My experiments with the Crystalyte 405 motor on my recumbent have been interesting, but have convinced me that an "automatic" system would be a lot simpler to ride. I've been giving this some thought and have come up with the following simple scheme.
Right under the front edge of the seat there is an idler wheel that supports the top of the chain. If I were to add another, spring loaded, idler wheel above and in front of this, then increasing pedal effort would tend to move this idler upwards. It would be a simple matter to turn this small movement into a signal that could be processed to drive the controller throttle input.
The signal would need to be modified by a pedal speed signal, to prevent the controller giving power when the bike is stationary but with pressure on the pedals (which is common on a 'bent, due to the way you have to start off from a standstill, with the brakes on).
My thoughts are to measure chain speed at the idler, together with chain deflection (pedal torque) and combine these signals into a control voltage for the controller. This would be very easy to do using a small microcontroller, which would also allow the selection of varying levels of "gain" in the system, so effectively controlling the assistance level per unit pedal torque.
Overall, the system should be fairly straightforward to build and may well work on a conventional bike as well. The fact that there doesn't seem to be an add-on like this on the market makes me wonder if I'm on the right track with this. Any comments or observations would be welcomed.
Jeremy
Right under the front edge of the seat there is an idler wheel that supports the top of the chain. If I were to add another, spring loaded, idler wheel above and in front of this, then increasing pedal effort would tend to move this idler upwards. It would be a simple matter to turn this small movement into a signal that could be processed to drive the controller throttle input.
The signal would need to be modified by a pedal speed signal, to prevent the controller giving power when the bike is stationary but with pressure on the pedals (which is common on a 'bent, due to the way you have to start off from a standstill, with the brakes on).
My thoughts are to measure chain speed at the idler, together with chain deflection (pedal torque) and combine these signals into a control voltage for the controller. This would be very easy to do using a small microcontroller, which would also allow the selection of varying levels of "gain" in the system, so effectively controlling the assistance level per unit pedal torque.
Overall, the system should be fairly straightforward to build and may well work on a conventional bike as well. The fact that there doesn't seem to be an add-on like this on the market makes me wonder if I'm on the right track with this. Any comments or observations would be welcomed.
Jeremy