Fronkenstien GB5 Powered trike

Discussion in 'Motorized Trikes' started by tbrookes2000, May 27, 2011.


What can I do different or more effectively?

  1. steering type or configuration

    1 vote(s)
  2. frame configuration

    2 vote(s)
  3. Lighting

    1 vote(s)
  4. Wheels and Tires

    0 vote(s)
Multiple votes are allowed.
  1. tbrookes2000

    tbrookes2000 New Member

    Hi guys..
    I was told to post my next posting here so here is an update on Fronkenstien
    Newly added today are the monstrous steering knuckle, front crank, and a
    1" x 1/4" flatbar stiffener under the main rail. I'm happy to be here...I have seen the trikes in this forum and there are some very cool machines here. Happy to be in their company. Let me know what you think of my monstrosity. I hope to have it completed in the next few, lights, paint, and "tweaking" still to go. Have a fun, and SAFE holiday weekend!

    Attached Files:

  2. a/c man

    a/c man Member

    Very cool bike.
    Kind of like dreaming out loud.
    Looks like you have some skills and and a good imagination.
    I'll be following this one for sure.
    What will you be powering this monster with?
    Looks like a good candidate for a HF 4 stroker.
    Good job so far, keep up the pictures.
  3. SimpleSimon

    SimpleSimon Active Member

    Overall, I like it.

    I'm a bit concerned about strength of materials issues on that main boom - it looks really light for the potential loading. Also, may I ask why you did not apply Ackerman steering geometry? Eyeball guesstimating that build, it looks like you need at least a nine degree rake, which doesn't appear to be there - without it, steering scrub is going to be a problem. Not too mention zero-point camber geometry for the kingpins.
  4. srdavo

    srdavo Active Member

    I agree.

    That's some mighty pretty welding!!! :tt1:
    As for strength.... the 1" x 1/4" flatbar stiffener will add a lot!!

    Looks to me, He will gain some rake, once he's seated on the trike & the rear suspension settles a little.

    As for camber.... I'd like to see a pic of this, straight on, frame level, from front to back.

    Looking Good!!!! Keep us updated!!
  5. tbrookes2000

    tbrookes2000 New Member

    Input welcomed!

    Hi all!
    Well, I HAVE looked up the Ackerman principles, but I'm not so sure I understand what they are telling me. Any help in this area will be greatly appreciated. Thanks for all the compliments. I have the "picture" of what I want in my head, and I've kinda just been going with what I thought was appropriate...which is the reason for the "go cart" steering (Yeah, I don't know any better) So in this respect, I shall need all the ideas and help to put it all right. As for the strength...I HAVE sat uopn it (I weight 178# with a candy bar in my pocket) and it's plenty strong...also...the 1 x 1 spine goes all the way into the body tube in the back with stiffeners inside the tube to disperse the load. Not sure just HOW much rake I'll get once on it, but I have to say that the steering part of this project has been the most perplexing...So how to I do it to make it better. The steering as present is 1/2" kingpins...where do I go from here?
    It all is all designed to be powered by my Grubee GT5 engine.
    I'll be looking forward to the help...
  6. nice work looking good :cool2:
  7. SimpleSimon

    SimpleSimon Active Member

    tb2000 (and anyone interested), I'd suggest that you study the Trike Steering Geometry tutorial posted at the linked site. It is very clearly written, uses minimal technical terms.

    Read it over, study the diagrams, and think about the forces applied when the trike is rolling - visualize yourself in the seat and you'll see why the various geometric rules apply, and how they work to stabilize steering, reduce scrub, and neutralize shock forces twisting the steering in your hands.
    Last edited: May 29, 2011
  8. Big Red

    Big Red Active Member

    Three wheelers

    Hey tbrookes2000,
    I had the same idea about 2 years ago. I'm kinda lazy so I took the easy way out. I took a standard go-cart frame, Removed the rear wheels & axle, Cut the front steering off a goped, bolted it to the back and added a peddle system. I used bicycle equipment such as front wheels and handlebars ect. to convince the cops that it's a 3 wheeled, recumbent motorized bicycle.
    I checked out California law to make sure I complied, (that's where I live) and so far I've had no problems. Of course it's not a racer, It's top speed is about 22mph but that's fast enough for as low to the ground it sets.
    Your's looks much COOLER and I wish you the very best on your build.
    Big Red.