"Misdemeanor" Electric BMX

When you have a family, inevitably, riding an ebike on family outings becomes a bit of a sore subject. For Mom and Dad, there are lots of options for ebikes, but for kids… not so much.

That's why we built electric BMX bikes for our two youngest kids.

Are they legal?

It depends.

While most state laws prohibit anyone younger than 16 years old from riding an electric bicycle, we note that Razor makes a variety of electric powered vehicles for kid use, including a few models of electric dirt bikes capable of speeds of 14 MPH and higher. Our recommendation is that if you do decide to build an electric bicycle for your kid, you want to make it very low powered and only allow them to ride it on safe trails and closed courses. We DO NOT recommend allowing your underage kids to ride an electric powered bicycle on the street where cars are present. And of course they should ALWAYS wear a good helmet.

So how did we build it?

The main challenge with a BMX frame is that the drop-out is narrower than a standard adult bicycle. BMX bikes are typically 110mm between the rear drop-outs, while adult bikes have a 135mm width of which most hubs are designed to fit.

However, a front direct drive hub motor will typically fit a 100mm drop-out since this width is common to full size mountain bikes' front forks. Therefore it is relatively easy to install a front direct drive hub motor into the rear drop-out of a BMX frame. However, front motors do not usually have the ability to install a freewheel sprocket.

For these BMX builds, we special ordered a front hub motor, and - request a rear motor side cover which allows us to mount a freewheel sprocket on the motor. For this build we opted to install a 16T single speed freewheel sprocket, and the bike pedals normally even without the motor powered.

For the rest of the components we used the standard Xie Chang 6FET 25A programmable controller, with throttle and small Lithium Polymer battery which has a nominal voltage of 29.6V (8S) and 5 Amp-hours of capacity. Even with this very small LiPo battery the bike still has a range of 13 miles at 14 mph. Specialized custom-ordered small 18650-based battery packs are possible and suitable in this application if you are not comfortable using LiPo. Batteries as small as 36V/6Ah can be made with as few as 20 cells (Samsung 30Q 18650 cells) and managed by a 25A BMS.

For Dad's that are adrenaline junkies, it's easy to install a better controller and a higher voltage battery to get speeds of over 30 mph with this same set-up.

If this project interests you, contact us and we will special order the motor. This is typically a non-stock item, very uncommon to source state-side by ANY ebike reseller, including the Kinaye website. However, it's a very fun project that you may wish to build with your kids and inspire them to be part of the electric bike revolution!

"Hello Kitty"

In all fairness, we feel obligated to give credit where credit is due when we were kindly allowed to shoot images in front of RayLee's Hello Kitty Jr.-class Dragster. First though, let's get introduced to Jr. Drag Racing -> See Quote

Watching these young dragsters was a hoot! Seeing petite 8-yo little RayLee all suited up for bear, climb into her dragster, and then head down the track in (admittedly) modest quick time… you just have to tip your hat at the courage displayed in that girl and the faith in her parents!

Close inspection of the "Hello Kitty" mechanics reveals an extremely well-constructed vehicle made of top-flight hardware with late-model instrumentation. Given our propensity against ICE, this scale model dragster is respectively one of the finest purpose-build machines for kids we saw that day.

In addition, it takes very little stretch of imagination to replace that loud smelly ICE with a quiet powerful torquey MXUS motor! That's part of the fun of going to the race track and demoing our gear: We are unexpected, yet entirely welcomed in a family-style comradery, regardless of ride (ICE vs EV).

Good on ya!

"The NHRA Summit Racing Jr. Drag Racing League offers kids ages 5-17 a chance to race half-scale dragsters in a controlled environment at many of NHRA's 130 member tracks throughout the United States and in Canada long before they can obtain a state driver's license. Membership in the Jr. Drag Racing League is required for competition.

"The cars that Jr. Drag Racing League competitors race are called Jr. Dragsters and are half-scale versions of Top Fuel dragsters. Using a five-horsepower, single-cylinder engine, a Jr. Dragster can go as fast as 85 mph and as quick as 7.90 seconds in an eighth-mile, though younger age groups are restricted to slower times/speeds."

About the JDRL