Seat tube angles
12-30-06, 02:49 PM
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Seat tube angles
I have read that the "proper" riding position in relation to seat fore and aft position is that with a plumb line, the front of the knee should be in-line with the bottom bracket spindle. Now with this in mind, I notice that many TT and Tri bikes have a steeper seat tube angle to move the rider more forward on the bike. How can the knee/spindle be achieved with such a steep angle?
12-30-06, 04:25 PM
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They don't acheive the knee/spindle (KOPS) on TT/TRI bikes. They are infront of it. These bikes use TT/TRI handlbars however and they are NOT used for mass start races so they weight on your hands and handling issues aren't so important. The advantage of this setup is that it opens up the hip angles and makes it easier to adopt an aero position for a long period of time when used in conjunction with aero bars. Its not a good position however for general road riding.
Regards, Anthony
Regards, Anthony
12-31-06, 09:40 AM
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Originally Posted by bfloyd
I have read that the "proper" riding position in relation to seat fore and aft position is that with a plumb line, the front of the knee should be in-line with the bottom bracket spindle. Now with this in mind, I notice that many TT and Tri bikes have a steeper seat tube angle to move the rider more forward on the bike. How can the knee/spindle be achieved with such a steep angle?
12-31-06, 10:01 AM
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TT and tri bikes aren't made for regular riding, they're made for raceing.
Try to picture in your mind a rider on a conventional road frame. Now keeping relative angles of the rider's body constant, imagine rotating it so that the head and shoulders are lower. The butt moves forward relative to the feet. That's tri geometry. Uh - Unless you have a pretty flexible neck you aren't going to be able to see where you are going very well.
Try to picture in your mind a rider on a conventional road frame. Now keeping relative angles of the rider's body constant, imagine rotating it so that the head and shoulders are lower. The butt moves forward relative to the feet. That's tri geometry. Uh - Unless you have a pretty flexible neck you aren't going to be able to see where you are going very well.
