GiantStone MB-Iguana

Discussion in 'Frame Mounted Engines' started by ocscully, Nov 9, 2007.

  1. ocscully

    ocscully Member

    This is the start of a build thread for my first motored bicycle. The frame shown is a composite of two different bikes. The top tube, head tube, down tube, forward bb-shell and fork are from an early 90's Giant Iguana and the rear triangle, seat tube, seat stays, chain stays, and back bb-shell are from a 92 Bridgstone MB-4. The motor is a Honda GXH50. The final drivetrain has not been fully fleshed out but I'm currently envisioning a primary belt drive to a jackshaft and a secondary belt drive to the rear wheel.


    Attached Files:

  2. gone_fishin

    gone_fishin Guest

    i LOVE it!
  3. srdavo

    srdavo Active Member

    a great man once said......"can I ride it, when you're done?" ( was just me...:lol:)

    looks good!!

    RATRODER Guest

    ocscully,all belt drivetrain honda? off the shelf bolt on bolt on parts would be nice. keep us up to speed.louis
  5. azbill

    azbill Active Member

    very cool project :D
    I like it !!!
  6. iRide Customs

    iRide Customs Member

    Looks pretty sweet!
  7. forrest

    forrest Guest


    Wow! Looks great, Thats going to have a nice vintage look. Keep us posted.

  8. ocscully

    ocscully Member

    Possible New Suspension Fork?

    I Bought a very dirty Lightly used ProFlex 755 this past weekend for $20.00. Thinking about parting out the bike and using the Fork on this bike project.


    Attached Files:

  9. azbill

    azbill Active Member

    cool forks !!!
    should look/well on your project
  10. forrest

    forrest Guest

    Hello Ocscully

    Do you have any updates on your project? Would like to know more about it.


  11. ocscully

    ocscully Member

    Progress has been slow of late, but I did manage to get the Horizontal rear drop outs brazed into the frame today and have built some wooden models of the various toothed sprokets from Viza that I will be using to mock up the primary and secondary belt drive systems. I've also been working on modeling the engine/jackshaft mounting plate. I'm attempting to isolate the engine from the frame as well as make it possible to adjust the belt tension of both primary and secondary with out the use of seperate idler pulleys.
    If the weather cooperates I'll try and throw the mock up together tomorrow and shoot some new photos. If you have any specific questions let me know here or PM and I'll try my best to answer promptly.

  12. Bean Oil

    Bean Oil Guest

    Outstanding work so far!

    I like the concept of the driveline too. Excellent!

  13. ocscully

    ocscully Member

    Photo Update

    Had some time at lunch this afternoon to shoot some quick photos of my project. They don't show the mocked up drive train because there was a bit of a snaffu with the model of the final drive pulley and there may be a clearance problem. I'll have more time tomorrow to play with things and with luck will have photos of the drivetrain. The new fork is shown without the spring that provides the suspension and the Horizontal dropouts are shown without their tensioners.


    Attached Files:

  14. ocscully

    ocscully Member

    Project Resumes

    After sitting dormant for six weeks I'm back at work on the project in my slow and plodding way. The most recent addition is the base structure for the engine mount. It consists of a vertical web/gussett running between the seat tube and downtube along the top of the frame extension tub. This gussett is capped/T'd with a 3in wide plate running the full length of the gussett. The plate edges are rolled/bent 90 degrees to provide stiffness. The engine will be mounted to a seperate plate and then mounted to the base shown below with 15mm of vibration dampners sandwhiched in between.


    Attached Files:

  15. mickey

    mickey Guest

    That should be plenty strong.
  16. Looks like it may even clear the pedals,especially the engine's going up a bit.
    I can't wait to see this when it's done.
    So ya think it's gonna hold 5 gallons?
  17. ocscully

    ocscully Member

    Engine Mount & Drivetrain Mock-Up

    I've made some plywood models of the various parts I'm considering purchasing from Viza Scooters for the drivetrain of the bike and threw them on the frameset early this morning to see if there is any chance they are going to accomplish what I hope they will. The main pieces are the three toothed sprockets/pulleys for the belts and the jackshaft assembly. The parts as purchased from Viza are made to be used with 25mm wide HTD timing belts and come in three different sizes (20t, 70t, &102t) The drive- train shown uses two 20t and one each 70t & 102t. The Primary reduction shown is 20t-70t and the Secondary/Final is a 20t-102t. Total reduction for the drivetrain 17.5:1

    The side view of the engine mount is showing 1/4in. mounting plate sitting on top of 3/4in of vibration dampening mounts or pad.


    Attached Files:

  18. That is probably the coolest thing I have ever seen in my entire life. I love your project.
  19. Questions:

    1. This assembly completely bypasses any sort of gearbox. Can you still ride the bike like a regular bicycle or is it going to be entirely motor driven?

    2. Does this result in more clearance between the stays and the frame so you could fit a fatter tire in the back?

    3. How do you plan on attaching the wheel sleeve? To the spokes?

    I'm genuinely interested in this setup now. You are a visionary, sir.
  20. ocscully

    ocscully Member

    Although not shown/seen in the mock up, the engine will have a centrifical clutch on the output shaft. So yes you will be able to ride /pedal the bike.

    What you termed as the "wheel sleeve" (and I agree with you it does look like one in the photos) will actually be a pulley that will mount to an adaper plate that will bolt up to the rear hub. The wheels shown are just for the mock up. I'll be building a new set of wheels for the bike. The rear hub is going to be a Nashbar Single Speed Cassette Disc Brake Hub, so the rear pully will mount where the disc rotor would normally mount. For mock up purposes I cut the center out of the model to allow it to sit right on the spokes. There are clearance issues with this set up but but they are mainly with rear spacing and belt clearance were the belt passes the chain and seat stays. So there will be some modifications made to the various parts to make it all work out. The primary modification will be to respace the rear hub to 150mm. It comes from Nashbar spaced at 135mm. I'll be adding 5mm to the right side of the hub and an additional 10mm to the left side. As for tire clearance I think that a 2.2 would probably be the largest size tire the would fit this bike due to the dimensions of the Bridgestone rear triangle.

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  1. ocscully