Ebike for kids

[Dixonk]

Hi there,
Wanting to buy parts for 20" and 24" to make a ebike for my kids. Without much prior knowledge or time spent googling or searching in general.

In my area I can buy tongsheng tsbz2b for around 240usd and I havent found anything similar in price for a hub motor that offers both 20" and 24" with a wheel, there is option to buy a hub motor but im not sure im capable of doing my own wheel and im not sure what the xost would be to have someone help with it.

What is your thoughts about setting up kids with a middrive motor? Is there any downsides compared to a hub motor?

Thanks!

 

[docw009]

That's true. Hubmotor prices have gone up and TSDZB prices have dropped such that I think the mid drive is a good alternative. In my opinion, the mid drive is less trouble to install, if your bike has a good chainline, No fooling around with where to put controller box, fiddling with a PAS sensor, or filing a 10mm dropout 2mm deeper for the 10x12mm axle.

The trade off is less power than a 500W geared hubmotor. You can get the rated controller amps with the latter. I usually use 20A controllers for my hubmotors and they pull 20A in bursts, My TSDZZ2 is more like 11-12A. Throttle is also not that strong in a TSDZ2, Finally, the kids need to know how to shift to make best use if the middrive.
There is a coaster brake version though.

For kids, having less power is good, They also will press the pedals with less force, and that limits power too. If you can still get the older controllers, you can put in OSFfirmware and detune the motor even further. The TSDZ2 will also run a while in smaller batteries, like a 36V6AH, which is nice. A hubmotor with a 15A controller might sag on that,

 

[neptronix]

The width of pedals of these cheaper middrive kits is extremely wide and it may be no good for a kid who doesn't have adult sized legs.

For the price of a typical chinese mid drive, you could almost buy two wimpy 250-500w kits with geared hub motors ( controller, prebuilt wheel, accessories ).

 

[Chalo]

Kids need real exercise a lot more than they need to go too fast for their skills and judgement. You'll be doing your kids a lifelong favor if you get them nicer pedal bikes that help develop healthy physiques and habits, rather than getting them motor toys that prematurely turn them into little car drivers.

My ex's nephew went down the latter road. At age 18, he nailed an SUV on his Sur-Ron and sustained a major brain injury. He spent weeks in a coma, and still can't speak almost a year later.

 

[E-HP]

Is there any downsides compared to a hub motor?

Shifting is required. On a hub it’s optional.

 

[floydr]

My ex's nephew went down the latter road. At age 18, he nailed an SUV on his Sur-Ron and sustained a major brain injury. He spent weeks in a coma, and still can't speak almost a year later.

Sorry to hear of his TBI. Agree about exercise is important for development of life skills. Knowing when to walk, run, bike responsibly is a skill best learned when younger.
later floyd

 

[neptronix]

Pretty horrifying!

Yeah i wouldn't give a kid more than 250w to be honest.

 

[Dixonk]

My kids ride motocross, 1000w is nothing to them. We do plenty of activities so im not worried about that but this is not the forum to discuss that, im here for ebike help, tips & tricks.

I can get a tongsheng 48v 500w for 240usd, I havent found anything similar in price for a hub motor, let alone two for that price.

Im abit worried now, do the pedals come further out with middrive?
And I dont want to play 240usd if the motor is weak. 250-500watts is nothing would most likely not carry my kids let alone me in any good speed in our hilly area.

 

[neptronix]

I'm surprised you can get a tongsheng for 240USD. Is that a direct from China price? if so, what are customs and shipping fees?

You can get complete small hub motor kits for $150-$200 shipped from the USA.
Example:
Yescom 20" Electric Bicycle Motor Front Wheel Kit 36v 750w

Mountain bikes for adults have usually 170mm Q factor, come with 170mm cranks.
A cheap chinese middrive will be in the ~210mm Q factor range, so this is more wide than average for an adult. It's really wide for a kid, and you may also not be able to get kid-sized super short crankarms for it.

 

[circuitsmith]

No propulsion assist for kids under 12, unless they're somehow disabled.
They can go just fine under their own steam. They need the exercise.
My opinion.

 

[E-HP]

When I started ebiking it was at a time where I hadn’t ridden my pedal bike for years. Ebiking got me out of the house and even with assist I was getting exercise, I lost weight, and my health generally improved.

If asked the question 15-20 years ago, I’d agree that it’s best for kids to pedal. My kids did. But now, with smart phones and video games, there are a lot of kids that trade any form of physical activity for time behind the screen, playing games and eating junk food. My opinion now is that it depends on the case. If an ebike gets them to be more active, then it may be a good thing, much like it worked for me as an adult. It’s a matter of choosing a setup that’s at a safe power level to match their level of experience, and good brakes.

I don't know what folks definition of "kids" is, so not sure if everyone is on the same page there, or even what the particular circumstances are, but it sound like the OP's kids have good experience with motorized vehicles. I grew up on a farm, so I had a lot more experience and freedom with motorized vehicles from a very young age than most, so everyone's experience varies. There are examples on this forum about ebikes builds for kids. Responsible kids. On balance, I've found there are probably a lot more dumb adults out there than dumb kids, which is why we all survived out childhood; that and luck.

Slow acceleration for 72v 2000w ebike.

Bike is actually pretty awesome for the young folks, and with a new rear shock it would be able to commute a full size adult It is really fast and silent as ever on flat ground and when my daughter is wide open throttle I cannot catch her on the 18s Kuberg which is pretty fast I rebuilt the...

endless-sphere.com

 

[Dixonk]

We live in Sweden so shipping cost is abit high, the tongsheng I found is from a site pswpower which is said to be safe to order from but they dont have hub motors for 20/24/26 wheels, they offer a 500w mxus for 50-100usd but those arent with wheels.

We get enough exercise, why keep mentioning that? Look, we want to have ebikes and abit of fun. Please stop replying if your intention is not to help.

I dont really care so much of top speed or speed in general, im more worried about torque and heard hub motors is abit bad on that end?

A 24/26 inch 1000w wheel setup with controller seems to be around 300usd, is this worth getting or are me and my kids going to be dissapointed?

If middrives makes the pedals that much wider im not sure thats an option.

We see alot of e-stuff where we live, scooters and what not and they are plenty fast! We want an ebike instead with enough power to come from A to B without its sagging midhill due to not enough torque or what not.

Thank you

 

[Papa]

Want torque?... HP?... Comparison?...Go here:...

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[Az.]

 

[Dixonk]

Im not looking to spend more than 2-300 max for a motor, is a 1kw Amazon motor worth 300usd or should I look else where? Im worried about tax,import and transport costs.

 

[E-HP]

is a 1kw Amazon motor worth 300usd

No, not if you're talking about a hub motor. I'd do with ebay instead for half the price and full kit.
e.g. 1000W 26" Rear Wheel Electric Bicycle EBike Motor Conversion Kit Hub Cycling 48V | eBay

20" : Voilamart 20'' 48V Electric Bicycle Front Wheel Ebike Motor Conversion Kit 1000W | eBay

 

[Dixonk]

No, not if you're talking about a hub motor. I'd do with ebay instead for half the price and full kit.
e.g. 1000W 26" Rear Wheel Electric Bicycle EBike Motor Conversion Kit Hub Cycling 48V | eBay

20" : Voilamart 20'' 48V Electric Bicycle Front Wheel Ebike Motor Conversion Kit 1000W | eBay

Oh, these looked like nice kits. Unfortunately they dont ship to sweden according to ebay probably super expensive if they would, like every other seller ive seen.
Doesnt seem possible to find any hubmotor at 200-300 shipped

 

[Az.]

Do you plan to install 1kW motor on a 20" bike for a child? That is insane.
What is the legal age for children to use e-bikes in Sweden?

 

[Chalo]

Do you plan to install 1kW motor on a 20" bike for a child? That is insane.

It's only insane to let a child ride it. An adult riding it would be physical comedy.

If I haven't already seen someone doing this in the wrong direction in the bike lane, I expect I will very soon. Entropy never takes a break.

 

[Dixonk]

Do you plan to install 1kW motor on a 20" bike for a child? That is insane.
What is the legal age for children to use e-bikes in Sweden?

Are you kidding me? My son does motocross a 1kw ebike is a joke.
There is no age of what im aware of, there is speed limits which I tend to follow.
He gets enough of that on the track, the 1000watt motor will be so there is enough torque (hopefully) to not be unfun and useful

If your intention is to not help, go troll somewhere else. Thank you kindly

 

[Chalo]

Here in Texas, irresponsible dads don't stop at motor toys-- they also go all in on guns for their kids. Because the way you do one thing is the way you do everything, I guess. Gotta raise the next generation of folks who make life harder than necessary for everybody.

 

[E-HP]

Are you kidding me? My son does motocross a 1kw ebike is a joke.
There is no age of what im aware of, there is speed limits which I tend to follow.
He gets enough of that on the track, the 1000watt motor will be so there is enough torque (hopefully) to not be unfun and useful

If your intention is to not help, go troll somewhere else. Thank you kindly

Be cautious. E-bikes don’t have a lot of horsepower, but the descending torque curve won’t be familiar to someone used to an ascending curve. I’d compare it to the old 2-stroke bikes, where the torque peak can catch you off guard and leave you on you back if you aren’t ready for it. Peak torque is at 0 rpm. My bike is more than 1000w, so if I apply any pedaling from a dead stop or even at 15mph, it will flip, unless I release the throttle quickly. When I ran my 1000w hub, it still wheelied if I applied more than light pedal pressure from a stop. You can get used to it, but with over 300k miles of riding motorcycles, and off-road when younger, I still get caught off guard. I usually try to make it look like it’s on purpose if there are people around.
Wheelies on purpose are fun; unexpected and it’ll leave streaks in your shorts.

 

[Chalo]

I recently replaced a failed controller on my fastest bike with a 60A "dumb" sine wave controller. The bike is slack angled and tail-heavy, so that combination caused unwanted whoopsie wheelies for the couple of miles the controller ran before it too burned out.

I replaced it with a 40A controller, otherwise identical, that doesn't lift the front wheel unrequested. Subjectively, the ride is just as exhilarating, but in practical terms it's safer, easier on all the components, and more pleasant.

I should probably specify that I'm the size of a group of children you'd have to count to be sure of their number.

 

[Dixonk]

Be cautious. E-bikes don’t have a lot of horsepower, but the descending torque curve won’t be familiar to someone used to an ascending curve. I’d compare it to the old 2-stroke bikes, where the torque peak can catch you off guard and leave you on you back if you aren’t ready for it. Peak torque is at 0 rpm. My bike is more than 1000w, so if I apply any pedaling from a dead stop or even at 15mph, it will flip, unless I release the throttle quickly. When I ran my 1000w hub, it still wheelied if I applied more than light pedal pressure from a stop. You can get used to it, but with over 300k miles of riding motorcycles, and off-road when younger, I still get caught off guard. I usually try to make it look like it’s on purpose if there are people around.
Wheelies on purpose are fun; unexpected and it’ll leave streaks in your shorts.

Thank you for your explaination. I appreciate it
We have a 250watt bike at home and its very bad and hardly gets us uphill and we have had a 1000watt kids bike that wasnt any good either so our experience is from that.

I appreciate everyones concern but im here for help.
Wether a hub motor brings enough torque or if we should go for a tongsheng tsb, I dont have any experience so thats why im here asking

Speed limit here for assist is 20km/h i believe or 25 and I have no intention of going above that, there is no reason what so ever, we have plenty of hills here so we need that power to bring us uphill.
Thank you

 

[E-HP]

Thank you for your explaination. I appreciate it
We have a 250watt bike at home and its very bad and hardly gets us uphill and we have had a 1000watt kids bike that wasnt any good either so our experience is from that.

I appreciate everyones concern but im here for help.
Wether a hub motor brings enough torque or if we should go for a tongsheng tsb, I dont have any experience so thats why im here asking

Speed limit here for assist is 20km/h i believe or 25 and I have no intention of going above that, there is no reason what so ever, we have plenty of hills here so we need that power to bring us uphill.
Thank you

It's all about the battery. A motor will take as much as the battery can provide, until it get's too hot. Get the best battery you can afford and a cheap kit, then you have an upgrade path, if you decide to let them have more power later. If you have steep technical climbs where you need to ride slowly,, the mid drive is the way to go. It will also require more pedaling, so good for fitness.