Advertise on Bikeforums.net



User Tag List

Results 1 to 6 of 6

Thread: Main Triangle

  1. #1
    Member
    Join Date
    Apr 2008
    Posts
    37
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Main Triangle

    Am I correct to assume that the four inside angles of the main triangle should sum to 360 degrees? Mathematically this is tru for a four-side polygon but I'm wondering if frame builders deviate (by say 1 degrees) for some reason I'm not aware of.

    Thanks

  2. #2
    Senior Member
    Join Date
    Sep 2005
    Posts
    4,757
    Mentioned
    6 Post(s)
    Tagged
    0 Thread(s)
    The sum of the interior angels of a quadrangle is always 360, there is no way around it.
    180 (n-2) where n is the number of sides of the polygon.
    You could put a bend in one of the pipes to make up for it, but I have not worked with metal and don't know if there is a reason one would want to do such.

  3. #3
    Member
    Join Date
    Apr 2008
    Posts
    37
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Thanks.

    The specs provided to me by a lug maker don't sum to 360. I'll request they re-submit specs on assumption they made an error.

  4. #4
    Senior Member
    Join Date
    Sep 2005
    Posts
    4,757
    Mentioned
    6 Post(s)
    Tagged
    0 Thread(s)
    Ask again at Frameforum.net.
    They have more traffic from professional frame builders, and you'll get a more informed answer.

  5. #5
    Framebuilder
    Join Date
    Dec 2007
    Posts
    485
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Hi,
    Are you talking about adding up the lug angles from the ht/st/bb? Most lug angles are measured in relation to an imaginary vertical plane and can vary according to the design ie: road bike, track bike, amount of bb drop, sloping top tubes.....there is no reason the angles should add up to 360.

  6. #6
    Member
    Join Date
    Apr 2008
    Posts
    37
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    These are the angles I summed:
    st/tt + tt/ht + ht/dt + dt/bb/st

    tt/ht is actually 180 minus tt/ht

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •