3 speed hub

Discussion in '2-Stroke Engines' started by jtbarnes89, Sep 9, 2010.

  1. jtbarnes89

    jtbarnes89 Member

    i am just wondering if anyone has ever done a 3 speed rear hub on a motorized bike??? im wondering if it is strong enough to handle the torque.. i used to have a tall bike with one and it seemed pretty strong but idk
     

  2. SimpleSimon

    SimpleSimon Active Member

    To answer your questions - yes, and yes.

    The multi-speed internal shifting hubs are engineered for much higher stresses than any small engine is going to put on them. The only real issue is with the 7,8 or higher number of gears hubs and vibration transmitted through the chain line from the engine. The higher the number of gears, the thinner the internal discs in the hub. Vibration on the very thin discs can start slipping.
     
  3. jtbarnes89

    jtbarnes89 Member

    wat would be a good size that wont slip?? i have a 26 inch cruiser with a 66cc grubbee with a 36 tooth rear sprocket
     
  4. SimpleSimon

    SimpleSimon Active Member

    Well, let me ask - are you proposing to add a jackshaft and combine the pedal side and power run in one chain loop? If so, I'd recommend the Sick Bike Parts jackshaft kit, and whatever internal hub you want to use. Properly installed, the jackshaft should isolate the worst of the vibration pretty well, and the rear multi-speed huib will simply function as normal.
     
  5. skrufryder

    skrufryder Member

    i'm looking for a 5-7 internal hub with disc brake anyone ever see one?????
     
  6. jtbarnes89

    jtbarnes89 Member

    well if i do that then i wouldnt be able to pedal and 2nd i would just go with a regular shift if i did that.. the reason i want the internal hub is to be able to shift gears and have a sprocket mounted one one side and a free spin hub to peddle with on the other
     
  7. HeadSmess

    HeadSmess Well-Known Member

    ive been pondering the thing for a while...

    problem with hubs for pushies is the drive is on the right, and for a gear shift to work solely on the engine...it would need to be on the left... i havent bothered checking but im assuming these "shift kits" are a jackshaft that then drives the cranks...yuk. the idea just sounds horrible.

    on the other hand...if you got a shift kit,and drove the 3 speed hub directly, with a free wheel mounted on the left hand side for pedalling (like some bmx bikes now have the chains on the left!) it would be fairly simple, with only the need for a thread to be machined on the hub to take the left hand freewheel...


    then...how do you start? theres a freewheel there! in the 3speed hub!

    (ive thought of that too...a recoil spring starter? roll back a bit, then...yeah)

    work out how to actually pull one apart and jam its pawls up so it cant freewheel :)

    im gunna do this now... :) and do i have the bike?
    oh yeah !
    but iunno.

    ive been told that gear hubs dont take too much torque at all... and ive found a few old ones that have obviously chewed out...shimano suntour, sturmey archers...etc...and not from motors, id say...
     
    Last edited: Sep 11, 2010
  8. HeadSmess

    HeadSmess Well-Known Member

    and note that with gear hubs...you are meant to stop pedalling briefly when shifting...unlike them brutal derailleur setups...

    you may want to use the clutch on the shifts...
     
  9. Ghost0

    Ghost0 Guest

    Lots of our customers have used internal hubs with mostly good success. They tend to fail if they are not adjusted correctly or if abused during shifting.
     
  10. jtbarnes89

    jtbarnes89 Member

    im gonna do it but where i live no shop will sell the three speed hub or wheel.. so im going to have to find a used one and true the wheel and grease it and keep the one i have now for a spare incase i destroy the three speed
     
  11. HeadSmess

    HeadSmess Well-Known Member

    ive done the research.

    its possible to drive the 3speed independent of the pedals.

    first. shimano suntour has enough meat on the left hand side to machine a thread to take a "southpaw" sprocket. no way to jam any of its 4 freewheels without ending up with a single speed again though...

    so...starting?

    there are things called 1-way bearings. ie, freewheels... or sprag clutches? anyone into RC cars will know what they are. (just a bit bigger)

    one of these, and a strong "clock" spring on the crank...

    push it BACKWARDS, winding the spring... pull in clutch. engine will start :)

    will have to mod the pinion retaining screw with stub to take the bearing....and think of a way to lock it.

    all simple things with a lathe :)
     
  12. jtbarnes89

    jtbarnes89 Member

    im not sure if u understand the question.. i was simply just swaping to a 3 speed rear hub and mounting my sproket on the spokes
     
  13. jtbarnes89

    jtbarnes89 Member

    good info thank you
     
  14. HeadSmess

    HeadSmess Well-Known Member

    :lol: tis cool. i took the idea and ran away with it...

    mmmmm, 3 speed engine... and i like tinkering :)
     
  15. jtbarnes89

    jtbarnes89 Member

    so do i but i think after all im gonna go will a single gear for pedaling and a coaster brake and a 27 tooth mounted on the spokes for the motor
     
  16. Whizzerd

    Whizzerd Member

    Guys, it's been often posted that the S-RAM I model geared hub is beefy enough for mb use. Anything on these mb's that's abused will fail. The SickBikeParts shift-kit is highly praised by users and has a freewheel designed into the unit.
     
  17. jtbarnes89

    jtbarnes89 Member

    ive been saying this the whole time.. im not interested in a shift kit or a jackshaft.. this is about a internal shift.. please stay on topic.. ur idea may be good but it has been offered houndreds of times
     
  18. Whizzerd

    Whizzerd Member

    My apologies, young man, good luck with your quest.
     
  19. HeadSmess

    HeadSmess Well-Known Member

    yes. what you asked was. "can i put a sprocket on a motored bike that has a 3 speed hub instead of a derailleur change" (basically)

    a bleedingly obvious answer really...why not? a bike wheel is a bike wheel is a bike wheel is a bike wheel is a bike wheel and if i could ride a unicycle, id sure as **** put one onto its wheel as well....

    the only problem you may have is its a 28 0r 32 spoke wheel which needs different holes in the sprocket.

    what i proposed was abusing a 3 speed way beyond its intended design :D

    for you? pedalling? why even ask? thats what they are designed for, strangely. pedalling.

    to the hub, being driven through the spokes is no different to rolling down a hill coasting.... or using the brakes (rim mounted)

    right. next silly question :)
     
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