Has anyone thought about building a hybrid bicycle with an electric CVT? (Basically, it would work like a scaled down version of the CVT in the Prius, with the pedals instead of the engine.) One motor is directly coupled to a wheel, and the other motor has the shaft coupled to the rear wheel, the casing to the pedals, and slip rings used for the electrical connections. Two bidirectional DC/DC converters connect the motors to the batteries, with a microcontroller managing power flow.
To ensure it rides like a normal bicycle, the "gear shifting knob" will control the proportion of pedal speed to wheel speed. In other words, the microcontroller will measure the wheel speed and calculate a pedal speed based on the "gear ratio" selected by the knob.
* If the pedals are rotating faster than that, one DC/DC converter will pull power from the split motor to load down the pedals to slow them down to that speed while the other DC/DC converter will supply power to the wheel motor to (by default) net zero battery current.
* If the pedals are slower than the calculated speed, the motors will be inactive and the bike will "glide".
* If the pedals are going backwards, the bike will regen at a rate proportional to the speed of the pedals going backwards. (In other words, pedal backwards to regen!)
* Optionally, if the pedals are moving while the brake is engaged, use that to recharge the batteries.
To make use of electric boost, a twist handle will be used to control battery power used for boost just like a regular electric bike. (Optionally, the handle can twist backwards to engage regen, as an alternative to pedaling backwards. It can also allow for regen while pedaling forwards.)
The display panel will be based on a small video LCD, so the display layout and data will be defined by software. (A cheaper alternative can be a plain text LCD, although small video LCDs are cheap nowadays, often cheaper than some text LCDs! However, text LCDs are orders of magnitude easier to interface than video LCDs.) It can be programmed to look like a panel of meters (either digital or "analog"), a pictorial diagram, a combination, or whatever else you like! What I think would be interesting would be an animated diagram with icons of the wheel, batteries, and pedals arranged in a triangle. Arrows of varying sizes would show the flow of power when in operation (pedaling, boost, regen, and pedal recharge). For additional information, a few meter displays would be used. The diagram can also include the motors to be more accurate, but that would probably clutter it up too much.
The microcontroller would have to be advanced to accommodate the sophisticated system, so it would likely be something like the Parallax Propeller as it would be well suited for the many threads needed.
I don't think I'll actually build such a bike as bikes are of very limited use in my current neighborhood, but I will be happy to help with the development if someone else wants to build one.
Check
hybrid bicycle with electric CVT? - CleanMPG Forums for an existing discussion about it.