Bike Frame Size – How To Measure Bike a Frame Size?

Planning on getting replacing your bicycle or getting a new one? Then we have to say that you must make sure to have the right bike frame measurements if you want your purchase to be successful.

In order to find a bicycle that fits you perfectly, you must understand the measurements that determine your cycle’s frame. If you know all about your frame size, then you will be able to find a cycle that fits your needs and delivers the performance you expect from it.

And not just that, even if you just want to simply rent a bike, then knowing your measurements will help you choose the most ideal bike for you. If you think it’s excessive, then maybe you don’t realize that if the cycle you purchase isn’t catered to your size then you won’t feel comfortable or at ease riding it.

So, we came up with this article so you can get an idea of how to measure the frame size the right way. Before we start, you need to know that not all brands manufacture their cycles with the same sizing. So you will have to measure the frame with a few fundamental features and then you can go on and choose a bike that fits your needs.


The main numbers that define your bike’s frame

  • Seat tube length
  • Top tube length
  • Head tube length

So, these are the few measurements that we will tell you how to take one by one. You will need a clinometer to measure the angles, a measuring tape, a plumb line, and a long spirit level. Also, most of the bikes, mountain and otherwise are now measure in metric units. However, some brands still measure these bikes in inches. But we recommend you stick to metric units for maximum efficiency.

Seat tube length

The most common measurement that is used to determine the frame size of a bicycle is the seat tube length. It’s also known as the headline size. It’s very easy to measure and note that this measurement will greatly affect the rest of the measurements of the frame.

First, find the crank center from where it joins the bottom bracket. There is a line that follows the seat tube. You will have to measure that which is actually the seat tube. Some bikes have larger seat tubes while some come with extremely short seat tubes. It completely depends on your preference that what kind of bike are you looking for.

A seat tube length determines the entirety of your frame size. If you measure this correctly then you will never end up with the wrong bicycle.

Measuring top tube length

The top tube length indicates the distance of how far you will have to reach to have your hands on the bike handles. It has a very dramatic effect on how perfectly the bike fits your body and how comfortable you will be when riding it.

If you get a bike that is large for your size, then there isn’t much you can do to adjust the reach. However, if you buy a small bike then you can always adjust the reach by pushing your seat a little backward.

We found that determining the right top tube length is the difficult task of all. you can use a clinometer and an inch’s tape to determine the length and the angle of the top tube length.

Measuring head tube length

Subsequently, how well you will be able to fit on a bike also depends on the head tube length. This is the front part of the frame the fork fits through.

Usually, cycles with smaller head tube lengths are difficult to ride and far more aggressive. They don’t give you complete control of the speed and make the ride much bumpier. In the same way, a cycle with a higher head tube length is easy to handle, gives more control over the riding pace, and makes the biking experience a whole lot smoother.

It’s up to you which bike would you like to opt for. You will have to use the inch’s tape and measure the head tube size from one end to the other. Also, when measuring the head tube size, don’t forget to keep the size of the tires in perspective. It also massively affects the size of the frame.

Complicated, is it?

We are sure you must be thinking why is this all so complicated? It’s just a simple bicycle. But let’s be honest. A cycle’s geometry consists of a complex range of numbers that you need to fathom to the best of your ability.

Of course, you don’t want to end up with a cycle that adds no value to your performance. The regret of spending your money on the wrong bicycle is going to go a long way. So make sure when you’re choosing a bicycle, you put everything in perspective.

Added tips for measuring a bike’s frame design

  • Talk to a professional seller
  • Read online and see YouTube tutorials for more information
  • Check reviews on various bicycles on Amazon prior to the purchase
  • Always read specifications


Measuring the frame size of a bike isn’t as easy as you may have thought. As you can see, there are loads of measurements to consider and you need to ensure you don’t end up with the wrong numbers. Amazon has a wide list of best cycles for regular bikers that you can check out. Also if you feel confused about the frame size, don’t hesitate to get in touch with the manufacturer.

They will be able to simplify the entire process for you. Hopefully, this article has been helpful to you. If there is anything you would like to add in this regard, do let us know through your feedback below.

Last Updated on February 22, 2022