Building a mono-shock frame to mount any size tire or engine.

Discussion in 'Motorized Bicycle Welding, Fabrication and Paintin' started by miked826, Jul 23, 2013.

  1. Dan

    Dan Staff
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  2. miked826

    miked826 New Member

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    DB, I just ordered the carbon steel tubes for my frame about an hour ago. Cost me $125 after tax and shipping from Nova Cycle Supply. The front half of the bike frame will be a larger version of the Felt Slater/MP frame with the exact same tube angles but with a longer seat tube by about 3 inches. It will be able to swallow a Honda GC160 with room to spare, using a normal 4 stroke motor mount. That is the motor this frame is gonna be built around.

    When I get the tubes, then I gotta notch those things. I guess it's time for me to put up or shut up, aye? LOL
     
  3. miked826

    miked826 New Member

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    I will be using the same 52 tooth chainring as shown in this pic. Except my custom frame, using that same engine mount will hold a Honda GC160 with 2 or 3 inches clearance above the GC160 to easily service the spark plug or adjust the valves without having to remove the engine. That's my plan, now I just gotta make measure twice and cut once...... the first time around. LOL

    [​IMG]
     
  4. Dogtown Burner

    Dogtown Burner New Member

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    sounds *****in' Mike. I can't wait to see it. and the top tube! whew, thats an undertaking, and my kinda build! I love the tank bikes. I'm building a gx200 Electra for october race. (not a frame-tank, i'll be using a wolf creative customs tank). It's definitely a nice sized can of worms. hahahha.
     
  5. miked826

    miked826 New Member

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    I got the largest top tube that Nova sells, 42mm. I would have got a 42mm down tube as well but that engine mount is made for a 38mm down tube, so thats what I got.

    I originally planned on a frame built around the GX200 but changed my mind after I went over it's length and width measurements over and over again in my head. I want to keep the same tube angles and tube lines as the Felt Slater/MP, only a taller version of it. So I scaled my engine plans back down to the GC160. I bought no seat or chainstays as I have no plan on having any of those. I'm still h3ll bent on the swing arm with 3.5" Shinko SR244 tires.....front and rear. I'm not concerned about pedaling..... as you can see, but it will have them. LOL

    [​IMG]
     
    #25 miked826, Aug 22, 2013
    Last edited: Aug 22, 2013
  6. Dogtown Burner

    Dogtown Burner New Member

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    are you going to build the suspension, or do the rusty-norm thing?
     
  7. miked826

    miked826 New Member

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    Not if I can help it, no. I wouldn't be building the frame either but my HS49 and bicycle tires just do not do it for me. It's just not enough (for me) riding on the roads and hills in LA, so I have no other choice but to build a frame that can easily fit monster size moped tires and a GC160.

    I'm gonna see what swing arms I can find on ebay from a small to medium size dirt bikes. There's tons of them on ebay. Whatever I finally choose, it wont look out of place or something out of a Mad Max movie that I just threw together. The swing arm will look like it belongs with the front half of the frame and it will be easy to acquire bunches of them. I'm not gonna use anything that's not easily available online in abundance and cost effective.
     
    #27 miked826, Aug 22, 2013
    Last edited: Aug 22, 2013
  8. miked826

    miked826 New Member

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    The swing arm has to match the Shinko in both depth and width. I'm not gonna use a swing arm that's too wide or too long for that Shinko 3.5" x 19" tire. I'm just not sure what size dirt bike that translates to just yet.

    I'm guessing it to be around a 125cc dirt bike....... roughly guessing. LOL
     
  9. culvercityclassic

    culvercityclassic Well-Known Member

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    Miked I see you ordered tubing for bicycle frames when it looks like you are going to build a bike that should be built out of motorcycle tubing. The GC160 is not a light motor, has some good torque and you plan on having a swing arm on the bike, thats going to require a structure built to withstand alot.

    I noticed on your bike that your seat has no springs, have you ever tried a spring type seat on that bike? Just wanted to see if it road any better with one.
     
  10. miked826

    miked826 New Member

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    Youre right, it should be built of motorcycle tubing but what is the cost differential? How much more is it? My Felt is packing some 80 extra pounds with the electric stuff and it's still in 1 piece. LOL

    It came with springs but I never installed them. My spine is fine going springless. I don't mind that. It's hitting any rut or hole in the road at high speed that causes my back end of my bike to act like it just ran over a land mine. I do not have enough tire on the road to dissipate that kind of shock.
     
  11. miked826

    miked826 New Member

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    A Harley hard-tail can get by with with no rear suspension cause it has so much rear tire rubber on the road to absorb almost anything it runs over. Skinny bike tires have no such luxury, transmitting the shock throughout the whole rear of the bike, which does not impart stability at high speeds. I can offset it somewhat by standing up on the pedals but I don't what to have to rely on that all the time. Especially when riding in the pitch dark of night.
     
  12. culvercityclassic

    culvercityclassic Well-Known Member

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    I say a custom frame to accept your tire choice and a seat with a good mono shock built in would work fine.

    I am not sure how much tubing you purchased but for what you paid I could get you 20 ft of 3/4in, 20 ft of 1in and 20 ft of 1 1/2in, thats enough to build three frames. All this round tubing in .090.

    Plus that .090 is easy to weld vs that bicycle tubing...
     
  13. miked826

    miked826 New Member

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    LOL Holy Shiznit. I only bought enough to build ONE triangle part of the frame, the front half of the frame.... made of the thickest walled carbon steel they have. Live and learn I guess. I thought for sure it would be much more costly if it was motorcycle tubing.
     
  14. young grease monkey

    young grease monkey New Member

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    you cant weld chromoly with mig anyway, but you might end up with a ridiculously heavy frame using carbon steel. how thick of tubing did you buy? this is very interesting, not something i would try myself though. i would buy a motorcycle at this point, for what you want out of a motorized bicycle, but its a great challenge, plus how many people can say they really made their bike from the ground up with raw materials? thats awesome.

    i started with a frame and am fabricating everything i possibly can cuz im cheap and got more time than money sometimes haha. just a stick welder, grinder and drill press plus common tools get er' done. i hate to pay for something i can make
     
  15. miked826

    miked826 New Member

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    Not concerned with weight at this point. Just ease of welding. My Felt MP bike weighs upwards of 120 lbs and I weigh almost 200. My Felt MP is also carbon steel and is now approaching 4000 miles on it riding on the most grueling 3rd World roads in this country and shows little signs of wear, other than some paint scratches. LOL
     
  16. miked826

    miked826 New Member

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    DB, I saw VMB's swing arm bike. I only have one question. I have never seen a chain tensioner on any dirt bike swing arm ever in my entire life and yet the chain always stays on, on all dirt bikes just fine. Why is this so?

    If you draw a straight line from the clutch sprocket to the rear axle then the pivot point of the swing arm has to be mounted on that imaginary line, to the frame........ and then no chain tensioner is ever needed. If the pivot point is not mounted on that imaginary line then a tensioner would be absolutely needed.

    Fascinating. LOL

    [​IMG]
     
    #36 miked826, Aug 23, 2013
    Last edited: Aug 23, 2013
  17. miked826

    miked826 New Member

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    VMB's swing arm is not drawing an imaginary straight line between the clutch sprocket and the rear axle and it has to have a tensioner to compensate, because of that.
     
  18. Dogtown Burner

    Dogtown Burner New Member

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    And Yet...lol
     
  19. miked826

    miked826 New Member

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    Look how the swing arm draws a straight line right through the engine sprocket and the rear axle. It's universal, regardless of the dirt bike made, for a reason. Cause chain tensioners suck and they're gaudy looking! LOL
     
  20. buba

    buba Member

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    go to it mike

    tanks are happening -- maybe a bunch to show at willow in a few weeks??!!

    along with 72 chevy pu 3/4ton with hydraulic lift tail gate
    if it proves reliable (picking it up tomorrow after 3 hours at dmv today
    some paint tomorrow or Monday and then the tanks and frames for willow

    maybe some space for you if you want to go

    best buba
     

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