Water-Bottle "Braze-On" Motor Mounts

Discussion in 'Frame Mounted Engines' started by ahsprite, May 23, 2007.

  1. ahsprite

    ahsprite Guest

    I had a thought about motor mounts. Most everyone seems to use clamps of some kind, and even really nice clamps aren't very elegant (sorry, no offense intended).

    I worked at a bike shop for about a hundred years around a thousand years ago. We had a tool for adding extra water-bottle cage mounts to an existing frame. It worked like a pop-rivet tool. You drilled a hole, inserted the "pop rivet" and the tool compressed it into the hole. A nicely reinforced threaded hole was left behind. Just for giggles, we put one on a wrecked frame and tried to remove it by screwing a bolt half-way in and applying a crow-bar. We destroyed what was left of the seat tube, but it never came out.

    You wouldn't want to do this on a high-dollar thin-walled steel bike, but we did it on a number of run-of-the mill mountain bikes and never had any problems. I believe Cannondale bikes use a similar method for their stock locations.

    If these tools are still around, bolted-in motor mounts (maybe with rubber bushings) might be fairly easy and could look really slick.

    Just a thought.
     

  2. srdavo

    srdavo Active Member

    we use these tools where I work. it pops a 1/4" female thread into square & round tubing. ya got me thinking.....
    thanks
     
  3. Blue Max

    Blue Max Guest

    Hey guys. Call me brave, or maybe crazy, but I just now mounted a 70cc frame motor and used an existing water bottle mount like the one's you describe. No question of it going anywhere, though I'm more concerned about the single 1/4" bolt I am using. I'm installing the Chinese frame motor and the supplier here in Australia calls them "ZBox" engines.

    I've drilled a hole in the center of the curved mounting plate the same size as the mount, so it sits snuggly over and around the bottle mount and on the tube frame, bedded with 1/8" rubber. Tightened down with the 1/4" bolt.

    I have then mounted the engine down onto the backing plate with rubber bushes on the two mounting bolts and more 1'8" rubber between the engine and the plate. So no shortage of rubber.

    It seems very firm and looks like it was made to be that way. Less is more :^D ..Though theoretically there is only that one 1/4" bolt holding the front engine mount to the frame... hopefully I'll fire it up tomorrow...wish me luck.
     
  4. Blue Max

    Blue Max Guest

    Here's a picture of my mount effort. Please guys, don't be shy if you think this is insufficient. I'm really not sure of the shear force involved that would break it. :???:
     

    Attached Files:

  5. Bean Oil

    Bean Oil Guest

    That's a clean way to intall a mount, but no matter the tubing one is still relying only upon a very small portion of the tubing's wall thickness rather than surrounding the entire tube.

    The clamp method is ultimately a much stronger -and- a less likely to fail method of suspending a twisting, vibrating, 20 pound chunk of metal. One must consider long term metals fatigue...


    :)~
     
    Last edited by a moderator: Dec 21, 2007
  6. fetor56

    fetor56 Guest

    Personally i would NOT use this single mounting point idea because i believe it would fail.
    What i did was make an aluminium bracket in the shape of a large cross then bolt the cross to the motor,then bolt the motor to the 2 drink bottle receptors.It works great,just have a rubber mount between the cross and frame.You can also put 2 stainless steel clamps on the upper and lower parts of the cross for additional support and put a small nitch in them to secure each bolt.
    Also if u want a drink bottle put it on the outside of the frame and possibly do as i did,use it as a toolbox.