TimL said:
5: In the photo, you will notice a velomobile shell - we rotomould "Rotovelo" here - i'll be replacing my one with a new one soon and be getting electric assist - anyone want to suggest a hub motor system? Don't need high power due to the aero as you can easily get yourself into trouble... Probably 500w is plenty, but i still want strong regen.
Regarding the hub motor system, what are your goals? Are you looking for something that is direct drive or something geared with a clutch? How important is weight for your application? How important is efficiency for your application? What about cost? Do you need something that could go to a higher wattage value in the future?
A good all-around choice, if not a bit on the expensive side, would be a MAC geared hub motor, with the appropriate winding selected for your target cruising speed, voltage and drive wheel size. At 500W, the clutch would likely last the life of the velo(The composite clutch can get about 5,000-10,000 miles when run at 1500W peak so long as the phase current is kept in check and the current is throttled back if the motor gets too hot), and it can be mechanically decoupled from the pedal drivetrain to eliminate cogging losses so that the bike remains easy to pedal if the battery runs dead. You'll need a controller that allows the applied voltage to be varied so that you don't overheat the motor going up steep hills at low speeds. I'd recommend a FOC type such as the Phaserunner.
The Rotovelo has a CdA of 0.15 m^2, which is far better than any upright diamondframe bike, but not all that good as far as commercially available velomobiles go(It's about 1.5x the CdA of a WAW or Quest, 2.5x that of a DF XL, 5x that of a Milan SL). 500W should be good for 35 mph or so on flat ground with no wind, which given that there is no suspension, such a speed is only practical to maintain on smooth roads. The lack of suspension could really get you in trouble here if you decide to use a higher-powered motor. 1,500W would probably get it to 60 mph. If the Rotovelo had a suspension, it would probably safely be capable of maintaining car-like speeds when enough power is available to do so, and be a lot more comfortable to ride. The Rotovelo is a durable design, otherwise, whereas its competitors are comparatively fragile. The Rotovelo could also benefit by having attachable pieces made to seal up the chainline to keep dust, water, and debris away from the chain, lowering the maintenance requirements for the drivetrain and improving chain/idler/cassette/crankset/derailleur lifespan, and if sealing the rear up where the rear derailleur and cassette and rear wheel is exposed, it would likely reduce drag at least slightly.
Overall, I think the Rotovelo is a promising design, but a few modifications would dramatically improve it. I don't imagine those changes would be easy to make though. I couldn't afford one anyway(especially given the $AUS to $US exchange rate), so I built my own velomobile off of a KMX frame kit, and it has front suspension.