How much space

Discussion in 'Motorized Trikes' started by chainmaker, Jan 31, 2010.

  1. chainmaker

    chainmaker Member

    I am building a tadpole based on Atomic Zombies warrior plans, and I am going to put a HT66 cc motor on it I will have begun building the frame before I get the motor. I will be mounting it on a "tail"(an extension of the frame) behind the seat. My seat back will be at 45 degrees, the question I have is I need a rough idea of how long of a "tail" to plan for between the seatback and rear tire for the motor and a jackshaft. What are the dimensions of the motor with exaust, and carb. I ordered the motormount from Manic Mechanic today and I am going to mount the flat bottom part to the "tail" I am using 1.5 x1.5 square tube so I think this will work out nice. I saw somplace a outline of a HT motor with a measurment across it, You were supposed to re-size it and print it out so that the written measurment was the actual measurment to see if would fit your application, does anyone know where I can find this again??Sorry about the longwindedness ...but this is driving me crazy. I am just looking for a ballpark number.
    Thanks for the Help
    Chainmaker
     

  2. SimpleSimon

    SimpleSimon Active Member

    Allow 11 inches vertical clearance above the mounting plate for your engine is a good rule of thumb. Since your seat back will be slanted at 45 degrees, the back edge of the seat needs to be at least 11 inches forward of the front engine mount - a 45 degree angle means that for each vertical inch the horizontal displacement is also one inch. I'd go forward a full foot, as your exhaust manifold comes forward off the cylinder.

    Remember, the wheelbase length affects the Ackerman angle needed for steering stability - basically, the longer the wheelbase becomes while staying fixed in width, the lower the Ackerman angle needs to be. Easiest way to deal with that is to draw a T to scale that matches your wheelbase length and width, then measure the angle of a line between the base of the upright (your main frame line) and the crossbar of the T at the tip (the crossbar represents the wheelbase width. Ordinary graph paper is great for this.

    edit: I just looked at the Warrior on AZ's site. I assume it is your intention to insert room for the engine behind the seat, and at the level of the seat bottom? If so, I'd lengthen the main boom at seat bottom heighth by 24 inchers, and then put in the angled riser to the rear dropout mount points, with a brace arcing above the engine space. The brace would be a good place to mount your fuel tank and your ignition module, perhaps a tool cache.

    Given the Warriors design, that lengthening WILL affect handling significantly.
     
    Last edited: Jan 31, 2010
  3. srdavo

    srdavo Active Member

    Ballpark.....

    Hi,
    looks like 13 inches will give you plenty of room... that includes clearance for the stock exhaust pipe.

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  4. srdavo

    srdavo Active Member

    I built my Tad seat at 45 degrees & for me, it was NOT comfortable. I changed it to a more upright angle. Not sure of the degrees.

    002.JPG

    Looks like I left plenty of room behind the seat, eh? hahaha
     
  5. chainmaker

    chainmaker Member

    When You say "Given the Warriors design, that lengthening WILL affect handling significantly" are you just reffering to the ackerman steering ? This is correctable using the graph paper method you described correct? If you dont mind let me ask you about the other mods I am planning, I would appreciate any feedback, this is My first build so I kind of jumped in and I am finding issues that I didnt think about
    1. I plan on widening the rear forks to fit a 27 x 10 x 15 racing slick
    2. adding angled supports from the 90 degree bend in the forks to frame right at base of seat
    3. The proposed horizontal boom extension to the rear of the seat would also go 6 inches in front of the seat tube to accomodate a bigger seat (for me and my little girl)
    4. Switching tubing size from 16 ga to 14 ga 1.5 x 1.5
    5. 20 in x 44 mm front bicycle rims with Pirelli 16 inch moped tires
    6. Reducing the angle of the seat tube ( your seat looks more comfortable) which I will gain more space behind, and not have to lengthen boom as much
    Besides Me being crazy, do You see any other problems brewing
     
    Last edited: Jan 31, 2010
  6. srdavo

    srdavo Active Member

    is this a car tire?
     
  7. chainmaker

    chainmaker Member

    Yeah... I spoked a 15x 10.5 wheel shell and found a hoosier drag slick to fit.
     
  8. srdavo

    srdavo Active Member

    Xtreme!!!!

    WoW!!

    Steering, at this point, doesn't seem all that important. (to me...... SimpleSimon will be able to help you with this) My questions involve whether the HT engine will make it roll & if it does.... how the heck are you going to stop it? That tire is a lot of mass....both to move & stop.

    I'm NOT knocking your plans, by any means. Heck, I like it!!
    I saw this beauty a few years back......
    http://www.motoredbikes.com/attachment.php?attachmentid=2301&d=1192302211
    http://www.motoredbikes.com/attachment.php?attachmentid=2302&d=1192302237
     
  9. chainmaker

    chainmaker Member

    Well I ordered a couple of 20mm hubs for the front wheels that have disc mounts, and I also posted a question about rear discs and was advised against it. Speed isnt a huge deal right now, just a comfortable cruise is fine.. I am planning on a Pirate Cycle motor one of their performance ones when they come out this spring. You can check out what I have started ,not much right now (too cold outside) at my build website www.badbrainschoppers.com
    Thanks
    Chainmaker
     
    Last edited: Jan 31, 2010
  10. srdavo

    srdavo Active Member

    Cool.... I really want to see this come together!!
     
  11. chainmaker

    chainmaker Member

    I have been planning it in slightly different forms since November, Ive been getting the parts all winter little bit at a time, still have a bit to go waiting on rims, and hubs to come in the mail. I have 10 days off the end of march I plan on getting at least a rolling chassis done then (its My first build), some prep stuff done before then. I dont have a garage(winter) and I work 6 days so I dont get much free time. So I am trying to work out as many bugs as I can before then.
    I will post any updates on the progress in this thread.
    Cheers
    Chainmaker
     
  12. srdavo

    srdavo Active Member

    I'm a big atomic zombie fan. Lots of talent on that site.

    Have you seen http://www.fleettrikes.com/ ??

    Look at the Tips/Tools/Help section----- on kingpins. great info.
     
  13. SimpleSimon

    SimpleSimon Active Member

    Chainmaker, what I meant in my earlier comment regarding your proposed changes affecting the handling is 3 basic issues -1) insuring that the front steering geometry is correct for Ackerman angle is imperative, and getting zero point suspension lean on each kingpin. 2) Lengthening the wheelbase will impact your turning radius drastically, and wider front rims/tires will as well, as you have to consider the arc the front wheels will swing through in turns - typically the wider the tire for a given wheelbase width, the less the allowable angle of turn (you definitely do NOT want a spinning tire rubbing against the outsides of your thighs), and 3) the seating height on the Warrior looks to be 6 inches or less - high centering the main frame gets more likely as it gets longer for a given height above the pavement.

    Along with those concerns, the longer the moment arm of the main frame tube, the greater the likelihood of rear wheel scrub when cornering, as well as torsional deflection of the dropout subframe. Going to bigger/heavier tubing is a good idea with your proposed changes. With the tadpole type recumbents, a CoG that is well forward (but behind the front steering axle plane) is important, because under braking forces the bike will want to nosedive - it is quite possible to lift the rear wheel off the ground. With the lengthened frame and the very large/heavy rear wheel, the CoG will shift backward. Which means that it may well be advisable to go with a disc brake on the rear of your design, but make sure that your force balance is at least 60/40 front/rear brakes - the front bakes must be primary and they MUST be balanced.

    I like what you are proposing to do, but please do think through each changes impact on the bikes useability carefully. Think about your chain runs, and what lengthening them and/or changing frame member angles will do to them. In addition, with that big a tire, how are you going to affect power transfer? Are you going to bring the two power systems (pedal and engine) together at a mid-drive unit before final transfer to the rear wheel?

    Most useful to me in design questions is a good 3D model - I use Google SketchUp a LOT - and then I try to put myself in the seat, mentally. I spend a good bit of time working out what forces will be experienced, in what directions, in use. Better to work out as many bugs as possible before investing effort in fabrication than in changing things afterward.
     
  14. chainmaker

    chainmaker Member

    I appreciate all the advice, I have all the parts for a mid-drive; jackshaft and an assortment of sprockets,freewheels,and adapters. I will be using a dual disc brake lever for the front brakes, I thought about the turning radius and I was thinking about lengthening the wheel arms in the front a couple inches each side.Chain managment and such, these are the things I go through mentally inch by inch every day on my 1.5 hour commute to work. I also try to put myself mentally in the seat and picture the layout. On which side of the wheel would you suggest a rear disc I will have pedal drive on right and motor on left, when I first thought about the need for a rear disc I pondered the thought of putting the gear cluster on the jackshaft and just a sprocket on the axel, and disc on the left side


    Chainmaker
     
  15. chainmaker

    chainmaker Member

    This is what I had in mind for a rear fork mod. Obviously its a chopper but I think it will work perfectly for the rear end. The bottom frame tube going right to the bottom back of the seat, and the top tube going to the top of the seat

    Cheers
    Chainmaker
     

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  16. Alaskavan

    Alaskavan Guest

    I found that stretching my tadpole stabilized the steering quite a bit. I also added handlebar extensions to the vertical steering grips to give a horizontal grip. I think I gain a bit of control by steering more with my wrists, instead of with the whole arm.
    While your racing slick will look cool, I would advise that you also build a more moderate rear wheel so you can mount the slick when you want to look - slick -. And you can mount a lighter wheel/tire when you want to ride.
     
  17. chainmaker

    chainmaker Member

    Good Idea....... maybe I will lace a 8 inch for when I want to be a little conservative. No,.... but I do plan on having a back up tire in case the fuzz give me grief about the slick, they make a street legal slick with just enough groove to be legal its got like 5 lines around it. I just have to wait for the guy to burn up a couple runs with it. I will though think about maybe a 4 inch and even that will look a little funny in a fork thats 13 inches wide.
    Cheers
    Chainmaker
     
  18. SimpleSimon

    SimpleSimon Active Member

    As far as final drive options go, I'd favor bringing the power and pedal drive trains together at the mid-drive, then doing a single final chain loop to the right side sprocket. That leaves the left side free for your disc brake rotor, and also puts the power through the gearing system - with that massive a rear wheel it might be very useful to have the option of shifting up/down for starts from a full stop and getting to cruising speed.

    Alaskavan's idea regarding interchangeable rear wheels is a good one, and if you were to do some modification of the frame, you could readily build a pair of rear drop out subframes that were interchangeable as well. Of course, your chain lines then have to move as well.

    I admit, the "street slick" rear tire sounds cool, but I'd hate to have to pedal that thing if the engine dies.
     
  19. chainmaker

    chainmaker Member

    I am actually planning a second bike for more practical riding this one is mainly a fun bike. Would I be able to shift gears under motorpower with a standard de-railer if the gear cluster was on the jackshaft?, for some reason I thought it would take somthing more heavy duty.
     
  20. SimpleSimon

    SimpleSimon Active Member

    Honestly, a two hundred pound man standing on the pedals and pulling on the steering of an upright bike can exert far greater torque on the chain and gear cluster than a small engine is ever going to put on it. For that matter, the pedal position of most full recumbents lends itself to exerting some fairly impressive pressures on the crank/chain/dérailleur system.

    That part of the idea really isn't a major concern, as long as chain tensions are set correctly and your chain lines are straight.
     
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