making a trike

Discussion in 'Motorized Trikes' started by motor_head, Feb 1, 2010.

  1. motor_head

    motor_head Member

    well i decided i want to motorize a trike mainly for cargo space and because of how easy it will be to make a drivetrain for it with a briggs.

    so i can't find any cheap trikes so i thought why not make one, i mean use a regular bike and just weld up a frame so it will have a platform. any ideas on how wide, i was thinking somewhere around 3' wide i want it to be fairly stable and i don't have any experiece with trikes.

    for the axel i want 2 wheel drive so it doesn't pull to one side when exelerating, but then i need a diff, i was thinking take apart a lawnmower transaxel and use the diff but i will have to see what the thing looks like maybe it won't even work.

    also want to use the five speed hub heres a drawing of what i was thinking, yes i know no pedals but i live in iowa and am going to register as moped

    Attached Files:

  2. SimpleSimon

    SimpleSimon Active Member

    There are a number of sources for prebuilt, well engineered trike conversion units out there. One of the sponsors here, SpookyTooth, sells one.

    As for powering both wheels with a "differential" there are various options, but here's what I would recommend, and it is in fact what I have done with a trike conversion I am working on. Use your multi-speed hub as a "mid-drive", and get a pair of sprockets made to bolt onto the spoke flanges on each side of it. From each of those sprockets a chain loop goes to a freewheel capable sprocket on the inside ends of each half axle (most trike conversions are solid axle, designed to power only one wheel, usually the right). I paid a machine shop to clean up the rather rough cut I made dividing the axle into two halves, cut a keyway into each internal half axle end for the freewheel sprockets, and key the outer end of the left side half axle and make a drive flange for it

    As you corner your outside wheel is going to need to turn faster than the inside wheel, and by incorporating freewheel chain sprockets as I've said, the axle is free to turn in the sprocket, yet when the sprocket is pulling on the straight stretches, the power goes evenly to both half axles. Voila - differential effect.

    I am using a Shimano internally geared three speed hub. I would NOT recommend anything more than a seven speed - as the number of gear ratios increases the internal discs of the hub get thinner and more subject to breakage under high torque loads.

    I would also advise that you check your state laws carefully - most "moped" category rides must have an automatic transmission
  3. motor_head

    motor_head Member

    here's what it says
    "New Moped Definition

    A "motorized bicycle," or moped, is motor vehicle having a saddle or a seat for the use of a rider, designed to travel on not more than three wheels in contact with the ground, and not capable of operating at a speed in excess of 30 miles per hour on level ground unassisted by human power. The maximum speed of 30mph needs to be printed on the certificate of origin from the manufacturer.

    The new definition for a moped written above replaces the reference to "an engine having a displacement of no greater than 50c.c." The change in the definition allows electric motors or electric engines to be used as a source for moped propulsion.

    Additionally, for a moped to be classified as a motor vehicle, it must be able to travel at a speed of atleast 20mph while driving up a 3 percent grade. If a vehicle cannot go 20mph up a 3 percent grade, it is not permitted to be operated on Iowa's streets and roadways"

    yes i know a 3hp briggs is over 50cc

    my thought for the axle was a differential taken out of a lawn mower transaxle with a bike sprocket, and mount it to some new bearings and use that for the diff. i don't know if it will work but once the snow melts i can go look at it and try to pull out the diff

    I think i can weld up a frame i have metal so it would be almost free, I don't really want to buy a kit