The Royal has a massive amount of space in the frame for your extra components, in this case, a motor, batteries and a jack-shaft. But being a stretch-cruiser, the bottom-bracket is well forward. I toyed with the idea of relocating it, but ultimately decided I didn't need to. The design I came up with would use the space fully without projecting out sideways as much as Juicer 1 did. Also, like the subsequent Juicers, the BB spindle, motor-output shaft, jack-shaft, and rear axles would all be on the same line. This prevents chain-line interference and is visually pleasing.
Okay, that's not a crazy amount of welding on the frame and I didn't have to section it anywhere. The jack-shaft mount on the seat-post tube is rigid, but even so, the position of the shaft's axle will be adjustable allowing the possibility of chain tensioning or a choice of different transmissions.
Oh yeah, check out my new center-stand. It's an elegant Swiss design. It's not the cheapest, but has great clearance and folds up on one side. I will go over the budgeted weight rating, but Archimedes tells me that if I cut the legs down a few inches I'm back in black.
After dropping in the components, the alignment looks good. Once again I am using a Currie type motor rated at 1000w. This time my jack-shaft is a Shimano automatic 2-speed Sram hub with an 18T sprocket welded on. My hope is that this will help me accelerate faster on the flats and climb my neighborhood's hills at slow speed.
The plan is to to use all the mounting holes on the motor, but so far, two are in the wind. In this photo I am bending a floating bracket to bridge the rear-facing hole and the jack-shaft axle (Bite marks? Yeah, I got 'em). The stability of this bracket will not depend on friction alone. The jack-shaft axle has flat sides which this slides on to. Also, I welded a strip to the back of this piece that keys into the rigid slot on the right jack-shaft mount. These features will resist any tortional force from the motor.