8000watt 13" BLDC scooter motor into a 26" full sus KONA

[John in CR]

Just like Zombies found out with his Cromotors, you'll need a modified or custom swingarm. It's not just the width at the axle, but the CG and wheelbase. I typical DS MTB puts you so far back relative to the rear contact patch that you simply won't be able to make use of all that power. Look how far rearward LFP's rear tire is relative to his saddle to be able to handle crazy high power.

You're idea will work with some refinements. I would suggest spending almost half your budget on a controller, because monster controllers are required to really unleash these beasts. Otherwise you might as well go for a lighter lesser motor that are both easier to deal with getting on a bike and are still capable of 8-10kw peaks.

John

[MadRhino]

...It's not just the width at the axle, but the CG and wheelbase. I typical DS MTB puts you so far back relative to the rear contact patch that you simply won't be able to make use of all that power. Look how far rearward LFP's rear tire is relative to his saddle to be able to handle crazy high power...

True that for pure acceleration on pavement, a longer wheelbase that is obtained by extending the swingarm will make the bike much easier to control by placing the weight in the front. Then, one may consider that trial motorcycles are not designed with a longer wheelbase nor place the pegs further forward, despite the extreme torque that they are capable. For some riders, lifting the front is not an inconvenience that limits the use of the full power, but a desirable consequence of the torque required to control the bikes vertical acceleration as well as the more conventional horizontal displacement.

[John in CR]

With a 50lb hubbie I hope he wasn't thinking about trials or other off road type riding. BTW, even with a far longer swingarm and much lower saddle and my big wide load leaning forward my Hubmonster driven SuperV has no problem lifting the front wheel. Actually, for me that is a bit of a problem...at least until we have a better means of throttle control. In the meantime I need to stay away from ebikes that are almost unicycles with a training wheel for street riding, and leave getting airborne to you experts. That doesn't mean I don't want to help come up with an ebike for you that meets your fun quotient going downhill, and is loads of fun on the way uphill, since at some point in the future downhill racing will actually be a lap instead of just downhill.

[MadRhino]

Yep 50 pounds of hub is way too much for mountain riding. Throttle control is my main problem actually, having the power to lift at will is one thing achieved, but having the precise control of it is a must to pull the best of it. I can't see the possibility to build my trial frame with a hub motor yet, and I will have to gear a noisy brushed motor for my first attempt. On the other hand, my lightweight road racer is a beast now, and almost behave like a trial bike since I got it down to 55 pounds, that is about the weight of the rear wheel that is planned by the OP.

[Beachcruzer]

How about a mid-drive? Fabricating a frame mount for that motor won't be any more involved than building a whole new swing arm. Left-side chain straight to a bolt-on sprocket. Keep the donor-bike pedal drivetrain on the right. No need to mess with complicated reductions, but the chain drive will allow you to fine-tune gearing. Now your 30-lbs motor is in the center of the bike. Yes, you'd have to switch donor bikes, but yours isn't really the best for this build anyway. Switch it for something steel with plenty of space in the triangle. Then you can weld on it, stretch it, bend it. Spend the savings on components (brakes and, um, brakes) because the weight savings of your aluminum frame is insignificant compared to the motor and batteries. And you're going to have too much power to worry about weight anyway.

[Samd]

I don't know if you're trolling, or serious, but either way it is wonderful and I am subscribing....

[sn0wchyld]

How about a mid-drive? Fabricating a frame mount for that motor won't be any more involved than building a whole new swing arm. Left-side chain straight to a bolt-on sprocket. Keep the donor-bike pedal drivetrain on the right. No need to mess with complicated reductions, but the chain drive will allow you to fine-tune gearing. Now your 30-lbs motor is in the center of the bike. Yes, you'd have to switch donor bikes, but yours isn't really the best for this build anyway. Switch it for something steel with plenty of space in the triangle. Then you can weld on it, stretch it, bend it. Spend the savings on components (brakes and, um, brakes) because the weight savings of your aluminum frame is insignificant compared to the motor and batteries. And you're going to have too much power to worry about weight anyway.

thats not a bad idea... I reckon you'd be able to shave a huge amount of weight off that hub if you know its not going to be taking the kinds of loads found inside a wheel... ie drilled covers/ lathed down flanges, even the internals could probably be thinned out a bit since they'll be in a less stressed environment. I recon you could probably shave a kg or two off a hx motor if it wasnt going to be in a wheel (someone on es got 'em down below 6kg if i remember, using CF side covers), so doing the same here could yeild a few kg in savings at least! and then you've got a 8kw behemoth that only weighs 90% of a heavy DH bike, rather than 120%

[LegendLength]

When you're effectively doubling the weight of the bike you will find the existing gear is under a lot of stress. This thing for example:



It's about 8 kW (from memory) and even though it's ICE not electric, they've had to beef up certain parts above normal DH mountain bike level. From http://www.fxbikes.com/bikes/ :

Weight: 125 lbs (52 kg)
Forks: Marzocchi Downhill
Rear Shock: From a mini motocross bike
Tyres: MX front and back
Brakes: 11 inch front disc, 8 inch rear disc

The swingarm is clearly MX style and the rims are all MX (like you're currently doing). I'd look at that bike and others and see where they felt it needed updating for that extra power. Another example is:


http://www.apriliaforum.com/forums/show ... kes-beware

[silverrich1]

Thank you for posting JohninCR your scooter build inspired me, i have followed your builds with great fascination because I completely relate to the practical side of using factory-prepared scooter motors rated for high power, since we're going for high power we might as well use the highest power hub motors in production and whittle down the dropout difference.

and.. no offroad, all on-the-road.
The swing-arm was swapped for a steel swingarm.
One question:

question on battery power
Lipo 10s3p
http://www.hobbyking.com/hobbyking/stor ... ouse_.html
Lipo iCharger 10s:
http://www.hobbyking.com/hobbycity/stor ... arger.html

or

A123 20AH
(from the ES wholesale thread) at 23$/cell

With a 50lb hubbie I hope he wasn't thinking about trials or other off road type riding. BTW, even with a far longer swingarm and much lower saddle and my big wide load leaning forward my Hubmonster driven SuperV has no problem lifting the front wheel. Actually, for me that is a bit of a problem...at least until we have a better means of throttle control. In the meantime I need to stay away from ebikes that are almost unicycles with a training wheel for street riding, and leave getting airborne to you experts. That doesn't mean I don't want to help come up with an ebike for you that meets your fun quotient going downhill, and is loads of fun on the way uphill, since at some point in the future downhill racing will actually be a lap instead of just downhill.

[silverrich1]

I will be lengthening the swingarm using steel fabrication. I've swapped the siwngarm from aluminium to steel. batteries / controller will be moved forward on the bike.
Just a small question on Sensored or Sensorless controller?

This one:
http://kellycontroller.com/khb1230124-1 ... -1126.html
24-120V,300A,Opto BLDC Controller/With Regen
or

this one:
http://kellycontroller.com/ksl0925024v- ... p-675.html
24V-96V,250A,Sensorless BLDC Controller

or a lyen 24 fet 4110?

sensorless is not as efficient in the high power range of controllers...but how inefficient are we talking? vs eliminating the sensor wires

...It's not just the width at the axle, but the CG and wheelbase. I typical DS MTB puts you so far back relative to the rear contact patch that you simply won't be able to make use of all that power. Look how far rearward LFP's rear tire is relative to his saddle to be able to handle crazy high power...

True that for pure acceleration on pavement, a longer wheelbase that is obtained by extending the swingarm will make the bike much easier to control by placing the weight in the front. Then, one may consider that trial motorcycles are not designed with a longer wheelbase nor place the pegs further forward, despite the extreme torque that they are capable. For some riders, lifting the front is not an inconvenience that limits the use of the full power, but a desirable consequence of the torque required to control the bikes vertical acceleration as well as the more conventional horizontal displacement.

[John in CR]

Thanks for the compliments. I'm just a meat and potatoes builder who got lucky and bought scooter hubbies almost 4 years ago. Hopefully coming at it from a non-cyclist view contributes something useful. Fat guys need lots of power, and the effects of 100lbs more load for my bikes is lost on most, or many more would have already made the switch. We'll have some prettier stuff to unveil soon and even do some videos. My son runs a pretty tame controller. Just wait till we change that, since he weighs 90lbs less than I do.

| think you'll want more controller than those you listed, because Kelly rates their current based on phase amps. Also, unless you have really steep hills to contend with I'd choose the higher rpm version of whatever motor you choose. That's because they can handle more current, and while the same motor is capable of the same max torque regardless of winding, it means the higher Kv motor is capable of more power because controller selection limits our max voltage pretty severely.

What allows us to go so much higher power than rated with scooter hubbies is that they're designed for loads of 250-300 or more pounds plus rider and passenger, so when we put them on a 100lb bike the load is so much lower than we can safely increase voltage and current.

Something to consider is the smaller tire than a bike + an extended swingarm means lots of empty space is available between the tire and pivot. Think about batteries there. I've done that on several builds. It increases the unsprung weight, but due to leverage the effect is far less than at the axle. With a 50lb wheel, unsprung weight obviously isn't a concern.

[silverrich1]

.....

[silverrich1]

success! I just came back from the tyre shop, having tried on over 20 different assortments of tyres a pit bike tyre / knobbly combo, would give me the equivalent of a 20" bicycle rim on this. more pics on this later. it's a fat boy tyre. so might not need to install it into a rim after all, it's simplified it now, much safer this way, as all I need to do is customize the dropouts and install a 20" front rim.

drill holes around the perimeter of the "rim" and lace it. May need custom spoke lengths. Should work, in theory. Can't say how well. Good luck!

[sflorlando]

Loving this build!

Cant wait to see this rocket take off.

Ken

[lostrack]

This is an ambitious build. Dare I say, square peg in a round hole?

What are your thoughts on weight?

At 22KG your hub is going to be so heavy, you won't want to lift your bike up. With another 20kg of batteries (minimum you'll need to go any range on a high powered hub) you are going to be stressing your frame. You'll need a new rear shock, new springs in your fork, and if you weigh alot yourself, I'd say goodbye to your bike... It looks like a cross country frame, not a heavy hitter DH frame. It might snap.

I've got frame fractures on bikes before, pay attention to your welds under the head tube. If you're bending the rear triangle hugely then this is tantamount to pre-fracturing it.

I strongly recommend a new frame, or a motor more suited to the application...sorry dude!

Sorry to sound negative, you might get it working... just know you can get 8KW out of much lighter motors. It sounds like a really cheap motor with an expensive shell for the tyres.


Qualification? I have a DH bike that has the lightest equipment on it - astro 3220, 15AH lipo, everything else is average weight. It's still about 35kg. Getting 8KW out of it is childs play

[etard]

Couldn't have said it better man, that frame will be a spindly twig with a cannonball hanging off the back. Get yourself a decent bike to put that on, or go with something similar to Farfle's Genesis build:



Definately don't skimp on the frame if you have a 40 lb motor. I have a very similar motor off a scooter and have sidelined my project, but will get around to it soon.

Seen here:

viewtopic.php?f=3&t=29942&hilit=scooter+hub+motor

[sflorlando]

Id love to see some pics of the motor! I am planning on getting the exact one.

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Thanks for your email for the 2kw 13inch hub motor.

As price indicated,it cost USD245.00

And shipping cost to Orlando FL 189.00 by FEDEX.

So total will be USD433.00
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