Getting the right size of bike can make or break your safety on the road. No matter how skillful you are in riding, you're still vulnerable to accidents if you don't have the appropriate bike.

This is why it's essential to know the proper measurement of bikes before getting a new one. This way, you can ensure safety and convenience in every ride.

How to measure the bike size

There are several things that you have to consider in getting the right size of bikes. These are: 

1. Top tube length
2. Seat tube length
3. Reach and stack
4. Wheelbase
5. Chainstay length
6. Front center
7. Seat tube and head tube angles
8. Bottom bracket

Each of these parts should be proportionate to the user's body size to ensure comfort and safety. Here are some ways on how to accurately measure each of the parts of a bike. 

Top tube length

The actual top-tube length will often be listed in a bike geometry table. The horizontal top tube length, also known as the effective top tube length or top tube in many geo charts, must be measured for a reliable measurement, independent of the top tube angle. 

That is the horizontal separation between the seat post centerline and the head tube centerline. You must use your spirit level or the clinometer app to confirm that your measurement is horizontal.

Seat tube length

The seat tube length is measured from the bottom bracket's center to the point where the top tube and seat tube converge (Centre-Centre or C-C) or from the center of the seat tube to its top (Centre-Top or C-T). 

Similar to stack, the term "effective seat tube length" describes the distance from the center of the bottom bracket to the point where a top tube that was virtually horizontal would meet the seat tube.

Reach and stack

The stack is the vertical space between the centers of the headtube's top and bottom brackets. Reach measures the distance horizontally between the centers of the bottom bracket and the top of the headtube. 

This information provides the bike's frame stack and reach, the most typical measurement mentioned when discussing stack and reach. By measuring to the center of the top of the handlebar, you can account for any external headset cups, cone spacers, and steerer spacers, as well as stem length and angle.

Wheelbase

The distance between the centers of the bike's front and rear axles is known as the wheelbase. 

A bicycle's wheelbase is calculated from the front axle's center to the rear axle's center. It is one of the essential metrics of bike geometry and is frequently mentioned as a tool to gauge how well a bike will perform in terms of steering speed, responsiveness, and stability.

Chainstay length

The separation between the bottom brackets and the rear wheel axle's centers. The width of the bottom bracket is not taken into account because this measurement is made from the side perspective of the bicycle and ignores the z-axis. Enter the shortest length for horizontal, sliding, or rocker dropouts. 

The handling of a bike can be significantly impacted by chainstay length.

Front center

The distance between the front wheel axle's center and the bottom bracket's center. The width of the axle or bottom frame is not considered because this measurement is made from the side perspective of the bicycle and ignores the z-axis.

Seat tube and head tube angles

It is an angle measured from horizontal to a line drawn from the bottom bracket's center up to the point where the seat tube's actual angle intersects the top of the head tube. Actual and virtual seat angles are calculated from the head tube's top.