Can I use a Chromoly bike frame?

Discussion in 'Motorized Bicycle General Discussion' started by J0sh, Jan 16, 2014.

  1. J0sh

    J0sh New Member

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    Hey guys I was thinking about getting a Univega Rover 3.5 Mountain Bike with an XL frame but I think the frame is made of Chromoly, can I use that with the motor or will the vibrations break it? I need some insight on this as soon as possible please (Sorry if it is ovbious I don't know anything)
    Picture of the bikes and some specs below
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    (Right click on the little boxes then click open in new tab see picture)
     
    #1 J0sh, Jan 16, 2014
    Last edited: Jan 16, 2014
  2. bluegoatwoods

    bluegoatwoods Active Member

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    I think chromoly is one of the best frame materials for this job.

    But I'm no expert. If I'm missing something, though, some one who knows more about it will correct me.

    Still, I think a chromoly frame will get a whole bunch of 'thumbs up'.
     
  3. wheelbender6

    wheelbender6 Active Member

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    Chromoly is a good frame material for motorizing. However, I motorized a nice chromoly framed bike and found the vibration and ride quality to be pretty harsh, compared to a frame with tensile steel (tensile is used in inexpensive bikes). Maybe its just me.
    Yes, chromo is great for motorizing. Just be prepared to swap to a tensile steel frame if you can't ride under power comfortably.
     
  4. oldtimer54

    oldtimer54 Member

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    I use it when I can. I think its the best you can get.
     
  5. 2door

    2door Moderator
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    Just a word of caution:
    If you plan to do any welding on a chrome moly steel frame, make sure the welder knows what he's doing. It takes a little more skill to do it right.
    Chromium-molybnium steel is an alloy with some heat treating involved. It can be welded but the welder neeeds to be proficient at the process.

    Tom
     
  6. maniac57

    maniac57 Old, Fat, and still faster than you

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    Minor welding like tacking the tensioner is okay, but as 2door stated, structural welds need to be done by an experienced welder, preferably with TIG since it requires far less total heat input and is much less likely to affect heat treating.
    NHRA Drag racing rules require TIG to be used on any chromoly roll bar work.
    I also agree with wheelbender about chromoly frames being harsher. The stiffness of the material transmits vibration more than mild steel and much more than aluminum.
    Some people notice it, some don't. I love a stiff frame from my racing days but I must admit a buzzy engine might make them uncomfortable if you are sensitive enough to notice the difference.
     

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