cranbrook frame weakness, pried a wide wheel into it

Discussion in 'Motorized Bicycle General Discussion' started by tire, Oct 13, 2010.

  1. tire

    tire New Member

    Joined:
    Sep 29, 2010
    Messages:
    121
    Likes Received:
    0
    i pried a mountain bike wheel that was about 1/2 - 3/4" wider than the original wheel into my cranbrook. i was reading the "how to beef up my cruiser" thread and someone mentioned the weakest part of the frame being the wheel attachment points (welds, "hook", or whatever other term was used). since i, in all my wisdom, assumed that the frame was plenty strong and pried it apart, will this probably weaken the frame and lead to Oh-****-My-Rear-Wheel-Fell-Off-While-Going-25mph?

    i don't see any cracks on the rear fork near the wheel attachment nor the welds securing the rear forks to the main frame tubing.

    austin
     
  2. Kevlarr

    Kevlarr New Member

    Joined:
    Jul 22, 2009
    Messages:
    1,628
    Likes Received:
    0
    The weak point in a Cranbrook is in the seatstays where they attach to the top tube.
    [​IMG]
    [​IMG]
     
    #2 Kevlarr, Oct 13, 2010
    Last edited: Oct 13, 2010
  3. tire

    tire New Member

    Joined:
    Sep 29, 2010
    Messages:
    121
    Likes Received:
    0
    as in one's seat may just fall off one day? that would be pretty funny to see provided no one got too badly injured.

    recommendations? i can weld it thicker around the bottom, would that suffice?
     
  4. tire

    tire New Member

    Joined:
    Sep 29, 2010
    Messages:
    121
    Likes Received:
    0
    what am i supposed to notice? i see a u-bolt but that looks like it is there to secure a rear rack or something. or are you just showing me the bracket that fails... where the lever twists to secure the seat post?
     
  5. Kevlarr

    Kevlarr New Member

    Joined:
    Jul 22, 2009
    Messages:
    1,628
    Likes Received:
    0
    There is no real fix for his problem because if you make it stronger by the seat tube the stays will just crack further back by the crossbar.
     
  6. Kevlarr

    Kevlarr New Member

    Joined:
    Jul 22, 2009
    Messages:
    1,628
    Likes Received:
    0
    Notice the cracks in the seatstays just before the seat tube.
     
  7. Kevlarr

    Kevlarr New Member

    Joined:
    Jul 22, 2009
    Messages:
    1,628
    Likes Received:
    0
  8. tire

    tire New Member

    Joined:
    Sep 29, 2010
    Messages:
    121
    Likes Received:
    0
    oh, i see it now, it is in front of the white wire on the cantilever bar just forward of the zip tie?

    how does the full suspension ride? i wouldn't do anything like that because i already put a front suspension on it which is fine by me. not sure what i'd do, but i won't be happy.

    would welding in a straight medium thickness bar between the seat post and front post bypass the stress on the thin cantilever bars and prevent a break?
     

Share This Page