Hi,

I have a single speed folding bike that I am considering motorizing (dahon boardwalk S1). Are there any good kits for folding bike frames like the S1, that aren't very difficult to install?

Thanks

You do realize that this will make the bike REALLY heavy and not easy to carry right?

Yes I do. My folding bike is stored in the trunk of my car and is not carried anywhere by hand

I seem to recall there were some hub motors that were wound for small wheels mostly for recumbents.

BionX would probably be your best bet. I've seen a few of the smaller wheeled Dahons with BionX kits.
https://www.bionx.ca/en/

My brother has a Brompton M6L with Crystalite 209 motor (Nycewheels conversion) and it is HEAVY at 34.5lb w/o the battery. Add about another 4 lb for the 10Ah battery. I tried another Brompton M6L with Freedom Ebike conversion (Tongxin motor) and the whole thing with the 5Ah battery weighs about 30lbs. The Tongxin motor has much better freewheel (less drag) than the 209 Crystalite motor.

Just about any kit (Bionix, Crystalite, Falcon) will have a 20" wheel motor. Most of them want to put the batteries in ugly bags that you hang off your rear rack. The E+ system replaces the front wheel with a special hub battery. Nice! Neat. Elegant. Expensive. I think its worth it but I would want to use a donor folder higher up the food chain than a Boardwalk. Just saying.

H

Check out Predeco they have a clean system. maybe they would sell you the components. Their bikes are way less and assembled in the US.

Dahon's generally won't accept a normal front hub motor as the dropout spacing is only around 79 mm, and most front hub motors are 100mm. However, there is one small hub motor (nominal 500watt?) that I have - the Crystalyte 209, which drops into a Dahon nicely - it is designed for folders. I have mine on a Speed 21 Dahon. It is a brushless direct drive hub motor and has quite high RPM per volt so it can get your bike to well over 20mph. The torque of the motor is reasonable, but not "high". It can get warm with 1000 watts sustained into it. I'm running it with a sensorless controller from bmsbattery.com. It was easy to fit the bike. You can get them from itselectric.ca (in Calgary, Alberta). The "normal" hubs like the Crystalyte 40x or 50x series, or Nine-Continent or GoldenMotor wont fit in the front fork. I wanted to preserve my rear 3x7 Sachs gearing so I went for a front motor solution. It works well. The 209 weighs around 8 or nine pounds as I recall. The 206 is even faster, I wouldn't use that motor. Apologies awdnut, I didn't see your note on the 209.

there are some folding electric assist bikes already built that way ,
to name some, modest priced, e-Moto, another import.

so a cost advantage over the retrofit is right there.

Yes, still no free lunch .. motor and battery will be heavy.

Is this the idea of what you are looking for? This on is a rear conversion kit but the frontkit will work as well. The geared motors are much smaller diameter and little lighter as well:
https://www.ampedbikes.com/forum/view...=folding#p3424

Chvid,
Your post answered some of my questions. I'd like to put a 20" front hub motor (BMC V2-T ) on a bike, and was considering putting it on a folder. I am committed to this hub motor because I already have it and it provides sufficient torque to climb hills here in Seattle. It is geared, has a top speed of about 15mph on a 20" wheel with a 36V battery, and has practically no drag when turned off.

For me, a 20" wheeled bike makes the perfect ebike since I am looking for torque at low speed. I could care less about motoring around at speeds over 15mph.

I was interested in a used Dahon Speed that I found, but have lots of question about possible non-standard specs on the Dahon, including the front dropouts (for the hub motor), and the bottom bracket (for a special crankset I want to use). I believe the Speed has a steel fork which I hoped was strong enough for a hub motor. Of course, a motor defeats the major benefit of a folder, but there just aren't many non-folding 20" bikes out there.

Robert