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Framebuilders Thinking about a custom frame? Lugged vs Fillet Brazed. Different Frame materials? Newvex or Pacenti Lugs? why get a custom Road, Mountain, or Track Frame? Got a question about framebuilding? Lets discuss framebuilding at it's finest.

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Old 12-15-05, 11:01 AM   #1
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What seatpost angle is best?

If you want to put aero bars on your bike, do you make sure the seat angle is about 75..76 degrees or not?
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Old 12-15-05, 12:27 PM   #2
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i believe you're refering to the seat tube angle and not the seat angle. the Seat angle is always level or parallel to the ground. With the exception of a brand new Brooks Leather saddle, i always tip the nose down the tinest bit(2-4mm).This helps to relieve pressure on a new saddle.
Now for frame building, look at detailed photos of bikes that you want to pattern your frame after and measure the angle of the seat tube in the photo. Aero bars are used primarily for timetrails and ironman style triathelons. Look made a nice time trial bike with aerobars and the seat tube looked to me to be closer to a 74.5 or 75. Keep in mind that the body is shifted forward almost in front of the crank.
Check out the different bike companys frame geometry spec's.
good luck
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Old 12-15-05, 02:01 PM   #3
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Quote:
Originally Posted by king koeller
i believe you're refering to the seat tube angle and not the seat angle.
You're correct, unfortunately I don't know how to change the subject line of a thread.

Question still is: if using full length aero bars, then does the 75-77 seat tube angle allow proper breathing, ala,
Tri bike, vs 72-73 of road bike.
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Old 12-15-05, 02:17 PM   #4
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I fixed the title for you.
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Old 12-15-05, 04:08 PM   #5
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thanks lala
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Old 12-16-05, 01:43 AM   #6
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there is just so many other factors to consider....
1. top tube length.
2. Saddle fore and aft adjustment...
3. stem extention and rise of your aero bars
4, height of saddle...
5. wheel base of overall frame and fork...
This is why i love all bicycles, so many factors and possibilitys!
Good luck!
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Old 12-16-05, 10:36 AM   #7
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why? I would think all that matters is:

1. seat tube angle
2. height of seat vs height of bars

Others will effect how the bike rides, but not how you feel when pedaling in a more laid out position.
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Old 12-18-05, 10:02 PM   #8
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Quote:
Originally Posted by HiYoSilver
why? I would think all that matters is:

1. seat tube angle
2. height of seat vs height of bars

Others will effect how the bike rides, but not how you feel when pedaling in a more laid out position.
Actually, they make bizarre "Tri seatposts" intended specifically for use with aero bars. If the seat tube angle isn't upright enough to provide proper fit and extension over the bike, the tri-seatpost has a forward-set seat clamp!

This forward-set clamp moves the rider forward over the frame, allowing a variety of fit adjustments. Looks strange, but it obviously makes sense for aerobar/triathlon use.

Ideally, you're right - the seat tube angle should be significantly more upright than a standard road bike to facilitate proper fit with a torso-forward, aerodynamic posture. Same with bar height vs. seat height, but obviously, some adjustments are still required.
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