How to measure a Mountain Bike Frame | Choosing the correct Bike size

When searching for a new mountain bike, you should know some key measurements. These measurements adequately define the size of your MTB frame. And they ensure that the bike fits you according to your riding style. But how to measure a mountain bike frame, you might ask!

Some people think that with a few adjustments and tweaks, you can get an MTB to fit you right! But why tweak when you get a chance to do the measurements right in the first place.

It is also important because different manufacturers have different standards for their frame sizes. One manufacturer’s large size frame might be a medium one for the other. And this is where everything starts to become complicated.

Let’s find out what the important elements of an MTB and how to measure a mountain bike frame!

Important Elements of Your Bike’s Frame

Here are some important measurements you need to take if you are looking to choose the right bike frame.

When going to your local bike shop, it’s better to take a measuring tape, plumbline, clinometer, and spirit level to take an accurate measurement. You can also download an application on your smartphone if you don’t have a clinometer at disposal.

For the plumbline, you can go for one of those blobs of blue tack and attach a string to it. Bike manufacturers use different units while elaborating on their bikes’ geometry.

For more consistency, it is a good idea to go with the metric units. Just divide centimeters by 2.54 to convert the metrics into inches. You can find the geometrical charts on the manufacturer’s website. These charts can be a good starting point for you for guidance.

Standover: It is the distance between a bike’s top tube and the ground.

Top tube: The length of the top tube is the horizontal distance between the seat post centerline and the head tube centerline.

Seat tube: The length of the seat tube is the distance between the bottom bracket center and the seat tube top.

Reach: Reach concerns about the horizontal distance between these two points, and you will need your spirit level to measure it.

Stack: It is the vertical distance between the two points that we mentioned above.

Wheelbase: The distance between the rear and front axles is called the wheelbase (even on folding mountain bikes).

Chainstay: It is the distance between the bottom bracket axle’s center and the rear dropout center.

Front center: The front center is the length of the chainstay that you can measure from the front dropout to the axle.

Bottom bracket: The drop of the bottom bracket is the distance between the wheel axle height and the crank axle centerline.

Measuring yourself for the perfect fit

The two measurements of your body that you need to take are your head height and the inside leg height, which is also called inseam. To measure your head height, get rid of your shoes, and stand right next to a wall. Now take a small pencil and mark the point where the top of your head is. Then with the help of a measuring tape, measure the distance between the ground and the mark you made on the wall.

To measure your inseam, stand bare feet and measure the length from the crotch seam to the bottom. You can also make a mark on the wall for this like you did when you measured your height. The inseam length will tell you about your standover height, which should have a clearance of at least 1-inch between your inseam and the top tube.

Rider’s HeightInseamRecommended Frame Size
147 cm to 152 cm61 cm to 66 cm47 cm to 48 cm
152 cm to 158 cm64 cm to 69 cm49 cm to 51 cm
158 cm to 163 cm66 cm to 74 cm51 cm to 52 cm
163 cm to 168 cm71 cm to 76 cm52 cm to 53 cm
168 cm to 173 cm74 cm to 74 cm53 cm to 54 cm
173 cm to 178 cm76 cm to 81 cm54 cm to 56 cm
178 cm to 183 cm79 cm to 84 cm56 cm to 58 cm
183 cm to 188 cm81 cm to 86 cm58 cm to 60 cm
188 cm to 193 cm84 cm to 89 cm60 cm to 62 cm
193 cm and above81 cm and above62 cm and above

Get the Measurements Right

Now that you have found out that different measurements go into this entire bike frame measurement process, it’s time to get the number right. There are different methods that you can follow to take the measurements.

But the simplest one of them all is measuring your bike’s seat tube. The direct approach is better because, in most cases, you don’t have much time to get all the measurements that we have mentioned above in a bike shop. It’s just so time-consuming.

You can calculate the suitable bike frame size for yourself by measuring your bike’s seat tube. You can look for the label with the size right at the bottom of your bike’s seat tube for a quick reference. Now start measuring from the gear crank’s center-right to the seat tube top.

As you have measured the inseam before, make sure that you add at least an inch to it to address the matter of clearance. It should be the number that matches the measurement of your bike’s seat tube. It is the ideal way of calculating the right bike frame size for yourself.

Final Word

There you have it, all the information you need on how to measure a mountain bike frame. Once again, we emphasize the fact that you need to get these measurements right if you are looking for a comfortable ride on your MTB. Yes, taking these measurements will consume time, but they will also make sure that you get the most out of your MTB and, of course, your hard-earned money.

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