A lightweight folding bike.

[harryS]

Around January, I got interested in a folding e-bike and looked at some inexpensive models on amazon for around $600. Perhaps I should have bought one, but I decided to kit one up, using the Downtube Nova. This was $279 shipped. 7 speeds. About 24 pounds.

I ordered a Q100H 350W motor from China in January. That was $140 shipped. I could have had it for $250 shipped with a 20" wheel, but I chose to buy a 20" rim and spoke it at home. The wheel parts cost me $60. Took me two evenings total to do the spokes. I did it wrong the first night. Rode it around for a week. Tore it apart and did it again.

I used a 250W controller I bought on ebay a year ago for $25 with a PAS sensor. Also had a $10 thumb throttle, and some extra e-brake levers. Those would be about $20. So total for electronics was $55, call it $60.

Today. Bike is still in progress. I added a $12 rack, cut down to fit 20" wheels. The controller is under the rack. A 36V battery is in the bag ($3) . I will spray paint the silver controller black.

About the battery. I own a number of small batteries. Shown is a Luna 52V mini (350 watt-hr), two 36V weedwhacker batteries from my chain saw and weed cutter (80 and 180 watt-hr), and a custom 36V (300 watt-hr) battery.

Per a suggestion from forum member GeorgeS, I asked Shawn McCarty about a 30 cell 10S-3P custom battery. He gave me a nice price and that's the custom battery you see.

I can get bigger seat bags, maybe, but only Shawn's battery fits into my bag. This is before I shrink wrapped it.

With the current controller and 36V, the folder will do about 18 mph max. With a similar controller and 48V and 52V, I've seen 20 and 22 mph. The motor takes only about 6-8 watt-hr/mile at 14 mph, so I expect over 25 miles with the custom battery. Plus the bike is light enough that it pedals like a regular bike.

I think 18 mph is good enough for this little guy. The motor adds 4.8 pounds, and the battery is 3.3 pounds. I added that much to my belly this winter doing nothing, so I better get riding again.

I am around $750, more than what an Ancheer would cost on Amazon. The Nova frame is a nice bike for the price though, and probably a lot lighter.

There's a second folding bike for my wife coming. It has full suspension. Will be heavier. I'll use one of the existing batteries for it.

 

[Shoestring]

That's a nice compact build, HarryS, I like it!

 

[SuperGoop]

You may need to get fenders and/or really waterproof all the electronics. Nice build!

 

[harryS]

Here's my wife's bike. Downtube FS8($329), which has full suspension. I added the same Q100H motor. The original wheel had an 11T cassette. I used a DNP Epoch 11T-34T freewheel to keep the gearing. Otherwise, the 14T freewheel that comes with kits would have me spinning the pedals like mad at 12 mph.

Controller under the rack, as per the earlier conversion. I sealed the edges of the box with extra silicone. I'll get fenders later, except that I can get a cheap folder bike with fenders for the price of four fenders.

I also put on Kenda 100 psi recumbent tricycle tires. The bike rolls great. Rides nice.

I found a bigger bag on Amazon that holds the Luna Mini. It hangs securely off the seat. I haven't dressed up the red/black battery cable yet. Will change it to black when I get some silcone wires. I also might combine the LCD, throttle, and brakes (7 wires) into a single cable, which would be about the same diameter as the brake cable. This would hide the wiring better. The Q100H supports a speed sensor in the motor that the controller can use for mph.

I can power it with 36 volts or go up to 52 volts. Throttle only tops out at 18 mph on 36 volts, and 24 mph on 52 volts. Above 18 mph, the pedals spin pretty fast in pedal assist. They spin insane fast at 22 mph. My wife will never go above 14 mph on 36 volts. I will not go much faster. It's a folding bike after all. My wife really likes it for riding around the local bike paths.

I'll want to put this more versatile KT-controller on my yellow bike too. It has 5 PAS levels, with torque simulation. It feels good at 7 mph, all the way to 20 mph.

 

[robin-d]

I'm very interested in picking up one of these bikes also.. how important/useful is the suspension to the ride, especially at speed?

any recommendations on whether i should just go with the nova, front susp only, or full? i'm thinking about pairing it with a 9C motor @ 48v.

 

[harryS]

Folders, by their nature will rider harder than a bigger tire bike. I'd have to go with the full suspension.

 

[robin-d]

thank you