Clutch on vintage bikes?

Discussion in 'Antique Motorized Bicycles' started by steamtrac, Dec 16, 2008.

  1. steamtrac

    steamtrac New Member


    I am a model engineering enthusiast, and getting now in love with motorised bikes ;-)
    Next project will be to adapt one of my engines into a bicycle frame. It will be a 90cc 4 stroke engine.
    Clear up to now is, that the "drive train" will be a belt to the rear wheel, with the beautiful big pullys on the rear wheel, like many vintage bikes have. What is missing at the moment is a good idea for the clutch. I don't want to use a centrifugal clutch, it has to operated by a lever or handle.

    Does anbody of you vintage guys has a good idea for the clutch? Maybe some of you can provide photos? That would be great. I love the "open design", where you can see all the parts moving. I thank you very much for the support.


    RATRODER Guest

    steamtrac here is just one, I'll see if I can dig up some more. louis

    Attached Files:

  3. steamtrac

    steamtrac New Member

    Whow, that bike is really nice looking.
    But what kind of clutch does this one have??
  4. srdavo

    srdavo Active Member

    it has an idler pulley that tightens & loosens the belt tension. no clutch.

    RATRODER Guest

    Attached Files:

  6. I have built about 14 or 15 motorbikes and most of them used an idler pulley on the backside of the belt on the bottom run to tension it. I generally use a motorcycle clutch or brake lever and also provide a peddle on the idler arm so I can hold it disengaged for starting by pull rope. The spring is usually a trampoline or spriing horse spring. The idler pulley is a flat one with ball bearings. They should be obtainable at a lawn mower shop. If not a good pulley and sprocket stockist can supply. All but the Chinese 2-stroke have footboards and no peddles. See my artical." BUILDING A PRACTICAL AND SAFE MOTORBIKE." If you wish, send your email address to and I will send you a picture offline since I haven't mastered the art of sending coded pix here.:whistling:
  7. steamtrac

    steamtrac New Member

    Hi William,

    I would love to see your bikes, I will send you my email adress later.
    Thank you for your memomries in the other thread, it really made me laught and smile. Must have been an exciting time with your innovative transportation vehicles!!
  8. Esteban

    Esteban Active Member

    Many riding lawnmowers, garden tractors , etc., have used the same type system. The older Snapper rear engine mowers used this system to disengage their clutch [ to stop the cutting blade. ]