Parts of a Bicycle: Part 2 - The Frame

We saw from Part 1 what a bike is and the four major component groups. In this article, we will be talking about the first - the Frame. The frame is the skeleton of the bike. It is where all the other components are attached. The frame set includes the fork which holds the front wheel in place and allows steering the bike.

The frame and the fork comprise the skeleton of the bike.

Triangles.
A frame has seemingly three triangles.

The Front Triangle.

There are one Front Triangle and two Rear Triangles. The Front Triangle seems to be "triangle" but it has four sides. The tubes are the Seat tube, Down tube, Top tube and Head tube.

1. The Head Tube holds the fork in place.

2. The Seat Tube is for the seatpost that mounts the seat/saddle. Some frames have the seatpost integrated with the seat tube. Moreover, the seat tube length defines the height of the frame and frame sizes are normally defined by the length of the seat tube.

3. The Top Tube defines the length of the frame for its rider. If its too long, the rider is stretched and if it is too short, then the rider will be cramped up.

4. The Down Tube provides support for the frame. It also counteracts the force created when pedaling. 

The Rear Triangles.

The Rear Triangles are two triangles created by the Seat tube, the Chain stays and the Seat stays. The rear triangle holds the rear wheel in place.
1. The Chain Stays are a pair of tubes that run parallel to the chain of the bike. These provide the support for the forces acting on the rear wheel.
2. The Seat Stays are also a pair of tubes. These are attached on the end of the chain stays and seat tube. These provide support for the rider's weight.


Bottom Bracket Shell. The Bottom Bracket (BB) shell is where the bottom bracket and the cranks attach on to the frame. There are different types of bottom bracket shells with different diameters and lengths. Most are threaded but there are also smooth bottom bracket shells for "Pressfit" bottom brackets. For threaded bottom brackets, the bearings for the crank are threaded/screwed unto the frame. For the Pressfit types, as the name suggests, the bearings are pressed unto the frame.


Drive-side vs Non-drive-side. This is the left and right sides of the bicycle frame. The Drive-side is the right side of the bike. It is called the "Drive-side" because it is where the drive or the force is - where the crank, cogs and chain are. The left side is called the Non-drive-side because it is on the opposite side - the side without the drive.

The side of the bike's mechanisms is called the Drive-side.

I hope you learned a lot about the different parts of a bicycle frame. Remember the names of the tubes and these can help you find the perfect size for your next bike.

Please stay tuned. Next up is Part 3 - The Wheels.


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