This question is concerned with the minimum frame size required for link layer c

Question

This question is concerned with the minimum frame size required for link layer collision detection on a shared broadcast channel such as Ethernet protocol with shared bus topology. For example, 10Base Ethernet imposes a minimum frame size of 64 bytes. Suppose that two nodes A and B are connected together using a broadcast channel such that: - distance between A and B is d meters,  - signals propagate in the channel at the speed of c meters per second, - transmission speed of the channel is R bits per second. Suppose that node A begins transmitting a frame, and before it finishes, node B begins transmitting a frame. If the frame size is too small then A may finish transmitting before it detects that B has transmitted. Derive a formula to find the minimum size needed for a link layer frame in this network in order to correctly detect collisions.

Explanation / Answer

How much seat post is showing depends on the geometry of your bike. If you have a classic geometry frame with a horizontal top tube, there will be less seatpost showing. If you have a compact frame geometry with a sloping top tube you will have more seatpost showing. How much is too much? Well depends on what king of riding you do. If you want a more comfortable, relaxed riding you want to be able to lower the seatpost to the point where the saddle is about the same height as the handlebars. If you cannot lower the seatpost that much or raise the handlebar that high then you might want a different frame size. If you want a more aggressive racing position then you want the saddle to be about 3 to 5 inches higher than the handlebar. (Don't go to 5 inches unless you are limber and flexible enough or it will do a number on your back!) Again, if you cannot reach these goals then you might want a different frame size. There are a lot of other things that factor into frame size. You asked only about seatpost position so I have constrained my answer to that... Best answer though is to go to your LBS and have them help you if you are in doubt.

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