out, here is a simple trick that you can make use of. Sit on your bike. Set your bike in an upright position. Then check if your toe can easily touch the ground. Make sure you maintain the same position while doing that. The bike should also be upright.

How to Tell if the Bike Fits You

Going by the tips that have given you here, determining if the bike is a perfect fit is really easy. Simply adjust the bike’s seat to fit these top criteria. Once the position meets the criteria that I have laid in the “additional tips” section, your bike will be a perfect fit.

How to Adjust the Bike’s Seat

Now we have seen that the bike’s seat plays a major role in getting a perfect fit. We should learn how to give it the perfect adjustment. In this section, I will show you how to adjust the bike’s seat perfectly.

Step I: Determine the Height

You need to know the exact height that your saddle should sit on. To do this, you need to measure your pubic bone height.

To do this, get a pal to help. Then plant your feet on the floor. Make sure that they are bare and that you have set them on flat.

Now spread your feet 10 inches apart. While on that position, let your pal take a measuring tape and measure in between your legs straight up to your crotch.

Take the resultant measurement and note it down. Then like we did with the bike frame, convert it to suit your units.

You can then take the measurement of the bike’s frame and determine how any inches or millimeters you need to subtract or add for your bike’s height to fit.

Step II: Determine How the Seat’s Post Adjusts

The next big thing will be to adjust the seat post. To get the right results, you’ll need to do this properly. This means that you must determine how your seat post adjusts first. Basically, all seat posts can be loosened and properly adjusted at their junction. The junction is the place where the saddle post enters the bike’s frame. In this section, you will find a quick-release lever that’s set at the base of the bike’s seat post. This lever is one that can be opened and then adjusted before being fixed at the point you choose. It is made of a small bracket that comes with a screw. The screw helps you to secure the customized setting. If the seat post, on the other hand, is bolted, you can use an adjustable wrench to make the saddle post lose before adjusting it.

Step III: Adjust the Post to Desired Height

Now carefully adjust the seat’s height to the measurement that you took. You can do this by gently sliding the saddle post either up or down until it hits the ideal measurement. Once the post hits the right height you can mark the place. Marking the place will enable you to easily find the perfect height in case the post slips out or if someone else was to ride too.

Step IV: Tighten the Seat Post on the Mark

Finally, you can tighten the seat’s post on the mark. Make sure that it is locked in position and use the adjustable wrench to tighten until there seat stops to move completely. Leave some breather that allows you to undo the tightening if the need arises.

Why Should You Measure a Bike?

There are many reasons why you need to measure your bike frame before you buy. Some of them include the following:

Proper Fit: Measuring the bike before you buy will ensure that you get a bike with a proper fit. You will end up with a bike that suits your stature, size, and height.

Comfort: With a bike that fits you perfectly, you will get a better riding experience. This way, you remain comfortable. You will prevent exhaustion and painful joints.

Control: More importantly, you will gain better control of your bike. In case of an emergency, fast reaction and control will be very easy. You will be fast and precise.

NOTE: People vary in size, stature, and height. However, if you are between say 5 feet 8 inches and about 6 feet tall you will find a bike that has an 18-inch frame very comfortable. Shorter guys should, however, try bikes that have 16-inch frames. For taller people, 20-inch frames or larger models have been recommended.

What You Should Know When Looking for a Proper Fit Bike

While you have seen all the tips that you need to get the best fit bike, it is important to learn a few other tips that will also determine what you will eventually end up with. Here what you should know.

What You Will Pay

If you want a proper fit bike, you must expect to dig a little more into your wallet. Proper fit bikes need to have the right size and perfect design. Even so, you can always watch out for an offer or a discounted price so that you get the best bike at the most affordable price. You can also do a comprehensive shopping as that gives you the big picture.

If You Buy Online

In case you buy online, measuring your bike can be practically impossible. In this case, you can go with the tips that we have listed. However, once you receive the package, you must confirm if it fits immediately. If you cannot adjust it, reach your sellers and trigger the return clause. This will give you a better chance.

It Takes Time Too

Contrary to what many people think, you won’t feel comfy on the bike the same day that you adjust it. No. It takes time to fall in place. That’s why experts will always advise you to practice with your bike more. By practicing, you will feel comfortable sooner than you thought.

Talk to the Pros

If you don’t have the faintest idea of what to look for or how to go about measuring your bike, you should talk to the pros. Your pals and loved ones who love bicycle riding will be ready to help you out.

You can always talk to them to see what you can do differently and to learn new tricks right on the track too.

Get a Biking Group

If you need to learn your new bike faster and to develop better bike handling skills, you should ride in a group. Find a rider group that suits you and join in the routine. This will make practicing fun. It will also help you to learn faster.

What Does a Pro-Fit Package Include?

A profit bike package comes with different terms. It covers a detailed conversation with the fitter on the type of riding style and experience that you need. It also includes a brief assessment of flexibility and discrepancies in length.

The packaged might include also additional checks on different factors. Some of the factors that they look at are:

  1. Saddle width
  2. Shoe size
  3. Insole support
  4. Handlebar Size

Finally, the most comprehensive packs will demand that the fitter also assesses your form on the bike. They can then help you to make adjustments. They can adjust the following:

  • Cleat setup
  • The seat height
  • Pedaling motion
  • Handlebar/cockpit reach

 NOTE: To get the best results from working with a fitter, you must remain honest with your fitter about your medical history including injuries.


I hope that you can now measure a bike and get a model that actually suits you. Well, with the right knowledge, it is now simple. One thing that you must know is this. Measuring a bike doesn’t mean that you cannot fit on the other bikes. You could.

However, a bike that’s too small will leave you with very tired joints. One that’s too high will mean that you strain a lot. That’s why you need one that leaves you comfortable. This will be the bike that you can ride for long.

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6 thoughts on “How to Measure a Bike Frame: Simple Guide for Beginners”

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  3. Hi! This is my 1st comment here so I just wanted to give
    a quick shout out and tell you I really enjoy reading your posts.
    Can you recommend any other blogs/websites/forums that cover the same subjects?
    Thank you so much!


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