Years ago a road biker friend of mine at work told me about the Swift folder, and then Jeremy based one of his ebikes on one (suggested by JennyB), so I have been following this bike for a long time, and planning to make an ebike with one. A few years ago I bought one and started a BBS02 build with it, and then I bought another one for a test of the Luna Xiongda dual speed front hubmotor. The Blue Swift BBS02 project got sidetracked and the Silver Swift was set up first. Other things have interfered with my ebike journey, so things have moved slowly on all my ebike projects.
Here's Jeremy's thread:
https://endless-sphere.com/forums/viewt ... =3&t=42133
The goals for both of my Swift folding ebikes are pretty much the same. To have ebikes that are lightweight and easy to take places (in vehicles), that can handle steep gradients at least up to 15% (hopefully more), that are configurable for short or medium range, to take camping, etc. The two machines approach these goals from very different directions - a mid drive vs a geared front hubmotor.
A standard small geared hubmotor might have difficulty making a 15% grade, but the combination of the small 20" wheels and the retro-direct gearing in the dual speed hub give it the capacity to climb a steep hill. Other solutions to this such as large hubmotors or full size geared hubmotors could make the grade but at significant weight, and one of the goals is to keep this light. I also considered dual small geared hubmotors, and those would do the job, but at increased complexity, with dual controllers and motors and the wiring, etc that goes with that.
The BBS02 mid drive, with proper gearing will clearly climb the really steep stuff, at the cost of more chain maintenance. There is a downside to the BBS02 on the Swift, as the motor interferes with the folding at least a little. If the motor is positioned under the chainstays the interference (to folding) is reduced to a small and tolerable level, but then the torque reaction of the motor will tend to rotate it away from the chainstays and there is nothing to help stop it from moving. Solving this problem will be one of the pieces of this puzzle.
In the interest of full disclosure the dual speed hub in pre-built wheel kit was provided by Lunacycle for my testing, this included the usual controller, cabling and the display / throttle / etc. The rest, including batteries, bikes, etc. was purchased by me. The BBS02 kit was purchased from Empowered Cycles, and Matt attached it to the Swift frame.
The other pieces to this puzzle are the batteries. To keep the bikes light we want small batteries, and to meet different range requirements it is best if the batteries are reconfigurable. I selected 14S / 58V fully charged for compatibility with the Diamondback Overdrive that I have, and for the several batteries and chargers I already have on hand in that range. The small Luna 6AH pack fits in an underseat bag, but only having one of those I decided to try out the EGO Power+ tool battery as well. For longer range trips I have a 14S Shark pack that I bought a few years ago that might be possible to use, though it is getting big and heavy. These are all 18650 based packs. The Lipo bricks I have are 6S, so they are not ideal for a 14S system, though they can be pressed into service if needed.
The EGO batteries are 14S packs with built in BMS, the particular flavor I have is 2.5AH, so the plan there is to set things up such that I can run one or two in parallel. I have a separate thread on the EGOpowerPlus batteries and the 3D printed mounts I am working on for them.
EGO Battery Thread:
https://endless-sphere.com/forums/viewt ... 14&t=93563
I have done a few test rides with the Luna dual speed front hub. It climbs a 15% grade nearby, and on the level it seems to be quite efficient, not taking a lot of power. The setup needs more work on the wiring and organizing the components for staying conveniently out of the way when folding. it is not a speed daemon, I'll have to take some accurate measurements, but the most power I generally see is about 650 watts. The small wheel likely keeps the power down and limits the max speed, but it has lots of hill climbing torque.
There will be more later, and I will add photos, etc.
Yesterday (3/31/2018) I was looking at the Xootr site for some Swift information and I didn't see the pages that were there before, the Swift is mentioned only on the "discontinued" page. Very sad to see them go, if they are in fact discontinued. This thread is about my Swifts. For more historidcal and other info on the Swift folding bicycle see