solarbike

Way cool!!  I think I would opt for the panels without the other hardware. I would lose out riding directly into the sun that way (with the panel on or over the rack) but this would save much weight and awkwardness (and danger from low branches!).

I have a 250w motor on my Dahon Vitesse. The motor and battery weigh in at 3.3 kg. Add the panel to that. Doubling the weight of the folder makes little sense. (The roll-bars on a full sized MTB might be good--use them to hang wet-weather protection in the winter.)

This motor comes in 80mm and 100mm hub widths. Placing the 80mm on a rim and this on the Vitesse means stretching the forks apart. My bike has steel forks. Tern are likely quite similar so this kit would not go on most of them with their aluminum forks. Since the fork bears the brunt of bumps and strains, I would want to buy a Tern only with chromoloy forks whether or not I go for the motor.

More questions for Frank:

Panel output--can it drive the motor bare (probably not)? On an average Summer day in Germany, for example, how much additional range would the (newer) panels get me. Battery is 91whr and its plugin charger takes 100 min.

And the kicker: the price? (Then, again, these ebike motor-kits are way too expensive anyway, so if I spring for that, what's a few more Euros?)

Might contact freedomebikes.com. They might want to distribute these kits!

Better motor kits are 36v (some even 48v now). Mine is 36v. 91 whr battery will power the motor flat-out for 20 min but of course, it is not used that way. In mixed riding, one can go 15km. Since the batteries are small and only weigh .95 kg, one can parallel a second battery. Less expensive is to recharge at work (though batteries do have a finite number of charge cycles lifetime).

Can a 36v solar array of reasonable power and weight be set up? I still cannot see riding with that whole rig, would prefer to place the array above the rack. Depending upon the weight of the array, a less obtrusive stand might be practical.

The parked bike is solar-recharging on a sunny day. However, it says quite loudly: steal me! Or at least the battery and solar panel if the bike is chained securely. Something to be considered, unfortunately.

The chopper, based on a full-sized MTB, might be the way to go. One is less worried about weight on these than on a folder.

Conrad does have 18v arrays so could make 36v as well. A 1.5 amp array would give maybe a 15% range boost in best sunlight. Would charge the freedom ebike battery in two hours. One would need to consider cost vs benefit. A second battery doubles the range, works rain or shine, and would cost comparable or less then the solar panel plus its hardware. A spare charger at work on in the school locker is a very cheap alternative as well.

The 90cm+ array are not a good formfactor for a folding bike (they have 1.5m ones as well!). Maybe on the chopper. A roof made of two of these would be practical, could feed your motor 3A which would give a 30% range boost or quick-charging at noon. Again, cost vs. benefit. Photovoltaic cells are still very inefficient and though these thin, flexible cells are light, they still need a lot of area to deliver the power and are not cheap.

Again, contact freedomebikes. They designed the lightest but quite effective electric assist kit and might work with you to come up with an effective solar kit for folders as well.

Looking forward to further developments!