What's a Good Bike Should I Use for a Jackshaft/Shifting Kit

Discussion in 'General Questions' started by BigSam, Oct 11, 2014.

  1. BigSam

    BigSam New Member

    Right now I have a 49cc bike on my 29er mongoose and its just no fast enough. I still want to use a 49cc engine but i want to keep up with traffic and want to get going around 40mph. money is tight too. Any Ideas

  2. troyg

    troyg Member

    You need a motorcycle or scooter.MAB's aren't meant for that type of speed, at least not in public.If you do those type of speeds one of these are sure to happen:
    You'll get very hurt
    You'll die
    You'll get your bike confiscated, and get some hefty fines
    You'll ruin it for every other MAB rider in a 500 mile radius.
    Fabian and Timbone like this.
  3. butre

    butre Well-Known Member

    you won't keep up with traffic using a 49cc no matter how much money you dump into it.
  4. Fabian

    Fabian Well-Known Member

    You are crazy if wishing to do 40mph on a motorised bicycle.
    A sensible speed is 25mph.
  5. Fabian

    Fabian Well-Known Member

  6. Timbone

    Timbone Active Member

    I am very pleased with my MAB but, I share your feeling that "it isn't fast enough"! I can tell you with all seriousness that I can go much faster with a group of strong bicycle racers on my pedal bike.

    Low grade bicycles are not designed to go 40 mph. High mileage at 25-29 mph puts a serious strain on the rear wheel. I'd put a smaller sprocket on the rear but the stress on the rear wheel would be too much, I fear.

    As a very experienced bicycle racer, I've seen high speed wobble take riders out at high (40+mph) speed - and this is on high $$$ bikes that are designed to go fast! Get a cheapo bicycle up to 40mph and anything bad can happen!

    I'd love to go 40 mph on my motorbike but that's asking too much. Keep in mind what these are: highly efficient, short range vehicles, with a very limited speed.

    Good luck to you.

    Lloyde likes this.
  7. butre

    butre Well-Known Member

    I've hit 60 downhill and didn't experience any speed wobbles. true wheels, slow steering, and a stiff frame helps. race frames often sacrifice rigidity for weight and have fast twitchy steering.

    the major problem with hitting high speeds on a well sorted motorized bike is in it's braking capabilities. even top of the line disc brakes are often inadequate at those speeds.
  8. Timbone

    Timbone Active Member

    I've done several high speed descents on bicycles in the 50's, approaching 60mph, and I have never had any high speed wobble. But I will never forget seeing a guy descend next to me at about 45mph succumb to a high speed wobble and jump right into a stone wall on the roadside. That make of bicycle was a very high $$$ Litespeed. He was hurt but, thankfully, not killed.

    A motorized Huffy going 40 mph? Now that is scary!

  9. pbeggs

    pbeggs Member

    40,.. ok to get there safely would be expensive (lots of stuff to upgrade)
    should not be attempted without a high quality frame , serious brakes (large diameter disks,.. rim brakes will not do) heavy duty wheels (something designed for a tandem bike) suspension,.. full lights (front and rear),.. safety equipment (real helmet),.. then 49cc would be somewhat lacking for the task,. it would probably be cheaper to buy a used scooter that has all this stuff and would be legal,.. i have done all these upgrades,.. and i have geared my mb to top out at about 30,... but i rarely go that fast 25 is a good cruising speed anything faster is the domain of a different vehicle
  10. Fabian

    Fabian Well-Known Member

    :iagree: especially if the bike is fitted with rim brakes.