Flevo Bike has rather unique python-style (Moving Bottom Bracket) front wheel drive recumbent frame design. Steering is implemented by bending the frame in the middle under the seat. This way steering is controlled by driver legs rather than handlebars. Initially I bought the frame, seat with custom Ventisit cushion and rear rack. All other components were off-the-shelf and standard. This bike needed some time to get used to it, but very comfortable afterwards, especially on the long rides.

After the first season of riding, some drawbacks became obvious. It was rather tricky to start moving due to pedal steering, especially on incline. This made using bike in city environment quite hard. Also majority of the weight is concentrated on the back wheel, so front wheel lacked traction on inclines or slippery terrain. And, of course, it is a recumbent, so climbing big hills was rather challenging. Last problem could be fixed with more training, but the other ones needed an engineering solution.

Before the second season, I’ve bought a electric conversion kit, with 1kw motor, some basic controller and 48v 20Ah battery. Due to motor width, I had to ditch disk brakes on the rear wheel and replace it with V-brakes - It will become important a little bit later. Also I’ve replaced a rear silent block suspension with proper spring.

Electric drive made miracles for that bike. Now it became All-Wheel-Hybrid-Drive Recumbent. Maneuverability increased dramatically, starting wasn’t a problem anymore, even on steep inclines. I’ve modeled the frame in Fusion and 3D printed some cases for electronics and wires, drilled some holes for internally routed wires, modeled holder for phone and display. I’ve made 100+ km a day trips on this configuration and this was just great.

However that was not ideal) Controller lacked regen capabilities - braking on long hills was a problem, as with recumbent aerodynamics, bike easily reached 60km/h on downhill, without pedaling. There was no assist mode and controlling power with throttle on rather powerful motor was tricky. And last but not least, motor was quite heavy - over 8kg. The last straw was drawn when during a long several km steep downhill ride rear tube exploded due to overheating from the v-brakes. I definitely needed regen.

So I’ve ordered Grin All-axle kit with Cycle Analyst, Baserunner and torque-sensing bottom bracket (Or should I say front bracket in case of recumbent). Some component location changes were necessary to fit Grin kit. Even more 3d printed parts needed. All the extra features made this bike even closer to perfection. With regen and proportional assist hills aren’t a problem anymore in both directions. Especially with constant regen on downhill. I could even pedal rather hard on downhill to increase battery charge even more.

To monitor the performance of the electric drive, and generally for statistics and the ability to share tracks, I added a Raspberry Pi Zero with custom software. The microcomputer is connected to the serial port of the Cycle Analyst as well as to a GPS sensor and power sensors. I had to add a step-down DC-DC converter for 24V, which further steps down to 5V for the electronics. Having 24V allows charging any Type-C electronics from the bike using car chargers. Very compact modules for car sockets allow for up to 120W of charging power.

By the end of the season, I was able to produce a new, extended rear fork. The new fork allowed me to install a rear fender and eliminate splashes on the back of the bike. There are significantly more options for adjusting the height and choosing different shock absorbers, making the ride a bit smoother overall, and the shock absorber no longer hits the wheel in extreme positions. The fork was initially designed with a center kickstand in mind, but the kickstand itself still needs to be designed and manufactured.