4 Bike 500w Rear Hub Motor Builds from Greenergy

BADsDAD

New Member
First post here and I am just learning about all this, so please don't beat me up too badly. :cool:

I just ordered 4 Bafang kits off ebay from Greenergia to build ebikes for the family - me, wife, 2 boys 8 and 10yo.

For my 10yo, he has a Specialized Hotrock 24, but they only offered wheel kits in 20/26/700c. So I bought a 20 for my 8yo, 2x 26's for wife's current Cannondale and for a bike for my 10yo and a 700c for my Rockhopper 29.

I am looking for a decent bike to buy for my 10yo who can just now fit on the Wife's 26" with a 16" frame.

Is there a recommended bike for this kind of build that will not require a lot of extra parts? i.e. 44mm bolt disk brake, cassette style freewheel etc? I'd like to keep the cost around 2-300 for the bike if possible.
Also, as I have never done this before, any advice would be greatly appreciated.

If anyone is curious, the ebay kits are item 352721969952. All cassette, all 500c except mine which will be 850c, 17.5ah for me and wife and 12ah for both kids (supposedly Samsung 35ET and 29ET) in HL mount.
 

harryS

Well-Known Member
You'll need a bike with 135mm axle spacing, which is your typical mountain bike, width. These kits often run a little bit wider/narrower. You can usually move the washers around to avoid having to spread an aluminum frame. Doesn't matter too much with steel.

Maybe a 20" folder? Then the larger folks can ride it and it grows with him. My wife rides a Downtube 8FS is full suspension , and I have a bare Downtube Nova, which I converted to electric. Thanks to tariffs, both are $70-100 more than when I bought them at $430 and $320. Battery placement is tough with these though.
 

Thomas Jaszewski

Well-Known Member
I don’t see torque arms in the list. Perhaps I missed them. If I didn’t please do use them. At least one on each bike. 29E and 35E batteries aren’t a good value. As long as they are as claimed. Seems like nice kits. Have fun!
 

BADsDAD

New Member
yeah, battery placement will be tough on the little Hotrock as well. I mean, I know big box store bikes are crappy, but I can't help but wonder if I should buy both of the boys new bikes just for this conversion project and leave their Hotrocks alone for now. I at least have to buy a 26 for my 10yo, but man the big box store bikes seem worse than I remember them being. I had a big box Mongoose Pro bike about 13 years go that was Alivio and half decent Suntour forks all aluminum and ran for years with not too many issues, also made in Taiwan. The ones I looked at yesterday seemed to be much much more cheaply built.
 

BADsDAD

New Member
Thanks! I was just watching a vid on the torque arms and will order some if the are available. The type that connect to the caliper mount would work on at least two of the bikes. If I have to fabricate the others, I can do that, but I totally get why they are required.

29E and 35E aren't a good value? It maybe a little late now, but what are a better value?
 

AHicks

Well-Known Member
Not to minimize all the other choices, but for my own purposes I would not consider a bike that didn't have disk brakes.

I ended up with a couple of new Schwinn bikes from Walmart for my first builds. About 200 apiece. One was just OK, but the other seemed a much higher quality build. Even had the rear mounted kick stand.
 

stanmiller

Member
First post here and I am just learning about all this, so please don't beat me up too badly. :cool:

I just ordered 4 Bafang kits off ebay from Greenergia to build ebikes for the family - me, wife, 2 boys 8 and 10yo.

Is there a recommended bike for this kind of build that will not require a lot of extra parts? i.e. 44mm bolt disk brake, cassette style freewheel etc? I'd like to keep the cost around 2-300 for the bike if possible.
Also, as I have never done this before, any advice would be greatly appreciated.
These kits you ordered are made by 'Bluenergy'. They are good kits and include torque washers.

I have over 2,000 miles on my Electra Townie conversion with a Bluenergy kit.

And my wife just crossed 200 miles on her's.

Both bikes are equipped with upgraded rim brakes. I started out with a disc brake on my Townie but swapped back to a rim brake for less maintenance.
 
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BADsDAD

New Member
Both bikes are equipped with rim brakes. I started out with a disc brake on my Townie but swapped back to a rim brake for less maintenance.
[/QUOTE]

Thank you! So the rims are appropriate for rim brakes without any removal of the paint from the rim? What I mean is, should I plan to remove the paint from the braking surface manually?
 

stanmiller

Member
Thank you! So the rims are appropriate for rim brakes without any removal of the paint from the rim? What I mean is, should I plan to remove the paint from the braking surface manually?
The Bluenergy rims are disc brake only. The painted surface where the brakes would contact is not suitable for braking.

You'll need to move the motor to a rim brake compatible wheel like this one by Alex.


For my wife's bike, I bought a motor-only kit and paid a bike shop to build a wheel. For my bike, I removed the motor from the Bluenergy rim and built a new wheel myself.
 
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BADsDAD

New Member
Well great.. Now I am thinking I should just buy 3 bikes for the conversion as mine is the only one with cassette and disc brakes.. sigh..

I'm ok with that for the 2 26" bikes, but I'm not sure I've seen a disc 20". What problems did you have with the conversion kit?
 

stanmiller

Member
Well great.. Now I am thinking I should just buy 3 bikes for the conversion as mine is the only one with cassette and disc brakes.. sigh..

I'm ok with that for the 2 26" bikes, but I'm not sure I've seen a disc 20". What problems did you have with the conversion kit?
DIY conversions are fun projects and rewarding, but be prepared for some hidden costs. When I bought my first Bluenergy kit on Amazon, I assumed 'disc brake compatible' meant the wheel was for rim brakes but also compatible with disc. Not so - disc brake only. The ebay listing specifies, "... which is compatible with the disc brake"

Battery mounting and size can also be an issue. Are the bottle mounts too high, low, or just right. Will one need an adapter to shift the location of the bottle mounts? Does it interfere with the front derailleur?

The kit includes new brake handles with integrated motor cut-off switches. Typically, you'll want to use those. If the donor bike is equipped with trigger shifters with integrated brake levers, you'lll need new standalone shifters or attach a third party cut-off switch to the existing brake levers.

Is there enough room on the handle bars for the thumb throttle, shifters, brake levers, and so on?

Bluenergy offers three types of pedal assist sensors. My wife's bike and my Townie have a PAS1 installed. My Mongoose Envoy uses a PAS3 as the PAS1 was too small for the crank axle.


Lastly, a 500w motor will get-up-and-go and top out at 28mph. For a kids bike, 250w would be better (safer). Though not offered in the eBay listing, Bluenergy does sell a 36v/250w kit.


@Browneye is converting his wife's Specialized Roll with a Bluenergy kit as we speak. Maybe he'll jump in here.
 
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Browneye

Active Member
Yes, I ordered the 48v 500w hub kit from Greenergia - an Amazon seller. They sell the 'Bluenergy' products whom also sells on AliExpress. It's a bafang kid and hub they lace to your wheel size, but yeah there are a lot of little details that go into making this work and StanMiller was a big help in convincing me to try the DIY route. I'm pretty handy, having done a ton of similar type projects.

I was going to do my own bike as well, but it's a carbon-forked superlight with v-brakes, and in the end it got to be where it was going to cost nearly as much as just buying a purpose-build ebike. So that's what I did, now selling my nice pedal bike on craigslist.

I went ahead and ordered from Amazon for their buyer-protection features, and the amazon seller Greenergia has a reasonably good review reputation, and a domestic phone number for tech support and warranty claims. They've been pretty responsive over the course of my order, but we are still WAITING. And waiting!!

I paid an extra fee for expedited shipping. So the battery came pretty quick - about 10 days, but we're still waiting on the parts kit. It's been two weeks and they're saying it's liable to be another week or two before it gets here - China mail hands off to USPS. I have tracking now so I can check on it, but I really thought we would have everything by now.

In OP's case I would have just bought Rad Power or Juice bikes, or Aventon or something. Would have saved a TON of headaches and you would be out riding on them instead of fiddling with trying to get everything to work. Plus a warranty to ensure everything stays working. You build them you're on your own. And it's not much cheaper.

In my case the wife's bike is a perfect candidate for a conversion - a Specialized Roll Sport - it already has disc brakes, good battery mounting location, perfect frame geometry, and ebike type fat tires. It's still going to end up costing nearly a grand, and the bike by itself was about $600. You can buy a pretty darn nice brand new ebike for that!

Anyway...subscribed now...where's the popcorn. 🤣
 

BADsDAD

New Member
Man, thank you much for the experience and info. I used to be an auto mechanic and have done a fair amount of welding and fabrication and have my own shop (welders, plasma cutter etc).

What I'm not though, is a bicycle mechanic, but I felt like this would be a good project for me and the boys to work on together and something that will be great fun once completed as well.

It's not so much the budget as I don't really want to waste money by going the wrong direction on the existing bikes and have more in them than I could have just bought a BD bike for.

The Motobecane 400HT seems pretty close to something I could make work for the wife and older Son (26" wheels, disc, cassette) , but naturally they are out of stock in the sizes I need.

I'd like to reply to some of your points as any experience you can share is greatly appreciated:


DIY conversions are fun projects and rewarding, but be prepared for some hidden costs. When I bought my first Bluenergy kit on Amazon, I assumed 'disc brake compatible' meant the wheel was for rim brakes but also compatible with disc. Not so - disc brake only. The ebay listing specifies, "... which is compatible with the disc brake"

Foolishly here, instead of asking, I saw the same kit on Amazon where someone had asked if the wheels could be used with rim brakes and another user answered yes. I shouldn't have paid any attention there as they sure don't appear to be compatible.

Battery mounting and size can also be an issue. Are the bottle mounts too high, low, or just right. Will one need an adapter to shift the location of the bottle mounts? Does it interfere with the front derailleur?

I totally expect to have to fab up mounting on the 20" bike as there is no possible way I could fit it inside the frame. Maybe above the crossbar or below, but no way inside.

The kit includes new brake handles with integrated motor cut-off switches. Typically, you'll want to use those. If the donor bike is equipped with trigger shifters with integrated brake levers, you will either need to buy new standalone shifters or attach a third party cut-off switch to the existing brake levers.

For this, I ordered every kit with hydraulic brake sensors as they seem compatible with any sort of brake lever as long as there is room to attach the sensor and magnet.

Is there enough room on the handle bars for the thumb throttle, shifters, brake levers, and so on?

Not sure the boys will get a thumb throttle, they may get PAS only if my wife gets her way. She doesn't want the thumb throttle either.

Bluenergy offers three types of pedal assist sensors. My wife's bike and my Townie have a PAS1 installed. My Mongoose Envoy uses a PAS3 as the PAS1 was too small for the crank axle.


Thank you, I need to research this as I don't want to wait another couple weeks or more for another model PAS.

Lastly, a 500w motor will get-up-and-go and top out at 28mph. For a kids bike, 250w would be better (safer). Though not offered in the eBay listing, Bluenergy does sell a 36v/250w kit.

My logic with buying all 500w motors was that I was thinking I could just limit the speed in the 500c controllers to something like 15mph. And the 500w would give them something to grow into as they'll be teenagers before I know it and I could just move the motors to new wheels if necessary. I saw so many reviews stating that the 250w was pretty weak and was afraid of disappointment there.
My worry would be torque application and whether that curve can be limited as well. Still have some research to do there, but limiting top speed is my big concern unless I am way off here.



@Browneye is converting his wife's Specialized Roll with a Bluenergy kit as we speak. Maybe he'll jump in here.
 

AHicks

Well-Known Member
Nobody wants a thumb throttle, until they try one...

With just a little mechanical ingenuity, and a lot of patience, I'm sure you can get the job done here. Just take it one bike at a time.

As far as mounting anything in the triangle area of the bike, my advice would be to keep the battery as low as possible, and look into nutserts to use for mounting points.
 

BADsDAD

New Member
Well, I know I want the thumb throttle! But from what I understand, Texas has recently started classifying using the 1-3 level and given that we'd like to be able to ride parks and trails, we may be restricted soon to using only class 1 (PAS only and motor limited to 20mph) bikes in parks. I believe Arkansas has something similar and we'd like to ride those parks as well. I also read something about all ebikes made/built after Jan1 2020 having to have a "class 1/2/3" sticker displayed, but I have no idea how they would determine the manufacture date was after 1/1/20 out in the field.
Then there was this article about National Parks: https://www.nps.gov/orgs/1207/ebikepolicy.htm
 

BADsDAD

New Member
Just got word back from Greenergy that the 20" wheel does support a rim brake but the 26" and 700c do not. That helps immensely as I was not looking forward to adding a disc to a 20" kids bike.

After talking to the boss last night, she just wants 2 sets for bikes for her and the kids. ebikes and regular bikes. She has good logic though as we often go to campgrounds where ebikes would be totally inappropriate.

So now I am on the hunt for 2x 26" and 1x 20" donor bikes. Looking at some Trek 3500s and such on CL, they appear to have disc mounts already and are dirt cheap donors (~100-150$).
 

harryS

Well-Known Member
Wish I could weld. I would tacked on some caliper mounts onto my steel fatbike. I had to buy new front forks and rigged an adapter on the rear.

There's a lot to be said for a steel frame bike when doing a conversion. Market value is less if you are looking for a donor.You can add holes for battery mounts w/o worrying about weakening a frame. Might get away w/o torque arms on the rear.

Keeping the old bikes is a good idea if you have room. By next year, you will have converted them to electric too. Once you have a battery, it can be moved around. Motors are cheap.
 

Browneye

Active Member
Just got word back from Greenergy that the 20" wheel does support a rim brake but the 26" and 700c do not. That helps immensely as I was not looking forward to adding a disc to a 20" kids bike.

After talking to the boss last night, she just wants 2 sets for bikes for her and the kids. ebikes and regular bikes. She has good logic though as we often go to campgrounds where ebikes would be totally inappropriate.

So now I am on the hunt for 2x 26" and 1x 20" donor bikes. Looking at some Trek 3500s and such on CL, they appear to have disc mounts already and are dirt cheap donors (~100-150$).
Your local bike shop will lace any wheel on a hub that you want. If all else fails, just build the assembly you need.

I would not convert a bike to disc brakes - there are no brackets for the calipers to mount to and in many cases the frame or fork are simply not designed for those kinds of stresses.

ebikes.ca in Canada will build you anything you want with their hubs - they have a mini-250watt geared hub that would be perfect for something not too go-fast.
 

BADsDAD

New Member
Wish I could weld. I would tacked on some caliper mounts onto my steel fatbike. I had to buy new front forks and rigged an adapter on the rear.

There's a lot to be said for a steel frame bike when doing a conversion. Market value is less if you are looking for a donor.You can add holes for battery mounts w/o worrying about weakening a frame. Might get away w/o torque arms on the rear.

Keeping the old bikes is a good idea if you have room. By next year, you will have converted them to electric too. Once you have a battery, it can be moved around. Motors are cheap.
Thank you, I think this is the way to go. I also have a spool gun and can weld aluminum if necessary, though the paint may not look so great afterwards.