# Lithium powered dirt bikes built locally $6k



## ngrimm (Oct 19, 2007)

Just noticed there is a company called Electric Moto about 10 miles from me in Southern Oregone that builds electric off road motorcycles. Looks like a decent operation, more like an actual factory. Even have a few videos. I need to see if they will give me a tour.


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## akumabito (Jun 23, 2008)

http://www.electricmoto.com/ <-- these guys? Their Blade XT looks slick!

1920Wh battery pack.. hmm.. 18Hp would be about 13,000Wh. What sort of range is it getting?


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## electro37 (May 18, 2008)

*Try "Thunderstruck Motors" in Cali.*

They have more experience and better design skills than almost anyone in N. America. They will even custom built your heat's desire. their prices are decent too!!!


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## Little Rhody (Jun 17, 2008)

*Re: Try "Thunderstruck Motors" in Cali.*

They have been around a few years. Build a nice product, and have spent a lot of money on RD. 

They were around just before I built my first bike. (see my avatar) I discovered them mid build. I thought I had something new to bring to market, until I saw there site. 

LR


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## Camaro (Jul 29, 2008)

The only thing I don't like about the blade is that they sell it as a off-road dirt bike, but it's built on a mountain bike frame.


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## Qer (May 7, 2008)

akumabito said:


> 1920Wh battery pack.. hmm.. 18Hp would be about 13,000Wh. What sort of range is it getting?


Not very long if you give it full throttle the whole time. On the other hand, if you keep giving it full throttle constantly I bet either the motor's range or your personal range will be shorter than the batteries. Something's likely to give up before the batteries, either you rev the motor to pieces or you lose control over the bike, possibly in a fatal way. Your pick. 

Full acceleration gives a LOT more horse powers than a vehicle need to keep moving. Those extra horse powers are what's needed to accelerate, thus if you're just cruising that bike won't use all those 13 kW. That's why stop and go-driving always has a bad impact on the range.


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## akumabito (Jun 23, 2008)

Well, yeah... 

I was just wondering what range it would get under normal driving conditions.. they don't mention it anywhere on their website


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## zig06 (Aug 3, 2008)

Let's see... they say it's capable of running with a "larger" 250cc dirt bike.

Stock the eMoto has 18.5 hp, my '02 Suzuki RM250 has 45hp.

The eMoto has a top speed of 45mph, my RM250 can go 70mph with stock gearing.

The eMoto has a curb weight of 199lbs, my RM250 (with gas) is about 230lbs.

Price wise they are both about the same $6k.

But if they really think that they can even stay close to my dust, or any other 250, I really think that they are in some serious state of denile. And if they are willing to gloss that far over on the details, I have to wonder what else they may be glossing over.

Granted, I do like the concept and would like to ride one. But I know full well that performance wise, it's not even close to a 250 or even a modern 125.

Sorry guys.


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## ngrimm (Oct 19, 2007)

Sound like you have a nice 250. Yeah that might be a stretch since I don't know what kind of testing they have done to compare it to a 250 ice bike. It's hard to compare ice hp to electric due to the difference in torque curves though. For instance if you used only one gear on your ice I would guess the performance wouldn't be as good as it is now. I imagine trying to keep the price down is what limits performance due to the cost of lithium batteries but they are getting closer. What's important to me is that it doesn't annoy others with the noise, pollute or run on a dwindling resource.


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## Jeremy (Jul 12, 2008)

The point about average power versus maximum power is well made. You can work out the average power for an ICE powered vehicle pretty easily - just look at the fuel consumption. A good four stroke engine will burn around 300g/kWh of petrol (about 0.5lbs/hp hr of gasoline to those over the pond) on average. Gasoline has a density (in US friendly units) of about 6lbs/US gallon.

If you have a vehicle that does, say, 50 mp(US)g at a steady speed of 50 mph, then it will be using 1 US gallon per hour, or 6lbs of gasoline per hour. If you divide the fuel used by the specific fuel consumption (6 / 0.5) then you get the average power used. In this case the vehicle will be delivering an average power of about 12 hp. Of course, it may well have an engine that's rated at 80hp, but that doesn't change the fact that it only needs 12hp on average.

It's pretty typical to get average to maximum power ratios for ICE powered vehicles of around 0.15 to 0.1 or thereabouts. For an EV, with it's very high torque at low rpm these ratios come right down to about 0.3 to 0.5 or so. This is purely to do with the fact that an ICE engine is extremely poor at delivering torque at low speeds to accelerate the vehicle. An ICE delivers zero torque at zero rpm, whereas a series wound or permanent magnet electric motor will deliver maximum torque at zero rpm. 

If you look at the power figures for a light dirt bike, then you may well find that the average power needed is likely to be around 4 to 6hp.

Jeremy


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## zig06 (Aug 3, 2008)

Jeremy said:


> The point about average power versus maximum power is well made. You can work out the average power for an ICE powered vehicle pretty easily - just look at the fuel consumption. A good four stroke engine will burn around 300g/kWh of petrol (about 0.5lbs/hp hr of gasoline to those over the pond) on average. Gasoline has a density (in US friendly units) of about 6lbs/US gallon.
> 
> If you have a vehicle that does, say, 50 mp(US)g at a steady speed of 50 mph, then it will be using 1 US gallon per hour, or 6lbs of gasoline per hour. If you divide the fuel used by the specific fuel consumption (6 / 0.5) then you get the average power used. In this case the vehicle will be delivering an average power of about 12 hp. Of course, it may well have an engine that's rated at 80hp, but that doesn't change the fact that it only needs 12hp on average.
> 
> ...


Jeremy,
You've made some good points, but be careful when generalizing fuel useage, as they say "your actual milage will vary". Also, one thing that wasn't covered is that dirt bikes are all about acceleration, with wide open throttle conditions happening constantly. Even in cases where a rider is just out playing around, an occasional full throttle burst will be required due to the adverse conditions normally seen in off-road riding. And that's a big part of the alure to off-road riding. So no one rides around at a steady part throttle state, it can't be done.

Getting back on subject, I do like the idea of an electric dirt bike. So much so that I do see myself building or buying one in the future. Beyond the "green" aspect of it, I think that it would just be a fun bike to own. 

But I do have a very large issue with a company making a claim that's so outrageous that it's just beyond explanation. More directly, ElectricMoto's claim that their bike has a performance envelope even close to a modern 250 off-road bike, is like GM claiming that the Chevy Suburban 50mpg!

And we all know that that's not true.


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## TX_Dj (Jul 25, 2008)

I agree with many of the statements in this thread, and disagree with few.

My KTM 525EXC is 254 lbs dry weight, produces around 60 hp peak, and will outrun an obese liter bike to about 30 mph on dry pavement, and will clobber anything in its class on acceleration and top speed.

It gets between 45-60 mpg depending on how I ride it. However, WHERE I ride it, I'm lucky if I can find a fuel stop in one tank of gas (about 90-110 miles), and there are few other places I like to ride. Most of that riding is done at speeds between 5 mph (technical sections requiring thought, endurance, and a ton of clutch modulation) and 80 mph (flat straight stretches), with an average speed in excess of 45 mph.

If I were to ride the e-moto described in this thread, I would A) not keep up with the others in the pack I ride with, and B) run out of juice before I could find an electrical pole, let alone an outlet. (800,000 acres wilderness- you're lucky if the few stops there even have a phone)

If I were to take it to the local MX track, it'd be a blast... but for back woods riding and true enduro situations, it would not be well suited.

But- if they'd make the supermoto version and make it street legal, I'd have fun sharing some percentage of my weekly commutes with that bike and my EV once completed.


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## Jeremy (Jul 12, 2008)

I agree about acceleration being where it's at, which is where the torque of an electric motor is a real asset. Even the torqueist ICE is no match for an electric motor for low down grunt, even if that electric motor has a far lower maximum power output.

Where the electric motor loses out is range and speed. Speed requires power to overcome aerodynamic drag. A bike that only needs about 3hp to do 30mph on straight and level tarmac, will need around 27hp to do 60mph (doubling the speed cubes the power requirement). That's a lot to ask from any electric bike.

Reducing the rolling resistance and drag can bring that power requirement down a great deal, but then it wouldn't be a dirt bike................

Jeremy


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## TX_Dj (Jul 25, 2008)

I won't disagree that electrics make far more torque from stall than an ICE even at 1000 rpm... but isn't acceleration a function of work over time? (I.E. HP?)

I.E. if I have a motor that provides 40 ft lbs of torque at 100 rpm, that's only 3/4 HP, whereas 40 ft lbs of torque at 8000 rpm is 60 hp.

If the ICE bike were lugged out of the chute at low RPM, there's no doubt in my mind that the EV bike would take the hole shot... but ICE bikes slip the clutch like mad so they can make use of the HP peak instead of the torque peak, and it give more of a "slingshot" launch. One of my riding coaches taught me when I was young- if you're using the throttle by itself, you aren't using your potential. The clutch and throttle are used together to get the right amount of pull, the right amount of acceleration, in every gear, all the time. (This applies to dirt bike racing... I wouldn't try this with a dry plate clutch.  )

If low-rpm torque alone were the factor, an unladen semi tractor would be the fastest thing on the road, and it's not. We all know that the torque of an electric is insane at low RPMs, but this dies off rather steeply as the RPMs come up, and the HP curve stays relatively constant throughout the RPM band, as indicated by the Crazyhorse Pinto dyno chart that was recently posted.

Not saying that it's impossible for an E bike to give an ICE bike a run for its money, but they would have to be closely matched in class for it to be anywhere near a fair fight. I'd bet a dollar that in a dirt drag my 525 will out accelerate, out ET and out trap-speed the EV bike we've been talking about, but that's not a fair fight- they're not in the same class, considering they compare it to a 125 or 250. My 525 is the first bike I've ever owned that will kick a roost, stand on one wheel, and still accelerate faster than your bowels would prefer all at the same time.


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## Jeremy (Jul 12, 2008)

Sure, power is a factor in acceleration, but it's the rate at which power can be delivered that's better at the bottom end for EVs, thanks to the stump-pulling torque of electric motors.

Once you get up to modest speeds, the greater power available from an ICE will start to show.

As we're talking about a dirt bike here, I wouldn't mind betting that an electric one would feel pretty much like an ICE one with twice the power for the initial acceleration part. Beyond 25 to 30mph then I've no doubt that the ICE bike would have the definite edge.

For me, acceleration from low speeds gives the biggest grin factor, so I'd be happy with the electric version I suspect.

Jeremy


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## TX_Dj (Jul 25, 2008)

I guess more than anything, I'm just upset that it's not capable of replacing what I need from my KTM at a comparable price.  I'm sure it's a hoot to ride.


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## JohninCR (May 6, 2008)

The ONLY reason your high powered ICE bikes don't already have electric motors is that battery technology has not advanced enough to come even close to rivaling gasoline as compact form of energy storage. If it ever gets close, ICE's will have no place in any application. Electric motors are more compact, more powerful and more durable, so be careful about being too dismissive of electric bikes. Their performance is really only limited by how much they compromised performance for range in the design.

John


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## TX_Dj (Jul 25, 2008)

Not being dismissive. I wanted to build an electric bike when I was 3 years old, and have always been interested in electrics, and started seriously researching the subject 12 years ago and began my first EV conversion 10 years ago.

There's no doubt in my mind that an electric vehicle, adequately engineered and with the right battery technology, will out-run an ICE... but to date nobody has made a production EV dirt bike comparable to my ICE bike. When they do, I'll trade mine in... but I don't care to build my own EV bike at this time... mostly because I'm busy working on my S10 conversion, but partly because I feel I would need to fabricate my bike's frame from the ground up as a purpose-built EV. I typically don't like the looks and feel of converted bikes, as they tend to look ugly and poorly balanced. Looks are important to set a perception with the public, and proper balance is important for confidence-inspiring handling.

I'd love to meet one of those bikes at the track though, so I could go head to head and see just how well it does stack up against my KTM.


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## Matt Bishop (Aug 25, 2008)

Gidday all,
I'm just starting to build an electric dirtbike now, got my batteries, motor, controller and I'm just working through putting the electrics together. Once they seem to work, I'm gonna buy a donor bike and make the conversion. I'll probably start another thread detailing the conversion once I've got something to show.

Anyway, in the planning phase I wondered alot about the things you've been discussing below. I did quite a few calcs and came up with the following graphs:










This is the torque/rpm curves for a 7kW BLDC electric motor and a CRF250X. As you can see, the electric motor has oodles more torque at low RPM. However, the 250 ICE has a much flatter torque curve. So, to get suitable RPM out of the electric, the torque needs to be spread across the operating range (few gears) and the ICE needs to be geared up to provide any torque at all at low RPM (lots of gears).










This is the effect of gearing, the torque of the E/M is spread out to 90 km/hr, and the ICE torque is concentrated down low. The torque figure in the second graph is at the wheels and the first graph was at the engine output, in case you wondered. The red-yellow lines are the CRF, and the Green is the electric dirtbike. I decided to go for only one gear on the electric, as it seems that extra gears don't add much to the top end, and offer higher torque over too smaller RPM to be useful at the bottom.

So, from the second graph I'm aiming for a bike that has maybe half the power of a CRF250X at low speeds, and rapidly less power than the CRF after about 60 km/hr. I'm fairly happy with this, I reckon the elec bike should still be able to roost and pop a wheelie, but will have to wait a couple of months yet to find out.


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