Originally Posted by twowheeledfox
First off sorry for a new thread but the old one was cluttered and OT.
First a quick overview of my build- if you are not interested just skip to the questions (I do need help on these please).
First pic is of my build at the moment.
I used a standard, mid-size 26" rigid ATB frame, stripped of stickers etc. Rear wheel was trash and went to the scrap yard. Front wheel is a decent aluminum/ steel spoked assembly and will stay on the bike.
Brakes: V-brakes front. No rear brakes as of yet. PITA to adjust them but they are very powerful.
Wheels: front 26" aluminium, rear unknown as of yet
Seat: Vintage Viscount springer (makes it look like an old BMW R36 seat, look it up)
Bars: Chrome risers for a comfortable ride
Motor/acessories: 2-stroke 68.5cc slanthead kit, "silver" paint job that looks okay, using kit clutch and brake levers, grips, electronics, tank, etc. Has pullstarter.
Gear: Large rear reflector, hillbilly-made headlamp (turn signal case from an old motorcycle, sawed off the rear cap, inserted a cheap LED flashlight, clamped the light to the case and used some scrap aluminum to mount to the bars), Bell toolbag with full toolkit, rear rack with 2 gallon spare gas can, motorcycle mirror off a Honda CB350, walmart digital speedo, standard tires and tubes.
Question: Would an external gearbox, Non-jackshafted, work on of these china motors? Here's my idea (See 2nd and 3rd photos for my dummy setup): Using a flipped front derailer from a bicycle, right under the motor's lower chain output. Put a lower sprocket such as a 44 or 48 in the derailer's lower gear position, and a higher sprocket like a 36, 38 or 40 in the derailer's higher position. I already thought about chain alignment but a properly spaced 2-speed shouldn't do too bad (let me know if otherwise of course). See pictures for true detail.
The goal of this whole thing is to put together a 2-speed gearbox for the stock China kit that is cheap and can be made using regular bicycle and hardware parts. 2-speeds is just right for these motors, one to start off in/hillclimb and one for cruising. That way 30mph is doable calmly and the clutch won't fry every time you take off from a stop. It would also work for stock HTs, make things a bit more universal and make the list you tell a new MBer to get easier, ie motor kit, lights, trans.
Would really like some input on this, again see 2nd and third pics for the dummy setup.