70s schwinn speedster project.

cloakedvillain

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Edit: Got the jackshaft working but ultimately I've decided to run the china doll as a single speed. It ruined the look of the bike and the stock engine has more than enough power when used as a helper, my earliest posts say this and I stand by it. The only problem is that it is hard to manage the throttle and focus on everything else you manage when cycling.

Changed the title of the thread to be more accurate.

The bike is a schwinn speedster from the 70s, diamond frame, I am going to get drum brakes for front and rear. The plan is to use my 50cc and my SBP jackshaft kit to directly power the rear wheel, which is a 3 speed and have a freewheel adapter on the jackshaft with a crank arm on it to start the engine.

Right now I am waiting on the hubs and necessary accessories to come in, so I can have the shop build them up and then get the bike working by myself as a regular bicycle before I try to motorize it.

Supposedly through some fermi calculations the 3 speeds can handle 73 ft lbs of torque I don't believe it but the reduction would only be putting in 28.4 ft lbs at peak power, so we will see. (https://bicycles.stackexchange.com/...rque-on-sturmey-archer-internally-geared-hubs)

Some e-bike builders have run three speeds with bbshd motors which can put out 118.08 ft lbs of torque to varying success but the ones who had the least trouble had the torque curve up gently instead of peak torque instantly. Similar to how ICE have a torque curve unlike electric motors which have a very linear increase of power with the torque being constant.

Will update this thread as the build comes along. I may just put together a more traditional build if this doesn't pan out.
 
The bike is a schwinn speedster from the 70s, diamond frame, I am going to get drum brakes for front and rear. The plan is to use my 50cc and my SBP jackshaft kit to directly power the rear wheel, which is a 3 speed and have a freewheel adapter on the jackshaft with a crank arm on it to start the engine.

Right now I am waiting on the hubs and necessary accessories to come in, so I can have the shop build them up and then get the bike working by myself as a regular bicycle before I try to motorize it.

Supposedly through some fermi calculations the 3 speeds can handle 73 ft lbs of torque I don't believe it but the reduction would only be putting in 28.4 ft lbs at peak power, so we will see. (https://bicycles.stackexchange.com/...rque-on-sturmey-archer-internally-geared-hubs)

Some e-bike builders have run three speeds with bbshd motors which can put out 118.08 ft lbs of torque to varying success but the ones who had the least trouble had the torque curve up gently instead of peak torque instantly. Similar to how ICE have a torque curve unlike electric motors which have a very linear increase of power with the torque being constant.

Will update this thread as the build comes along. I may just put together a more traditional build if this doesn't pan out.
My method of shifting is to use a tachometer to shift by. That way I don't over load the drive train components at full throttle.

On my 4 stroke at full throttle I use a gear that keeps me between 6000-7000 rpm. Meaning if I drop below 6000 rpm I down shift. If I'm going above 7000 rpm I up shift.
 
My method of shifting is to use a tachometer to shift by. That way I don't over load the drive train components at full throttle.

On my 4 stroke at full throttle I use a gear that keeps me between 6000-7000 rpm. Meaning if I drop below 6000 rpm I down shift. If I'm going above 7000 rpm I up shift.
Sounds good, I plan on keeping the little engine around 4 to 5 k with an arbitrary 5.5k red line. I do have a tach and a bike computer waiting to go on the bars.
 
Dropped off the hubs at the shop today. Here's how the bars look.
 

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