# 2 wheel-drive E-bike?



## Duncan (Dec 8, 2008)

Don't worry about "synchronizing the motors" - the ground will do that

Which is what happens in any differential

Electric vehicle controllers are Torque control devices - your throttle demands a certain torque - just like the throttle in an IC car/bike


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## Sport1000 (Jun 6, 2015)

Duncan said:


> Don't worry about "synchronizing the motors" - the ground will do that
> 
> Which is what happens in any differential
> 
> Electric vehicle controllers are Torque control devices - your throttle demands a certain torque - just like the throttle in an IC car/bike



Sorry for the noob question here... :

Would each motor have a separate controller or could they both be run off one controller? 

Thanks!


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## RIPPERTON (Jan 26, 2010)

Sport1000 said:


> Would each motor have a separate controller or could they both be run off one controller?
> 
> Thanks!


Yes you will need 2 controllers mostly because these motors are AC but they can be controlled by 1 throttle and you should be able to make a 2WD bike but you will have to deal with a bit of wheel spin from the front because of the weight shift under accel.
You wont be able to make the front spin at the same rate as the rear.
That's why most successful 2WD bikes are mechanical ie chain and shaft drive.
If you want a fast electric dirt bike just stick with RWD.


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## Sport1000 (Jun 6, 2015)

RIPPERTON said:


> Yes you will need 2 controllers mostly because these motors are AC but they can be controlled by 1 throttle and you should be able to make a 2WD bike but you will have to deal with a bit of wheel spin from the front because of the weight shift under accel.
> You wont be able to make the front spin at the same rate as the rear.
> That's why most successful 2WD bikes are mechanical ie chain and shaft drive.
> If you want a fast electric dirt bike just stick with RWD.



OK, so there's not a way to synchronize the wheels electronically (to lock the wheels together like mechanical locking differentials in a 4WD system).

Maybe front wheel spin could be minimized by biasing weight forward with the batteries and raising the forks a bit in the triple clamps? The motor hubs weigh 50 lbs. by themselves, and I'm guessing the rest of the front wheel would weigh 25 lbs., so say 75 lbs. of unsprung weight at the front wheel.

I'm gonna have to eat my Wheaties and get some extra wide handlebars!


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## ken will (Dec 19, 2009)

Have you thought about putting a 10kw motor in the rear for traction, and a smaller 1kw motor in the front to help mostly for steering and a little bit for propulsion?


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## Sport1000 (Jun 6, 2015)

ken will said:


> Have you thought about putting a 10kw motor in the rear for traction, and a smaller 1kw motor in the front to help mostly for steering and a little bit for propulsion?




I'm open to any suggestions. 

According to Enertrac, I'd probably need to find or fabricate a wider triple clamp set in order to get 7.5" of width to fit their hub motor. Plus would probably have to modify forks to accept a 60mm axle. Then there's mounting the rotor, caliper and holder to line up, I'd assume the brakes would have to be larger to cope with the increased weight at the hub.

So, yes, a smaller hub motor up front may be desirable.

Are there any links to a successful front wheel hub motor? I can see why they are few and far between considering the numerous technical challenges. 

Still a working 2wd ATC would be pretty damned cool to pull off....


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## Woodsmith (Jun 5, 2008)

Have you looked at some of the electric bicycle motors that are available?

I tend to ignore them due to the legal power limitations in the UK but I have seen them at 500W and 1kW, maybe even more.
They won't be designed for the weight of a motorbike but might be a starting point for conversion ideas and components.


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## Sport1000 (Jun 6, 2015)

Woodsmith said:


> Have you looked at some of the electric bicycle motors that are available?
> 
> I tend to ignore them due to the legal power limitations in the UK but I have seen them at 500W and 1kW, maybe even more.
> They won't be designed for the weight of a motorbike but might be a starting point for conversion ideas and components.


Thanks for that info! I'll look into it!


ETA: I'm thinking now that a 2wd bike is over ambitious for noobs like us! Better cut our teeth on a RWD road bike and see where that leads us!


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## Dcoxryton (Dec 29, 2010)

Hey Sport 1000, I've built a RWD KTM dirt bike. It alone is an ambitious project. But it is so much fun. I rode a friends dual hub motor bicycle, 2 1000w motors, and it was squirrelly to drive. When you accelerated hard the front wheel would lift weight load and the front tire would spin on you making it hard to steer and control!
Building any dirt bike frame is not that difficult, look at mine on EV Album 3817. Donalds KTM on EV Album. I have built 3 or 4, if you count all the various re model builds of mine, another KTM I built and now the Yamaha with a gearbox, I am building now.
Go to EV West and watch their monthly 1 hour video, the one that starts with thee electric Fiat Jolly. Trent has an electric dirt bike in there similar to mine but with direct drive, as opposed to mine with a jack shaft.
My KTM has a Motoenergy ME1004 motor, a Kelly 72V 500A regen controller, and 48V 40AH of Lithium battery .
weights 240lbs and can go 50mph or 15 miles on a charge on the street


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