When we wrote about this idea the first time there was some debate about whether or not you needed to shift an electric motor. Does it give you a real advantage or is it technology to make it easier for us old timers to make the “shift” from internal combustion to electric? I can’t answer the first part of that question, but it does seem, at first glance, we might feel more at home when our left foot has something to do.
Brammo must feel there’s a good reason for it because they’re going ahead with the technology and judging from the video below, it looks like it works.
Link: TechCrunch
Previously on The Kneeslider: IET Integrated Electric Transmission
Link: Brammo
JR says
I’ve ridden a Zero and enjoyed it, but it’s hard to say whether or not I’d miss the shifting. I think I would…
I think it’s great to give people the option though. Just like you can buy a manual or automatic car; give us the option in bikes too. That’s the key… choice.
Bravo Brammo.
Fred M. says
This is all very interesting, but I want to see actual performance information. Does this give 30% greater highway range? Does it significantly improve acceleration? Does it raise the top speed by a 20mph? Even beyond that, does it make it a lot more practical for everyday commutes that include a mix of highway and local roads?
At this point in their development, electric motorcycles are a cool new tech that offers the greatest appeal for consumers intent on ecnomical, low-carbon-footprint commuting. I would love to get one, but I have a 70 mile commute and really need to be able to hit 70mph occasionally in order to keep up with the flow of traffic. The current generation of bikes is not quite there yet, but I keep reading up on the new developments hoping that there will be an affordable, mass market electric bike that meets my needs.
R6Power says
It should raise the top speed for sure. Range and acceleration will be more or less the same IMO…
I think they should separate these electric bikes into recognizable categories ASAP. This one looks like being equivalent to a four stroke 250.
Fred M. says
There are only two viable electric bike categories: Off-road play bikes and commuter bikes. Making electric bikes look like sport bikes, supermoto bikes, and competition off-road bikes just invites comparisons in which their gas-engined counterparts will win due to their superior performance.
Bob says
As Supermotos make great commuter bikes I can see a market for this style. What’s wrong with wanting a bike with fast handling, good suspension, good torque and with road rubber to tackle traffic and back lanes. When the prices come down I will be very interested in an electric supermoto.
Fred M. says
“What’s wrong with wanting a bike with fast handling, good suspension, good torque and with road rubber to tackle traffic and back lanes.”
Nothing. Which is why the lighter, more powerful, longer-range gasoline bikes are so much more appealing than their electric look-alikes to most buyers. Again, that’s the problem with making electric motorcycles look like performance bikes when they don’t have the performance to back up the looks.
Oscar says
It seems as though a CVT would be more useful. It could keep the motor in its sweet spot for either power, torque or efficiency – whichever the rider wanted at the time.
But that would probably be too heavy and expensive for the application.
Warren says
I was thinking this, too. If the electric motor really does have a narrow band, then it would make sense to keep in in that range and continuously change the gear ratio.
Ola says
I think a conventional gearbox makes more sense for an electric motor. A CVT is more optimally suited for an engine that delivers peak torque in a very narrow rpm range (i.e. a typical ICE), since it more or less let’s the engine stay in the optimum range, whereas such an engine with a conventional multi speed gearbox would be less efficient at either end of the rpm range per gear. However, an electric motor delivers peak torque throughout almost the entire rpm range, and therefore can utilize a conventional gearbox better.
In fact, I have found a little curious that no electric motorcycles has had an actual gearbox until now. After all, a gearbox is not only for utilising the limited torque range of an ICE, but also because it takes less effort to push a taller gearing while at speed, than from standstill, hence improving acceleration with multiple gears up until the taller gearing.
B50 Jim says
It makes sense — even electric motors have their most efficient speed range. Plus it will make it easier for us old-timers to adapt to electrics. Still, I like the idea of twist-and-go; if this is merely to make the bike more appealing and doesn’t improve performance, it’s just unnecessary complexity and extra cost.
Fred M. says
B50 Jim wrote: “Still, I like the idea of twist-and-go; if this is merely to make the bike more appealing and doesn’t improve performance, it’s just unnecessary complexity and extra cost.”
I totally agree with B50 Jim on that. If it’s just adding weight, complexity, and cost without improving range or acceleration, then it’s as useful and desirable as a kickstand on a sidecar rig.
Tin Man says
I dont see why this is so hard to understand, A transmission will benefit an Electric bike by bringing more useable torque when you need it. Allowing a smaller power plant to deliver the performance of a bigger motor. Much like a 327 Chevy only really needed a 2 speed powerglide, but a 4 speed made it better able to utilize the available power.
Fred M. says
The Locked Rotor Torque or Starting Torque of an electric motor is the torque the electrical motor develop when its starts at rest or zero speed. Unlike a gasoline engine, an electric motor can produce full torque starting at 0 RPM. That is why it is possible to have a directly coupled electric motor that has no transmission or clutch.
Also, unlike a gasoline motor, the torque curve of an electric motor is such that there isn’t some “power band” that resembles what one sees in a gasoline engine.
leston says
The transmission existed in the first place to give the engine further limits. Ever ran your motorcycle in 1st gear down the interstate at 70 MPH? Didnt think so. The transmission increases the potential of the final drive sprocket off the engine.
If i take my electric motor and link it with my 4 speed sportster transmission, i will have, undoubtedly, increased the output that the electric motor can put out at half throttle. Now yes i can twist the throttle and probably reach those same performance levels, but i will have consumed more electricity from the batteries.
Fred M. says
You’re making analogies between gasoline engine motorcycles and ones with electric motors? Seriously? How many gasoline motorcycle engines make 250lb/ft of torque at zero RPM? The electric motor in the MotoCzysz E1PC 2010 does. How many gasoline motorcycles make 115lb/ft of torque at 0 RPM and are capable of running from 0 to 160mph in one gear? The electric Mission R does that. Even Brammo’s own high-end sport bike, the Empulse, uses a single-ratio “transmissions.”
Go visit the sites of the most successful and advanced electric motorcycle manufacturers and then come back and explain why they have chosen to run single-ratio.
And let’s not forget about electric cars, like the Tesla Roadster, which costs over $100K, employs a single ratio drive, goes from 0-60mph in less than four seconds, and has a 125mph top speed.
The Chevy Volt has a single ratio drive system. So does the Nissan Leaf, Smart ED, and BMW ActiveE.
If a multi-ratio transmission would have improved performance or range, why did all of those firms elect to go with single ratio drive systems?
It’s not cost, as these firms have spent a fortune creating these vehicles. It’s not because the engineers they employ are stupider than you and Tin Man, either. So how about some actual engineering calculations, or at least examples of multi-speed transmission electric cars that outperform their single-ratio competition? This “seems obvious to me” thing isn’t engineering and what “seems obvious” to you might turn out to be untrue.
rohorn says
It takes X number of watts to achieve acceleration at any given rate or maintain any given speed – changing the RPM isn’t going to change that number of watts significantly. That means how much electricity has been drawn from the batteries won’t change significantly, either. In fact, a transmission may make it WORSE, since I’ve yet to see a lossless transmission that weighs nothing.
A better analogy is: Have you ever run your Sportster from a stop with the transmission engaged in 4th and with the engine off? An electric motor can do that – not even mighty Sportster “torque” can pull that off.
Ever look at the speed/efficiency graphs for electric motors?
None of this post requires an engineer to figure it out.
Fred M. says
My longer comment is awaiting moderation, probably due to the number of links I provided or the length. In the meantime, perhaps you can explain why the engineers of all of the following electric vehicles chose single ratio drive systems:
Cars:
Tesla Roadster (0-60mph in 3.x seconds, 125mph top speed, $100K)
BMW ActiveE
Nissan Leaf
Chevrolet Volt
Smart ED
Bikes:
Moto Czysz E1PC
Mission Motors Mission R
Brammo Empulse
KillaCycle (electric drag racing, 7.824 s @ 168 mph 1/4 mile)
Whether it’s a racing machine looking for any advantage or a commuter vehicle that aims to have the best range, each has a single ratio transmission. It’s not like Chevrolet, Mercedes (smart), Nissan, or BMW just couldn’t justify the engineering or production costs for a multi-gear transmission.
Paul Crowe - "The Kneeslider" says
I’ll leave it to the “engineers” to make their point about why a transmission does or doesn’t help, I can’t say one way or the other.
But, Fred, it’s odd that you point out how all of those manufacturers only use single speed drives when the subject of this post is Brammo, one company you point to, getting ready to introduce several bikes WITH a 6 speed transmission.
Maybe they just didn’t have a good solution before now and this one by SMRE works so well they decided to go ahead and use it. Since Brammo has the global rights, that might explain why none of the other electric motorcycle companies have adopted it.
rohorn says
I’m going to take the risk of saying that I think this will do to Brammo what the VDue did to Bimota.
This reeks of reactionary marketing department design from concept to production. If the comments around the web are much to go by, they were listening intently to people who aren’t going to buy one anyway. Most failed consumer electronics become an inconspicuous detail in a landfill somewhere – I wonder how the principle interests will handle these.
Fred M. says
Paul, as a “writer,” perhaps you could have worded my comment better, but I didn’t say that Brammo only uses single ratio drive systems. I did note that Brammo’s top performance model uses a single ratio drive train.
Aprilia makes some of the best performing sport bikes on the market. They also make the automatic transmission Mana GT. Just as the Mana GT appeals to a certain market segment, so do the manual transmission Brammo models .
Perhaps an engineer from MotoCzysz, Mission Motors, or Zero Motorcycles could comment on why they elected to go with a direct drive system for their motorcycles.
leston says
Im gonna lean with the engineer’s on this one, the folks at brammo, SMRE, and the knowledge i obtained with my engineering degree, and go with the idea that these folks wouldn’t invest time and money in something if they didn’t see a reason too.
So since the killa, brammo, and mission don’t use transmissions, neither should anyone else. Because current electric motorcycle transportation is tried and true and there are no more further advancements to be made. (please hear my saracasm)
Fred M. says
Leston, there are a lot of marketing people who are having orgasms reading your posts. They love people who unquestionably believe; Faith-based consumerism. Don’t confuse yourself with facts like 746 watts being equal to one horsepower. Don’t demand independent test results to show that something works. Just get out there and buy up magnets to put on fuel lines, bottles of Slick 50 oil additive, Splitfire spark plugs, and tablets you put in your fuel tank that will double your gas mileage.
Engineering is hard with all of that math, all of those graphs, and the tests. It’s much more fun to believe that some company with a net worth about equal to the copier paper budget at Nissan has figured out how to make a magic transmission that has eluded the engineers at Tesla, Nissan, Daimler, and BMW.
todd says
Tin Man is right. Having more gear reduction will give you stronger acceleration. Having less gear reduction gives you a higher top speed. Before this you chose one or the other. Now, having a multi-ratio transmission, you can have both.
Reducing the final gearing on this bike should make its power off the line more comparable with a typical motorcycle without sacrificing the top speed. Basically it creates more torque at the rear wheel.
You can just keep it in second if you don’t want to shift – or you can keep it in first for hard acceleration and off-road work.
-todd
Brent Meeker says
Look up the power vs rpm curve for an electric motor – they’re plenty available on line. You’ll see that an electric motor has a power curve very similar to a ICE, just broader. Looking at a commonly used 18hp motor I see it reaches max power at 2000rpm. At half that, 1000rpm, it makes 13.5hp. So if you geared it for top speed, about 85mph, then at 42.5mp you’d have 13.5hp on tap. If you could downshift a gear, you could have 18hp on tap. So transmissions can improve the performance and efficiency of electric bikes – whether they do enough to compensate for the weight and cost depends on other factors.
Fred M. says
Torque curve for an electric motor:
http://zeept.files.wordpress.com/2006/06/pmg_080_torque.JPG
I just don’t see where that’s very similar to an internal combustion engine.
Brent Meeker says
I said POWER vs rpm….not torque. If you calculated the power vs rpm from the torque vs rpm curve you cited, you would find it looks like this one
http://www.recumbents.com/mars/pages/proj/sadler/assist/projsadassist.html
Sure it’s not exactly like an ICE, it’s much broader and it doesn’t drop off sharply at the top end. But it has the same characteristic that makes transmissions useful for other engines: it has a power peak. Note that everybody uses a single-speed transmission in their electric vehicle. Why? In order to put the peak power at the point where motor power equals drag power – in other words in order to maximize the vehicles top speed. This however means there is less than maximum power available at lower speed – unless you have a transmission to select a lower gear. That said, electric motors have relatively flat power curves so multi-speed transmissions may not be worth the cost/weight. I certainly don’t see why Brammo would select a 6-speed transmission.
todd says
Tesla did have a multi-ratio transmission at one point. It improved acceleration. From what I recall, they didn’t feel that the extra drag and power loss that a strong enough transmission created wasn’t worth the extra acceleration.
I don’t care how much torque a motor puts out, only how much torque is translated to the rear wheel. I always like to point out that you can easily crank out well over 100 ft-lb of torque on a bicycle and you won’t accelerate nearly as hard as a GSXR1000 with “only” 80 ft-lbs. The GSXR drive train reduction multiplies the motor’s torque 11 times so there is nearly 900 ft-lb of torque at the rear wheel. That’s why it accelerates so hard even though there is less torque at the crank than on your bicycle. Your bike, on the other hand, is geared up so you can spin the rear tire faster than you can pedal.
Most ICE’s have a clutch. It is very easy to start from a dead stop since you can dial in however much torque you want as you release the clutch. An engine never starts out at zero RPM.
-todd
Narflar says
Now, this actually makes sense. Electric motors are more efficient at higher RPMs. They may have max torque at Zero RPM but that is not where they are most efficient. With a trans you could keep the motor spinning higher for the speed you are going. There is a reason a bunch of home made electric cars want to keep the trans so they can keep the motor at it’s ideal speed for better range.
On the other side, all of these commercial electric vehicles have had lackluster acceleration to preserve range. With a trans you have an option. Leave it in 6th gear and putt around extending range or run through the gears and have some fun.
Paulinator says
Fred you`re right. DC motors put out massive torque at rotor-lock. The down-side is the massive current draw. When RPM is factored-in, the result is a horsepower bell-curve. Measure hp against current and you`ll find another bell-curve illustrating efficiency – and it has a sweet spot. That is where gearing would benefit an electric drive…by keeping that motor running in the sweet spot.
There are other more practical electric motors that use fusisticated controllers for speed and current management, though. I`d use 3-phase with a frequency drive.
Warren says
That “sweet spot” or “powerband similar to a 2-stroke” (as another article I read described it) sounds ideal for a Continuously-Variable Transmission.
I think a computer that constantly monitors RPM and speed and other factors could do a better job at accelerating or optimizing battery usage than any human could.
OMMAG says
You guys should know that whatever the results are … no one knows until they try …. so put a transmission behind an electric motor and see what happens.
I won’t bore you with my credentials … suffice to say that I am well enough educated in power and control systems to figure out a thing or two. One thing is that the torque output graph provided by Fred M. is the theoretical ideal result.
Put a motor into a system with losses and power supply limitations and it will not look like that linear illustration. This is because all the components of an electrical power system interact so that the actual output of that system is a result of all the interactions.
You have to understand and model the power supply characteristics, the motor power consumption characteristics, the motor torque characteristics, the mechanical load characteristics, the thermal losses and the applied controls characteristics.
As far as I can tell … you could make a transmission work behind an electric motor …. but the price you would pay is loss of efficiency. Batteries would be sucked dry in short order because the motor would be kept in that fat part of the input / response curve. This would also increase thermal losses.
Upside should be that you can keep the motor in the bottom fat part of the torque curve. The benefit of that being that you could get a strong impulse of acceleration on every upshift.
In short you could have a lot of fun banging upshifts and burn out all the wiring on every part of the machine …. go down in a blaze of glory …. unless you choked the system back and then you lose the benefits.
Net result …… you might as well keep the motor in a direct drive mode.
IMO ….
Paulinator says
OMMAG, ummm, ya……?
Mark says
There is a major difference in an electric motor vs. an ICE. Their torque curves are almost the exact opposite. An ICE has very little torque at low RPM, and builds steadily as RPM increases, so it makes sense to use a gearbox to keep the ICE in it’s higher rpm range and use the transmissions torque multiplication at low road speeds.
An electric motor is just the opposite, it produces it’s maximum torque from zero and holds it to a certain RPM depending on voltage applied, at which point BEMF of the motor starts working against it. At that point the torque falls off dramatically. A typical example would see an 8000 RPM motor produce 65 lb/ft from 0-3000 rpm fall off to as little as close to zero at 8000 RPM.
Using a transmission on this example would force the motor into a higher RPM range, where it has less torque. It’s quite conceivable that you’d end up with a net loss of torque in many circumstances.
I do think that there would be some advantage at very low road speeds, providing you don’t hold it in gear too long. One thing for sure, a transmission on an electric motor is far less effective than on an ICE. Whether or not it’s worth the extra weight, space and cost vs. just using a larger motor or raising the voltage through more batteries is something that would have to be calculated and tested. I’m not convinced so far.
Fred M. says
I am not going to comment further on the specific engineering aspects of this. I will say that one would think the automotive engineers at Chevrolet, Nissan, Daimler, Tesla, and BMW would have fitted transmissions to their electric vehicles if there were a performance or range benefit to be gained.
Tin Man says
Mark, Your looking at it backwards, Let a smaller engine run in the high torque range up to say 4K, then upshift to a taller gear to use that torque to increase speed. In effect use the gearbox to increase the speed of the bike with a smaller engine. Not to multiply the torque on takeoff on a large engine, but to better utilize the power of a smaller engine. Time will tell.
Adrian says
Not only will they be offering a foot shifter on their new e-bike, but to further put old-school bikers at ease, Brammo will be pegging a playing card to the front forks to give that authentic \brrm-brrm\ motorbike sound!
Warren says
LOL!
leston says
i spit my coffee on my keyboard
rob says
Dry clutch sounds…
rob says
Backfires and forced induction whine.
Warren says
When I first read about SMRE working on a transmission for electric bikes, I was hoping it was an idea that would go away quietly. I prefer the (perceived, at least) simplicity of a direct-drive system. A transmission will add weight and additional maintenance as well as the potentially high repair costs associated with it.
Here’s something that’s been bugging me, why did Brammo use chain final drive on the Empulse models instead of a belt?
Sick Cylinder says
Probably because it’s cheaper, lighter and exposed belts are a bad idea off road.
Ken says
The Empulse is a street bike…..
Belts are really strong and much lighter than chain! The weight of the whole system (pulleys/belt/tensioner) might be heavier than chain/sprockets though….
Recumbent Rider says
This particular argument, gears on an electric or not, has been ongoing for quite some time now at the best place I’ve found online to talk electric bicycles/scooters/motorcycles, endless-sphere.com. The consensus there seems to be that gears can increase overall efficiency modestly by allowing a somewhat smaller motor to run closer to its most efficient point more of the time.
Designing and producing an efficient and reliable transmission for electrics seems to be a problem, recall that the Tesla at least started with a two speed and dropped it because it was unreliable.
There is a nice Java based e-two-wheeler simulator available on that site, I’ve modeled geared and single gear e-bikes quite a bit with it and it comes remarkably close to the numbers many people report from their machines. By simulating the same setup with different gear ratios you can get a feel for what the performance would be with multiple gears.
Download EbikeCalc.zip at this link.
http://www.endless-sphere.com/forums/viewtopic.php?f=2&t=6892&p=287797#p287797
Paul Crowe - "The Kneeslider" says
In the endless debate between thoughts and theories about transmissions on electric motorcycles, it gets to a point where there’s no reason to debate any longer. In any debate where an actual test can be performed to find the answer, eventually you have to run the test.
Until someone compares the actual performance of an e-bike with a transmission to one without, everyone will keep repeating what they’ve already said. Brammo should be able to help answer the question with real data before long, until then this discussion will keep going in circles.
Fred M. says
Paul, what bothers me is that Brammo made various comments about the feel and exeprience of riding their 6 speed electric bike and a vocal contingent reinterpreted that as Brammo making claims regarding measured performance. I would like to see some test results. I expect that the flywheel effect could let them jump off the line a little faster, but at a cost in in battery life.
B50 Jim says
Adrian —
Playing cards in the spokes sound \tinny\, like, well, playing cards in the spokes. An alternative is to use party balloons; the long type, tied to the fork at each end so they rub in the spokes. Not as durable, but they’re quite loud and sound surprisingly like an English twin. When I was in grade school, only the coolest guys used balloons; they carried spares in their pockets to refit when the inevitable breakage occurred — just like an English twin. The rest of us had to satisfy ourselves with the cards.
Ken says
No one ever told me about the baloons! Dagnabit! Now my childhood was not near as glorious as I once thought it was…. Good thing I’ve got two boys who will be riding bicycles in a few more years! I need to find a picture to see how it was set up!
B50 Jim says
Ken — as near as I can remember, the balloons were simply tied to the fork by each end — don’t inflate the balloon fully, leaving three of four inches of “teat” at the end. That gives you enough to wrap each end of the balloon around the fork and tie a simple knot. Underinflated, they last longer. You’ll be surprised at how loud it is — none of that wimpy “clackety-clack” of baseball cards.
todd says
I’m going out to the garage right now with a handful of balloons…
-todd
rob says
“gears can increase overall efficiency modestly by allowing a somewhat smaller motor to run closer to its most efficient point more of the time”
Thanks Recumbent Rider.
I think that statement covers it.
The question is it worth it? Weight, reliability etc.
Thanks to Brammo, I think we are going to have some test data soon.
I smell the spirit of inventiveness.
Fred M. says
Smells more like the spirit of marketing to me.
Gavin says
I’m no engineer, but I would have thought that any efficiency gains arising from being able to keep an electric motor within it’s optimum operating rpm would be far outweighed by the additional mechanical losses from the transmission itself ? Over the years I’ve regularly read of these losses being in the region of 15%, although this figure relates to cars rather than motorcycles.
asdf says
I would own the bike in a heartbeat if the powers that be ended all internal combustion engines. An electric bike with something to shift seems more fun to ride regardless of what some opinions may be. In other words Shut Up and Ride!
Fred M. says
I value performance. You value shifting. I’ll take a faster, lighter bike with longer range over one that I get to shift. To each his own.
Dan says
what a debate. for anyone interested in some serious engineering data check out http://www.zeroshift.com
they have a seamless shift constant mesh gearbox rumored to be the magic ingredient in the HRC rcv motogp onslaught and some great indications of how it can improve electric engine efficiency.
the real problem with any conventional gear box connected to an electric engine currently is that the starting torque will destroy clutches very quickly and the weight of most cvts outweigh the efficiency benefits.
the real issue of electic engines is top speed and range, there is no doubt that a multistage transmission will improve these factors it’s just finding the right one that has no doubt been the hurdle readily avoided by many of the players in the hybrid/electric market.