Schwinn Cruiser Supreme electric build

Hi all,

I know the electric section on here gets a lot less traffic, so figured I would post here too. I recently built an electric hub motored bicycle using a 1999 Schwinn Cruiser Supreme. I think it turned out great! I still need to do some cosmetic work and fab a protective housing for the batteries, thinking a faux tank over the upper batteries, etc...

This is a link to the build thread over in the DIY electric section: Schwinn Cruiser Supreme with GM 901 rear hub

Here is a picture of the bike before electrifying, along with a larger Schwinn Heavy Duti that I was originally going to use. I found that the Heavy Duti had cracks in the frame, needed the chainstays spread, etc, so went with the smaller geared Cruiser Supreme.




And some after pictures:









Definitely a different world than gas bikes. I worry less about the bike shaking itself apart and more about range, LOL. As is, my longest errand run is 6 miles roundtrip, so I just went with 10AH of battery. As is, if I peddle comfortably and motor at the same time, keeping the speed to around 20 MPH I can get 30 - 40 miles. But since I am lazy, rarely pedal, and like speed, keeping closer to 30 - 35 I get closer to 15 miles.

The fastest I have gone so far is 47 MPH, but the motor would melt down pretty quickly if I tried to sustain that speed since it is a not a truly heavy duty motor (rated for 1,000W and at top speed I was pulling 3,900W!).

Thanks Dan, it was a fun build and a blast to ride. A lot of the electric guys go with mountain bikes, but since I knew this was going to be road only (and occasionally grass), I figured a cruiser would work nicely.

When you start planning your electric build, you will want to check out the endless-sphere ebike forums. That is where I got a lot of the info I needed for my build. There is a ton of info there (like here), so it takes a while to sift through. I will also be more than happy to answer anything that I can.

I went with RC lipo batteries since they are cheaper and lighter per watt/hour than most of the other lithiums. BUT... they are also touchier with respect to handling and charging and do not take a lot of abuse before they burst into flames. Overcharge them, poof into flames. Over-discharge them, then when charged next, poof into flames. Drop one from more than a couple feet or puncture one, poof into flames...

My setup uses twelve 4s 5AH batteries (1s is 3.7V nominal, 4.2V fully charged). I wired them into a 24s 10AH pack, which pushes the raggedy edge of my controller and motor's limits. I did that so I could opt to upgrade to a more powerful motor with little effort in the future.

LiFePO4 are another popular lithium choice and are dramatically more durable (but can still poof if abused), but cost more and are bigger/heavier.

For example, my lipo pack at 24s 2p 10AH lipo, or roughly 89V (99V fully charged). But I can easily rewire it to a 12s4p pack, roughly equivalent to a 48V 20AH pack. That cost me about $325 shipped. An equivalent LiFePO4 battery will run around $750 - $800 shipped. But that includes a battery management system (BMS) built in that helps prevent overcharging and undercharging.

With my setup, I charge my batteries with a Hyperion 1420i hooked to a PC, so I can visually see the health of each battery so I know if one is going bad, and it also shuts off when charging is complete. And I ride with a Cycle Analyst bike computer which displays how much battery capacity I have used, so I have a good idea of when I need to charge, and a buzzer on each battery so should they get to a critical state if I am not paying attention, they yell loudly

So while I love lipo batteries, they require you stay on top of them or face a house fire. Or worse, a crotch fire. If I were to build a bike for someone else, I would definitely not opt for lipo. The A123 amp20 LiFePO4 cells look very promising, but $$$.

Sealed Lead Acid batteries (like those used in electric scooters) are safe and cheap, but voltage sag easily, last only a year or two usually, and are heeeeavy.

But do not get me wrong, it sounds like a big pain but really is not. The tradeoff is a bike with better acceleration and top speed than my China Girl, cost about the same after all of the upgrades, and does not vibrate and is very quiet.

But that initial sticker shock and range scares off many.

Thanks for the compliments fellas!

I do plan on some sort of covering or protection for the batteries. I like the raw look of the exposed wires, a mad scientist's ride! But some sort of crash/wire snag protection is in order.

I was thinking of going with smoked plexiglass so you could still get a peek behind to see the goods, along with CPU fans to help keep the controller cool. Along with a faux tank to cover the upper portion to match...

I also ordered some new handlebars yesterday, the Nitto B617. I had planned on getting them eventually, but settled for flipped bars for now. My wife saw it yesterday and said "Did you buy that handlebar like that?" I told her no, I just flipped the stock one since the bars I want are $50. She said "I don't like it, you need to fix them."

I interpret that as permission to buy the new bars, right???? Hey, it was her idea!

Installed the new bars last week. Getting used to the more upright riding position and am really liking them.

And I had to know... I just had to...

I reprogrammed my controller to run 45 amps (it spiked to 52A at one point in my run), put on my motorcycle gear, and went for a high speed run. I backed off at 52 MPH... I just wanted to see 50 and not turn my motor into molten lava.

That is the first and last time I try that with this setup, but I had to see. I took my phone with the GPS turned on to verify the CycleAnalyst's speedo reading.



I had to pull around 4,500W to get there, through my little 1000W rated motor so you really do not want to do that for long!

I think it ceases to be a bicycle as soon as I flip the battery switch on. At that point it becomes an illegal motorized bicycle. With the switch off, I figure it is just a heavy bike with a lot of decoration Now, if I use my CA to limit the wattage to 750W and speed to 20 MPH (which the CA can do), then it is a completely legal electric motorized bicycle. But at those power levels, I might as well just pedal... LOL

As far as the total weight, not quite sure. I weighed the motor/wheel/tire combo at 26 lbs right after I laced it up.

So estimates would be:

- Motor/wheel/tire: 23 lbs
- Bicycle: 40 lbs?
- Batteries: 528g x 12 = 6,336g = 14 lbs
- Freaky heavy layback seatpost = 3 lbs

So around 80 lbs? That feels about right. The bike is liftable, but you would not want to carry it very far.

Moto said:

Thats awesome! What tires are those? REALLY nice bike - the first electric that ive really connected with.

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Thanks Moto, I really like the way it is turning out. So much fun to ride.

The wheels are Weinmann DH-39, and the tires are 26" x 2.4" CST Cyclops Pro. Pretty much a poor man's Hookworm? When I bought them they were $13 shipped each, looks like they are up on $19 shipped on Amazon right now.

They are big and beefy. Here are pictures of the rear compared to the stock 26" x 2.125" rear that was on the bike originally:

phatcruiser said:

Sweet ride. Electric bikes are so cool. How long will the batteries last, at your average rate of use?

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That really depends on how I am feeling, lol. If I want to get some exercise, I can comfortably pedal and keep up with the motor to 20, using the motor enough to not get winded or sweat. At that rate, I burn about 0.25 AH per mile, so about 30 miles before I start sweating to charge.

But more often I find myself minimally pedaling from a stop and cruising around 25 - 30mph, riding the bike like an e-motorcyle. In that case it is closer to 0.5 AH per mile, so comfortably charging at 10 miles (50% discharged) or could push it to 15 miles without worrying about over discharging the batteries.

I could easily add more capacity for range, but since most of my trips to the store and errands are only about 2.5 miles round trip, this setup is working well.