Build electric kids bike.

[EspenT]

I want to build an electric bike to give my daughter as a two year birthday present. I think it is a bit to expensive to buy a bike like the oset 12.5 just to see if se like to ride. http://osetbikes.com/us/oset-bikes-en-US/oset-12-5-racing-en-US/

So my plan was to use something like the bike underneath and add a small hub motor wheel to it. What is a suitable motor to use? I´ve measured the dropout spacing on a bike(not the same as on the picture) and it was 115mm.

 

[amberwolf]

I certainly appreciate the thought you have of introducing her to ebikes really early...but:

Are you going to have the throttle on a cable for you yourself to control?

If not, I think it is a spectactularly bad idea to give a two-year-old a self-driven bike, as they could be running over their own leg and not know how to stop the bike--even at only 0.5mph they could still be injuring themselves, and you might not be able to stop it before they are hurt worse, and they are unlikley to be able to follow your direction to stop.

 

[The fingers]

That does sound a little over the top. :wink: My daughter is 17 and we won't let her even have a skateboard. She can ride a bike or go roller skating if she wants; but as long as she under our roof we set the boundaries. If she doesn't like it, she doesn't get to double date with us and her boyfriend. :lol:
Or, if we have to; we start taking away her iphone, then also her laptop and slate, then ipad, and so on. :lol:

 

[r3volved]

What about a friction drive with a push button on-off momentary throttle? Add an inline potentiometer to your button and you can lock the throttle output.

...for a kids bike, you could probably make the whole thing out of an old powertool...including swappable battery.

 

[Mundo]

Perhaps you should consider something more age appropriate......

http://www.walmart.com/browse/toys/ride-on-toys/4171_133073_5353?cat_id=4171_133073_5353&facet=brand:Kid%20Motorz

 

[Syonyk]

This is a terrible idea to give to someone who either can't yet ride a bike or can barely ride a bike.

Don't do it.

 

[DAND214]

2? TWO? Daughter?
Are you sure? Not under my roof!

Dan

 

[Dauntless]

AN EXCEPTIONAL opportunity for the mechanically-minded person to exercise his ingenuity and creative ability is afforded in the construction of miniature motorcycles for youngsters ranging all the way from three up to eight or ten years of age.

When complete, these tiny motorcycles operate exactly like their larger brothers, which may be seen in the hands of sportsmen and motorcycle policemen. The tiny engines propel the little machines along at 35 or 40 miles an hour, yet are easily controlled at a twist of the wrist by regular motorcycle throttle and spark grip.

Needless to say, the youngster who is in possession of one of these custom built motorbikes is the envy of all his friends, and his grownups may feel that they are performing an educational service for the youngster in teaching him so early in life to control powerful forces.

 

[EspenT]

I value all of your concerns. However my question was not about when to introduce children to electric bikes. I was wondering if anyone had a suggestion for a suitable hubmotor. Since it will be running quite slow I would think that a geared one was best suited? Where can I find a geared hubmotor with a 12.5 inch rim?

She already have an electric car She also has a 50cc mini ATV.


I could simply buy a of the shelf electric bike made for 2 year olds, like a mecatechno http://mecatecno.es/generalt08.html
or an Oset bike http://osetbikes.com/us/oset-bikes-en-US/oset-12-5-racing-en-US/

It would just be cooler to make it myself. And maybe save a few $$ to. My family have a tradition to build thing ourself an also to early introduction to motorized vehicles.
Here is my first car. Custom made by my uncle. It had an gasoline engine.

 

[RideTheLine]

What about a friction drive with a push button on-off momentary throttle? Add an inline potentiometer to your button and you can lock the throttle output.

...for a kids bike, you could probably make the whole thing out of an old powertool...including swappable battery.

That's what I was thinking.

Strap a helmet on and give em a push... You have to learn to fall, in order to run safely...

 

[Samd]

Actually a few of us do it. Most kids can ride a wooden Danish style straddle bike by 2.

One idea a few of us use is to wire a headphone socket under the rear seat in series with the keyswitch. Then use a headphone plug on a string to complete the circuit whilst walking behind.
Kid going too fast? Yank the string.

Just bought my 7 year old daughter a crmo dirtjumper to make up a MX style bike so she cna come riding in the aussie bush. I'll keep upping the current limit as she gets better.

 

[BahamasBiker]

From the OSET owners' forum, it appears that the OSET is a brushed motor.
http://www.trialscentral.com/forums/topic/56640-lithium-ion-battery-problem-on-oset-20-2014/


FYI, brushed motors will almost always have an internal meltdown if driven over their high-RPM limit, even if no power is applied. (Some EV brushed motors, like the Advanced DC 9", will have a warning beeper when RPM limit is being reached).

Once this meltdown happens, the motor will have symptoms and start to get hot under normal running -- in other words, a replacement is needed.

Imo, never buy an ebike that is not brushless, gearless, and has sprockets or chains.

Millions of Asian ebike owners have learned that hub motors are the most reliable.

 

[Simonvtr]

I would install a Out-runner motor inside the rim. Like those long board/skateboard hub motor wheels.

Or do a brush motor setup if you are worried about the rpm of a Out-runner

I have 2 of these in my daughter jeep barbie power-wheels
They are dewalt 18volt motor from power drill
You can even keep the gear attached so you can reduce the rpm.

Or maybe one of these

And use this to mount it

Run some stepper motor belt setup

Have it all control by one of these Chinese controller

Rewire that to a momentary push button at the handlebar.
keep the Pot attached so you can set the speed of the motor.

Maybe something like this?

Simon