Rubber mounting tank, engine and tensioner?

Discussion in 'Motorized Bicycle General Discussion' started by meowy84, Aug 29, 2010.

  1. meowy84

    meowy84 New Member

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    I'm sure most of your guys' manuals recommend mounting your engine, tank and tensioner on bits of bicycle inner tube to prevent marring/scratching the paint on your frames. But how many of you guys actually do this? I'm about to assemble my first kit and am trying to figure out which way to go.

    I can see the pros and the cons. The rubber will definitely keep the paint from getting scratched and will also reduce vibration all around. But the mounting won't be as solid as a metal to metal mount.

    FUEL TANK: The fuel tank is no problem since it is fairly light and not the source of vibration or any significant load.

    ENGINE: The engine is another story. Using the stock mounts and some inner tube on the engine mounts I could see how although the vibration transmission will be reduced it is not as solid a mount as using no rubber at all and the engine will have a tendency to be pulled by the chain torque to the left when the bicycle is under power. So what I thought of doing is using the rubber inner tube but also drilling a hole through the U-shaped engine straps and the bicycle frame itself and putting in a screw (a set screw of sorts) to prevent the engine from twisting under torque to the side.

    TENSIONER: With horror stories of the tensioner loosening and jamming itself into the spokes I thought of using the same method as on the engine. Use the rubber inner tube and also drilling a hole for a screw to prevent the tensioner from loosening, twisting on the frame and into the spokes.

    What do you guys think?
     
  2. poo poo pipe

    poo poo pipe New Member

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    Pinning the tensionor.... That is a good idea! would keep it from rotating into the spokes.
     
  3. DudeZXT

    DudeZXT New Member

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    I originally tried mounting an engine with pieces of tire tube between the bike and the mounts and the tensioner and the frame, but everything wasn't secure and moved ~ even almost had a disaster with the tensioner in the spokes, so I took out all the rubber pieces. Didn't notice any difference with vibration and, oh well, the bikes are scratched. I'll just keep the engines on them.

    Only place I'm able to keep rubber is under the gas tank and that's probably actually a good idea, so long as the mounts are tight..

    Oh, yeah, the tensioner: just get rid of it and make your chain the correct length to begin with...
     
  4. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    Rubber- not a good idea except for maybe the tank.
     
  5. meowy84

    meowy84 New Member

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    I will be trying to do this when I finally get around to putting the chain on but sometimes it's just not possible due to frame clearance issues and also since I don't have too much adjustment in the rear wheel it might turn out that my chain will be either too loose or too tight after removing extra links. We'll see though.
     
  6. 2door

    2door Moderator
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    Do not mount the engine with any resilient material (rubber) between the engine and the frame. As has been written here time and again, you are not eliminating vibration but instead transfering it to the engine mounting fasteners which can and probably will fail eventually. Any soft material used to mount the engine or chain tensioner will eventually be worn away and will allow movement resulting in fastener failure or in the case of the tensioner, disaster.
    If you must use rubber use it only under the fuel tank but even then it really does little good. A good quality double sided tape will help keep the fuel tank in place or a bead of silicone adhesive will also prevent it from loosening and rotating on the top tube.
    Tom
     
  7. meowy84

    meowy84 New Member

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    As always thanks to all the MB gurus for the invaluable info. :)

    OK, so rubber = bad idea. But what about the idea of locking or 'pinning' the tensioner and maybe even the engine with a set screw to prevent movement or rotation on the frame tubes?
     
  8. BarelyAWake

    BarelyAWake New Member

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  9. meowy84

    meowy84 New Member

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    Shame on you, selfishly promoting your own thread. LOL j/k

    Seriously thanks for the link. Talk about tensioner overload, no pun intended. Lots of interesting tensioner ideas. I see that right on the first page in one of the pics is my idea of pinning the tensioner as well. I guess great minds think alike.:) lol
     
  10. BarelyAWake

    BarelyAWake New Member

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    Shameless self-promotion! OMG yer right!!1!

    /bans self

    Wait a mo... I'm not tryin' to sell nuffin' lol :D



    BTW, Tom's (2door) is I think really the best, cleanest lookin' solution if ya need a tensioner - or the bolt-on variant if ya can't/don't wanna weld;

    [​IMG]
     
  11. KCvale

    KCvale Active Member

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    Hi, welcome and good luck with your first build!

    Tank:
    I kill two birds with this one.
    I cut off those hard plastic hand grips and use foam ones, but they are longer than I need so with what is left I use it under the tank.

    [​IMG][​IMG]

    Motor Mount:
    Unless your seat tube is too fat for a good fit, don't put anything there other than maybe a little locktight.
    And pinning it won't counter the twist, that is what your front mount is for.
    If it all possible use the dual stud mount so you have a stud on the right side of the front tube, that will counter the twist the best and it is a much longer lever than a pin at the pivot point.

    Tensioner:
    As you read through the myriad of tensioner ideas here you will find one common mantra of mine, if it is at all possible DON'T USE ONE ON THE DRIVE SIDE!

    If chains won't match make the pedal side long and put it there.
    You won't need to worry about rubber or pins or anything, the pedal side is human power and seldom used.
    You don't need to use the big ugly hunk of metal tensioner for the pedal side either, a nice little one like this works just dandy.

    [​IMG]

    All my pedal side needed after getting the motor side right was a single 1/2 link.

    I hope that helps ;-}
     
  12. meowy84

    meowy84 New Member

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    Ah but that's where the true evil genius lies. Advertising/promotion without actually selling anything. :)

    I love the welded tensioner in the pic. Very clean setup without looking like an afterthought. If my frame wasn't already painted I'd go that route. It's hard to anticipate everything on your first build. Will definitely try something like that on my second build.
     
  13. meowy84

    meowy84 New Member

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    Thanks for the encouragement and especially the tips. This first build has been over a year in the works mostly because of work/family obligations.

    Anyways, I know you mentioned that the front mount helps with the twist of the engine but I like the thought of a properly triangulated mount setup. That would obviously work the best. Two mounting points can work very well if you weld in solid mounting brackets onto the frame. With the stock straps i would think there's always a fair potential for twist unless you do the nuts up really, really tight in which case you run the risk of pulling the studs out of the case. I love your idea of the tensioner on the pedal chain though since unless all the planets are in perfect alignment and you luck out you're bound to end up with one of the chains either too loose or too tight especially if not running a derailleur to take up the slack on the bicycle chain.
     
    #13 meowy84, Sep 3, 2010
    Last edited: Sep 3, 2010

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