my bike frame is to big for me.

Discussion in 'Motorized Bicycle General Discussion' started by mirage, Mar 24, 2011.

  1. mirage

    mirage Member

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    Hi. all. finally finnished my motorised bicycle, a mongoose 26in 21 speed montain bike, using a 49cc huashenge 4 stroke, it was the only frame i could find in the uk to get the engine in. Looks good. but unfortunately. my feet don,t touch the ground, and i can,t get of it without falling. I could just cock my leg over the saddle. but there is not often enough time for that, the tank is in the way, so can,t move down on to the cross bar., i could mount the tank behind the seat, spoil the look. or put a smaller rear wheel on. but that would create a lot of work, brakes would not line up . gearing ect. It was just rideable without the engine. and i could handle it, but with the engine and extra weight. it,s bloody dangerouse for me. tried different saddles, not much help. I need 4inch blocks on my shoes LOL. so looks like i may have to sell it and start again.

    ALso the engine came with a 48 tooth rear sprocket/ it does not look as this will climb any gradient at all. only tried it in the garden, and even a slight incline would not pull up it. i think it needs a 56tooth or even a 70 plus, as i live in a hilly town. blowbyu.com i saw his hill climbing test same engine, was impressive. or maybe a 9 tooth drive sprocket.

    However this is accademic till i can find a safe way to get off it. or get my feet on the ground. even my toes would help. otherwise i am likely to fall into the traffic.
     
    #1 mirage, Mar 24, 2011
    Last edited: Mar 24, 2011
  2. Nougat

    Nougat New Member

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    Take some pictures and let's see it, but I'm betting you could find or fabricate a lay-back seat post that would allow you to put the seat way down, and a little farther back, kind of in the nook between the front of the rear wheel and the seat tube.
     
  3. newbie tryin

    newbie tryin New Member

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    Hey there! i am sorry to hear about your difficulties, but I am sure we can sort it out, a lot of us here are a clever bunch.

    obvious question, but, Did you try lowering the seatpost?
    [​IMG]

    you might have to try a smaller set of wheels, and i am presuming you have a SI mount (v brake) setup?

    try (google) "long reach brakes", there are two brands i know of that can reach smaller tires.

    alternatively upgrade and get a disc brake "theraphy conversion kits"http://2btherapy.com/index.php/bikes/brake-therapy-conversion-kit
    but this might be very costly.
     
  4. professor

    professor New Member

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    A 21 inch mountain bike frame is really tall -much taller than a road bike, your only option is to cut and re-weld the frame (if you don't want to put 20 inch wheels-which would fix your gearing issue, by the way).
    Didn't you try to ride the bike before you motorized? I have a similar size frame and use 24 inch wheels and a low seat. I am 5'7 and this works for me.
     
  5. deacon

    deacon minor bike philosopher

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    I almost always have to put a small rear wheel at least on the bikes I build. I have balance issues and 26" bikes throw me when I try ot get on of off. Sometimes they even jump on me.
     
  6. mirage

    mirage Member

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    thanks guys. i have decided to put a tank under the cross bar, plenty of room, then i can move down onto the crossbar, i must have been doing this automatically when i tried the bike before putting in the engine, then when this option was no longer available, it was a whole new ball game. I am 5ft 7in my toes still only touch the ground when sitting on the cross bar. but it would be rideable. I don,t want to hack the frame about, spoil a nice bike, the gears are perfect. may install a jackshaft, now blowbyu.com have a kit for a 4 stroke huasheng. I bolted an extra pedal to the stadard bike pedal to give me clearance on the engine. i gave a lot of details to the proffessor. but my letter got deleted. the not signed in problem. i was, but it don,t seem to work most of the time. Now i want a fuel tank, any suggestions??
     
    #6 mirage, Mar 25, 2011
    Last edited: Mar 25, 2011
  7. mirage

    mirage Member

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    would be to far back then. i think a tank under the cross bar, or on the forward down tube would be ideal, but i would need a carb that sucks upwards, as i would lose the gravity feed.

    If it looks to good to be true, don,t tell anyone.
     
  8. retromike3

    retromike3 New Member

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    Don't use it

    First of all you have to be able to use the bike as if it did not have a motor. Back when I sold bikes I had people stand over the bike and if it was a road bike you should be able to pull up a good inch and a half. For a mountain bike it was a good three inches stand over hight. Before anything else that was the starting place. Today many bikes have a upwardly sloping top tube so you need more stand over room than you did ten years ago. I personally don't like this design because its not as efficient(to me it looks dorky too). The more upright your upper body is the more air resistance you create. Be that as it may, I highly recommend you get another frame, something that you feel comfortable riding without a motor before you power it.

    What I did was I went to the local used bike shop (city bikes) and picked up an old Giant mountain bike and converted it over to my needs. I shelled out about thirty-five dollars for it and its still working today.

    mike

    When my current motorbicycle engine blew up I se it up as a "get around" bike I installed a front derailleur and a small front chainring and road it till I got my new set up going.

    mike
     

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  9. mirage

    mirage Member

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    you are right up to a point. i did ride the bike first as i wanted to see how the gears compared to my old moutain bike, and found i could go up a brick wall in bottom gear, and the top was higher, i could just handle it frame wise. and it was the only frame i could find locally to get the engine in. What we want in the uk is manufacturers to build schwinn type frames, with disk brakes front and rear, then we have an easy starter. However this morning i realised on looking on youtube that there is a fuel tank that fits on top of the engine. i think they where made for mounting behind the seat.

    Well i have not been able to find a supplier, of this tank. i have seen them on a honda 50cc. but don,t know if they fit the huasheng also. I think i have enough room above the engine. will know more when i can get some measurments of this tank. It would solve all my main problems. The tear drop tank was to big and ugly anyway, who thought it was a good design to have a chimney stack as a fuel filler, it only needed to be a half inch off the top of the tank. would look much better. what we want is an under the cross bar tank made, as a choice for us. as i have all cables running along the top of the cross bar,

    and that gave me problems packing the tank up. so i did not crush them. I could put a tank on the rear parcel shelf as an option. but tank above the engine would look neater. thanks for your input. and the rest of you.
     
    #9 mirage, Mar 26, 2011
    Last edited: Mar 26, 2011

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