Anatomy of a bicycle, #2

Good afternoon.

Returning to the cycling theme, the bike-building will be starting soon, as I've just ordered my frame! After reading Robert Penn's "It's All About The Bike", I opted to go for a steel frame. A custom-fitted, hand-built Rourke frame is (ahem) slightly outside my budget, so instead I'm going for a Genesis Equilibrium 56cm frame. It's within my budget, I've read some rave reviews of it, and it's the bike of choice for the mechanics at a couple of local bike shops, so I think it'll be a good starting point.

[Aside: This will be the first time in about 20 years that I've had a steel-frame bike. The last one was a wonderful chromoly Peugeot BMX that I had up until I was about 13. After that, I went without a bike at all for the best part of 10 years. I often wonder what I could have done in that 10 years I was lost to cycling.]

So, that's the frame - a series of tubes welded together, in a roughly diamond shape. The best diagram I've found to explain the geometry of a frame is this one, which just happens to be annotated in Japanese:

• Top tube (トップチューブ): The topmost, horizontal tube, which runs from where the saddle would be to where the handlebars go.
• Seat tube (シートチューブ): The tube which goes down from where the saddle would be to where the pedals are.
• Head tube (ヘッドチューブ): The small tube at the front.
• Down tube (ダウンチューブ): The tube which runs diagonally from the bottom of the head tube to where the pedals are.
• Seat stays (シートステイ): The two tubes which run diagonally from where the saddle would be to where the back wheel is attached.
• Chain stays (チェーンステイ): The two tubes which run (almost) horizontally from where the pedals are to where the back wheel is attached.

Also annotated on this diagram is the fork, the steerable bit at the front which runs through the head tube and to which the front wheel is attached.

My first assembly job is coming up soon ... fitting the fork and the frame together, which requires me to read up on and familiarise myself with headsets. Expect to read something about them in the near future!