Look at any electric motorcycle these days, whether TTXGP competitor or one of the first general purpose commuters and you’ll notice one thing is missing, the shift lever. Electric motors have all of this torque available so you just twist the electric throttle and pour the electrons to the motor. Want to go faster? Spin the motor faster.
SMRE Engineering of Italy, figured this was an inefficient way to do things, but also, the lack of transmission and shifting took some of the enjoyment out of the ride, so they built the IET System, an electric motor with a six speed mechanical transmission and clutch, a mechatronic motorcycle. Software can map the motor’s performance characteristics for whatever you might need or want while allowing a smaller motor and battery pack than necessary without the transmission since multiple gears keeps the motor in the most efficient range. The smaller battery pack makes up for the additional weight of the transmission.
Software mapping can also simulate the deceleration of a standard engine during which the motor acting as a generator can recharge the batteries. Plans are to start with a pit bike and then advance to a Supermotard.
Those more familiar than I am with the design and engineering of electric motorcycles can comment on whether their reasoning is sound, but the fact that they’ve built it and are running the system successfully is a strong argument that it works. Even if it didn’t add to the efficiency, the idea of shifting is so ingrained in many of us, that alone might make the whole thing worthwhile. I think it’s a great idea.
Thanks for the tip, J. !
Link: Motorbox and translated version
Link: SMRE Engineering
Max says
So that I have this straight: They removed weight with a smaller motor, so that they could increase weight with a friction causing (pronounced power robbing) mechanism?
skadamo says
I’d like to see the math but I have a hard time believing the tradeoff is worth it with the current state of battery technology. The theory of keeping the motor in the efficiency sweet spot is sound. Unfortunately it looks like the length of the system keeps the heavy batteries from being mounted lower in the frame.
One small thing to think about, many electric motorcycle companies encourage their riders to coast/glide as often as the can to replace hard braking/acceleration cycles. This allows them to get as much out of the momentum generated by the batts and motor. Depending on the way the system is engineered it might improve gliding efficiency or take away from it. Depends on what is spinning and meshing when the clutch is pulled i guess.
I am glad to see someone experimenting with this.
Trabb says
Makes sense to me. May lead to more efficient motor design. Bearings are designed to be run in a certain rpm range for maximun longevity so the whole machine may become more reliable. Besides that, I like to shift, too.
Derek Larsen says
This does make sense–in certain applications. Having 100% torque instantly is nice, but being about to control it is beneficial as well, obviously on surfaces offering poor grip. Like this mucky wet weather here in Baltimore today, dialing down the torque would keep the rear wheel from slipping and spinning.
However, I believe the same thing can be accomplished with a software controller modulating the power heading into the motor. A transmission may be perceived as being more robust, but it’s still more moving parts to potentially fail. I think their next step should be a trials bike.
Jon Hutchison says
Bunch of interesting ideas here. regenerative braking energy recovery might be inproved if the system could beauto or manually downshifted to increased 1) \braking\ resistance and increase speed of the generator. Few electric motors drive whele directly and a t least a few gneras might make sense for hill climbs, hard acceleration and so forth.
Years ago there was a device called a Ciba Dynastart which was both a starter and generator combo used on small cars like the Isetta and some NSU’s space weight and vastly improved electronics might make a relook at this worthwhile for bikes. For that matter as a generator/starter & accessory motor for hybrids
Mark says
A transmission attached to an electric motor is much less beneficial than to it’s ICE counterpart. Attempting this shows a lack of a full understanding of how electric motors deliver power compared to an ICE.
A transmission is ideally suited to an ICE since they have little power at low rpm’s and power increases with speed, for the most part. So, a transmission enables an ICE to run in it’s higher RPM range were it runs most efficiently and produces the greatest amount of power.
An electric motor is the exact opposite, it transmits it’s maximum torque from essentially zero RPM and falls off quite dramatically as RPM increases after a certain point.
Adding a transmission forces the motor to run at a much higher RPM and out of it’s ideal torque range. The net gain of torque multiplication via the transmission gear ratio is often more than offset by the loss in motor torque due to forcing the motor to run at an RPM that’s past it’s maximum torque range.
For example a motor producing 100 Lb/ft of torque at 0-2250 rpm will produce as little as 5 lb/ft of torque at 7500 RPM.
Effort directed towards operating at higher voltages and increasing the motor’s RPM capabilities reap much higher rewards, as the higher voltage extends the knee in the torque curve of the motor through more of it’s RPM range.
The ideal motor can then be geared for maximum slow speed acceleration, while still being able to rev high enough for good maximum speed, while having the same amount of torque available from zero to it’s maximum RPM.
B50 Jim says
It’s amazing how much thought and experimentation is going into electrics now. At this rate we’ll be able to buy electric bikes, cars and light trucks far sooner than we thought.
This approach sounds good on the surface — all motors, electric or fuel-powered, have their optimum operating speed, and being able to get away with a smaller motor always is a plus. It should more than offset the added friction in the transmission. That being said, it appears that SMRE did this just because they wanted to shift the bike. A big advantage of an electric is simplicity, and adding a clutch, complex gearbox and more controls seems like a step backward. A more efficient way to handle torque would be to add digital control to the motor and let the computer take it from there. Also, a transmission eats a lot of energy when coasting down from speed, so that would reduce the amount of regenerative braking available to help recharge the batteries.
The riders who will buy electrics in the future might not even know what a gearbox is — most cars and light trucks sold now have automatic transmissions. They’ll want to simply twist the speed control (won’t be called a throttle) and go.
WRXr says
Torque with electric motors is not the obstacle, high speed is. Therefore if the tranny is set up to allow higher road speeds from a comparatively small power motor, it absolutely make sense.
JR says
I’d be interested to see test data with this, since electric motor torque drops off with higher rpm. Power output (current x voltage) could still be about the same even spinning lower rpm’s but you would have more torque available at higher speed.
There is inefficiency in a transmission of course (more stuff to spin = less power to the ground).
This could be more of a fun/performance (at least simulated performance) idea than an efficiency idea.
Cool either way. I like shifting.
Todd says
Finally a real trans behind a small torquey electric motor in a bike. I knew someone had to come up with the idea sooner or later. I guess the only other option would be a small CVT trans instead of this and the “one” gear method. Yeah it might be heavier, but this will draw them in like flies if it is found to be reliable and strong. And yes just like everyone else I like to shift too!
todd says
Mark is off a little. Sure, an electric motor makes a lot of torque from zero RPM, but where he gets it wrong is that the motor does not make max POWER there nor does torque fall with the rise of RPM. Peak power occurs (much like in an ICE) at the higher RPMs where torque is still high – before it eventually falls away. If you can spin a motor higher you can get more power while requiring less torque. Motor efficiency occurs over a wide range not a specific RPM, and certainly not near zero RPM.
The benefits are: lighter, less expensive motor and controller, less current draw, and consequently, smaller wires, less heat, and lower shock hazard. We all understand the benefit of having more POWER. Here you just need to crank up the voltage.
Having more gear ratios potentially means you can have more torque available at the rear wheel with a smaller motor than you can have with a larger motor. This is true for any type of motor.
It’s not too tough to get a nice, close ratio, fully lubricated tranny; just hack-saw one off the back of a CR250 motor.
-todd
Mark says
Todd, there is a good reason why so few have tried this before. It’s not nearly as effective as you think for the reasons I stated above.
Additionally, electric motors are somewhat deceiving in that their torque outputs are much higher relative to their HP output. You also have to look at the power or HP output as well.
A 100 lb/ft electric motor will only have approx 1/2 the HP of an ICE with similar torque, and all the transmission gearing in the world is not going to make up for that.
Thure says
Even though electric motors have a favorable torque output and curve. Everybody seems to forget about torque multiplication. And the relationship between horsepower and torque and RPM. Taking off on a regular ICE, say with 50 ft/pounds torque at say 5252 RPM, if you rev this motor to just over 5K RPM and drop the clutch you have a first gear torque multiplication of app 3 to 1 making it feel like a 150 ft/pounds of torque and the motor is putting 50 hp to the ground for a lively takeoff. On your basic no clutch no transmission electric bike, even with a 100 ft/pounds you are still gonna be taking off at 0 RPM (ie. from a standstill). If you do the math, well you end up with 0 hp as well. And you have to wait for the power to build with the roadspeed.
So even though the electric motor has a superior torque curve this makes a lot of sense, putting a trans after the electric motor.
Thure
Thure says
Then you also have to remember the cool whine from the electric motor when you rev the balls off it in neutral….
todd says
It’s very comparable to the typical big-twin vs little four. The big twin has twice the torque but half the power (HP) of a smaller, higher revving four (not inherent to configuration, rather, tuning). Small fours are geared lower for the net benefit of having more torque available at the rear wheel at a given speed than the big twin that needs to be geared up. The little motor is lighter too and requires less frame mass to keep everything in line helping matters more.
Besides, your last comment is misleading. Power is a factor which includes time so if they’re spinning the same RPM they will have the same HP. Power is not dependent on its source, rather its application.
The reason so few have tried it before is simple; cost. How much does a transmission cost to develop? Tesla gave up some acceleration (and subsequently added a larger motor) because it ran out of money developing a tranny that could handle the motor they were using and its relentless immediate twisting forces.
Just look at the development of cordless drills. Crank up the voltage, spin the motor higher with more gear reduction and you can get more driving force out of a smaller, lighter, and more battery-friendly drill.
-todd
todd says
Thure, good point. It’s not quite that simple though, since a free-revving motor is not typically at much throttle at those RPMs. You would still need to wait until you screwed the throttle all the way open once you dropped the clutch to experience the full torque capability at that RPM. But, you’re right; you’re starting out with much more power to the ground launching an ICE than an electric.
-todd
Tinman says
A smaller motor with a trans can put as much power to the ground as a direct drive larger motor,DUH. A big ICE V8 could provide adequete performance with a single speed trans with a loose converter, A trans is used to multiply the available power, no matter the source of the power. A highly effeciant tranny would allow a smaller electric motor to match the performance of a larger electric motor.
Steve says
I have to go with the pro transmission side!. Using the torque multiplication will allow a smaller motor. Besides, in high gear the drive would be 1:1 with no frictional losses.
Plus I would think that if regenerative braking is used, you would get more beneift of downshift braking?
Lastly, the more conventional it is, there are less old habits to relearn. That has to help win over riders to electric.
OMMAG says
“…. Software can map the motor’s performance characteristics for whatever you might need or want while allowing a smaller motor and battery pack than necessary without the transmission since multiple gears keeps the motor in the most efficient range. The smaller battery pack makes up for the additional weight of the transmission….”
Check …. exactly what I’ve been saying about electric vehicles for years now …. you can use a transmission and get a direct benefit.
Erick says
Finally someone is making sense. transmission is good, if not for performance, at least keeps me wake up during long journey. lol
spectator says
More spinning crap, like gears, adds complexity, friction, & weight. Spend money developing a better battery/motor. At best, a two speed transmission might help a cheap motor perform marginally better without washing out the gains with friction and rotational inertia. File this under dumb.
Wave says
Apart from losing the joy of shifting gears and the variation in motor noise, I would have imagined that the most effective transmission to use with an electric motor would be a CVT. You could control both the motor torque and the CVT’s ratio electronically to keep the motor at maximum possible efficiency across the entire speed range. .
Chris Y. says
There is definitely an advantage to having a transmission hooked up to an electric motor. The powerband is quite broad, but at higher RPMs it would consume power while torque falls away- it’s ideal to have a transmission for the sake of keeping the revs LOWER, while allowing a high level of acceleration from being able to multiply the torque output from the motor. It almost reminds me of shifting a diesel engine actually…
Even so, I think 6 gears is overkill. A two or three speed transmission would be better.
However, I honestly think that for the majority of people (where “twist n’ go” is more ideal), a CVT hooked up to an electric motor makes sense, as long as the CVT is beefy enough to handle the torque.
J. Smith says
I suggested this article because quite frankly I think it is a great idea.
Having to live everyday with my electric scooter here in China I know very well what it feels like to drive an electric vehicle. Now of course this is a 100 buck lead-acid pile of junk, but the principle is still the same.
I believe the “twist & go” is an ideal solutions for scooters. People who buy scooters do so because they want cheap, easy transportation, combined with some fun and good through traffic.
However people who buy motorcycles certainly don’t want to just “twist & go”. Frankly I always can’t wait to jump on to my motorcycle back home and start shifting some gears after being stuck in a single gear for months. Since it’s a scooter, its acceptable, but if it were a motorcycle I would never ever buy it, nevermind the range or power.
Speaking from personal experience there are several advantages I would see with this IET. Now keep in my that I’m comparing with a lead-acid 1 kW, 5 year old electric scooter bought for 100 bucks, so it might not be entirely accurate.
Problem number 1 is that at speed, torque really becomes very little. When I’m going about 3/4 throttle and want to overtake I feel like I’m glued to the road. Gears would help this overtaking process, which is especially helpful for highways.
Problem 2 is that especially when going uphill, there is no real way to modulate the speed. This may be because my scooter is pretty weak, but when I’m going up a steep hill, my speed is pretty much limited by the torque, meaning I have to go awfully slow to be in the “high torque” region or else wouldn’t be moving at all. Again gears would solve this problem.
Lastly I think motorcyclist are never gonna make the jump unless there are gears involved. I’m all for single gear electric scooter, that makes perfect sense as they should be as cheap and trouble-free as possible. Yet motorcyclist want more. They don’t want cheap transportation, they want thrills, acceleration, fun. They like to get their hands dirty and mess with the transmission and ratios. That’s why I think this is a great idea and think we’ll see lots more of this in the future.
Einspur says
Electrics with shifters and ICE’s with automatics,( Hondas dual clutch ,Yamahas electric shifter ). A little something for everyone and more things to argue about. It’s good for the sport.
B50 Jim says
Most of the arguments here for gears are for the torque multiplication they provide, allowing for a smaller motor. In the lower gears this is true, but in top gear, which is direct drive, you lose any multiplication. This happens at higher speeds, exactly the time the motor needs more power. The smaller motor that worked so well at lower speeds with gears might not have enough guts to haul the machine at road speeds. Anyone who has driven an old Dodge Dakota pickup with an ancient, 2.5-liter Chrysler 4-banger knows what I’m talking about.
The gearbox approach might work well in a trials bike that spends most of its time crawling over logs and up outcroppings, but in a street or road bike it still would need a substantial motor to keep up with traffic. I like to shift as much as the next guy, but I recognize an electric bike is a substantial change from the “old days”, and if it doesn’t need gears, why go to the extra bother of adding them?
An electric motor is totally controllable by digital means; its torque can be limited at lower speeds and called up when needed, without the complexity, weight and expense of a separate gearbox. We haven’t heard the last of this argument, but when the dust clears, I think the simplicity of a motor with direct final drive to the wheel will prevail.
Gyaerny says
I would rather have the right motor for the job, without the transmission. Electric motors are efficient and require relatively no maintenance. Adding a transmission would require some sort of regular maintenance and increase mechanical power losses.
woolyhead says
Now we’re cooking with gas ! I test most of my inventions and am pleasantly surprised that theory doesn’t always translate directly with real world performance. There is no “best” way to do motorcycles…..look at the variety over the years. Simple = sometimes good sometimes bad…………
todd says
Jim, it takes more power to accelerate a vehicle up to speed than it does to maintain that speed. In other words; if you can get there, you’ll have no problem staying there.
Remember, we’re not talking about gearing a low RPM motor down for more torque, we’re talking about gearing a high RPM motor down for more torque. More RPM means more power (i.e. leverage). It’s always beneficial to have more power.
-todd
Mule says
This is a totally different powerplant than we are used to. Torque all the time. I’d like to see a graph more this motor’s “Efficiency”. How good to how bad? A tranny just so we can “Feel good”? How about a teet too? Or how about we learn the characteristics of a new motor and just run with it?
Also, I’m curious what it feels like when backing out of the throttle into a corner vs. downshifting a tranny attached to a freewheeling motor. Like a slipper clutch as free-wheeling as possible? or wheel-chirping decel? No indications there.
Mule says
Typo. What I was trying say was: It would be interesting to see a graph that shows the power curve, such as it is on this motor, Why and where does it become ineffecient? And as Mark says, if torque falls off at increased RPM’s, that would require the rider with a tranny to short shift all the time instead of reving to keep it on the pipe. Yes, no?
Tinman says
B50Jim, A Dodge Dakota with the old school and proven 2.5 engine would be loved in most every country in the world, except N. America. We are addicted to over powered vehicles to the point of absurdity here in the U.S.. 145 HP bikes and 300HP cars are fun,but hardly practicle.
Thom says
I always liked the 2.5 Dakota…. imagined building one with the Shelby Turbo motor…. But I digress… This is not a matter of “right” and “wrong”- It’s personal preference. It’s also a matter of having the right product at the right time. Historically, motorcyclists have been resistant to change from the norm. In 1914 Indian offered a bike with an electric starter/generator and rear suspension. 1914! ? But people were unable to deal with the change and it set motorcycling back 50 years. And why did the Yamaha GTS1000 fail? In spite of its benefits, the swingarm front suspension was too much for consumers to accept. Maybe adding a transmission to an electric motor isn’t the best way, but it MAY be the way to open the door for later evolutions of the technology, by being a little closer to what we, as motorcyclists, are used to.
Mule says
@Thom, Generally, suspension innovations like the Elf Honda GP bike, Foobar swingarm, RADD, Moto-Cyzyx(?), GT1000 Yamaha, Paralever BMW, that weird thing Mert Lawwill builds, if shown to have a clear advantage are scooped up, ideas stolen, incorporated, patented , mass-produced or seen on future production bikes as quick as the manufacturers can get them to market. Some of these are just gimmicks and set the bikes apart from the masses (BMW). If the BMW front end was “The Answer”, it would be on their new superbikes. It’s not. Marketing perhaps? If the front end was better and the bike kicked ass in all the Comparos, it would be the bomb. It’s not on the superbike.
Like the all the Japanese Turbo models of the early eighties. Turbos yes. Gaudy bodywork that meant hideously expensive bikes? No.
Lets start into the electron bike world with the fastest bikes with the longest ranges at the lightest weight. If they work bitchin’ people will buy them. Softening the transition for people that don’t “Get it”, could be provided by the sub-model or entry bike. The big daddy will be the one that functions best. If that means with or without a tranny, so be it.
todd says
I remember the price (and weight!) of the GTS1000 was well more than I was willing to shell out for even though I really liked the styling and tech. Instead, I looked around for a SRX600 and ended up with a GB500. Both those bikes did everything the GTS did but for MUCH MUCH less dough.
I imagine it’s the same now with electric motorcycles. I can’t see myself shelling out $10,000 for an unproven bike (I can’t seem to keep my phone or camera batteries charged either) with the performance of a decent 250. I can even pick up a clean GTS1000 for less than half that…
-todd
rohorn says
Features that electric bikes need to be familiar:
Tactile Speed Feedback ™ (AKA vibration, provided by offset motor rotor).
iKickstarter ™ (Hooked up to small generator to boot up controller computer).
E-Seize ™ (Motor controller randomly locks up motor during WFO events, because, well, we just like to keep it real).
E-Jets ™ (Motor controller doesn’t work right unless you move pin jumpers and dip switches around in a hard to reach place surrounded by high watt contacts that will shock you unless you double right click the iPetcock to “Off”. Controller can be upgraded with the iAmal ™ app that never works right no matter what you do unless it is cold and foggy outside – for added character that real manly motorcyclists crave).
Nah, this is just more proof that some electric motorcycle design world needs to pull its head out of its gas.
FREEMAN says
I’m no expert on any of this, but the guys behind this might be onto something. It appears that the transmission can also be used to “compression” brake, while at the same time, providing a charge to the batteries. It would be interesting to see some field tests on similar bikes with and without the transmission.
Bart says
Electric motors 101: The concept of “backEMF” or inductive kickback.
When an electric motor is “run” with electricity (applied voltage & some current flow) the spinning motor also acts as a generator. This effect is called back electromotive force (back EMF) and is a voltage that pushes back against the applied voltage, thereby reducing the net voltage across the motor’s windings. This effect increases with motor RPM. It is greater/lessor depending on motor type as well (perm mag/series-wound/ inductive.)
A tranny would allow the rotor to be spun faster across a wider range of speeds, and the motor would then have more “compression” effect due to back EMF (engine braking.)
One more secret: designing out as much of the iron in the field windings as possible helps reduce this effect, which is in general negative to the desired results of power & efficiency. This requires very careful field winding design and support. Water cooling is good too, keeps the coils from melting!
Learned all this the hard way in the 80’s on automated guided vehicles and DARPA unmanned vehicle projects. Is interesting to see the laws of physics haven’t changed since then.
If this tranny concept has any merit, I’d set it up with a small catalog planetary set off the end of the motor. Better packaging, more efficient for this kind of motor.
Thom says
Well, if we lot were so keen on innovations, even if they worked, why are most motorcycles still using telescopic forks? BMW gets away with their (admittedly stolen Hossack) “alternative” front end because they’re BMW, and known for making quirky bikes with high price tags. Bimota’s Tesi/Vyrus is viable because it’s only made in small numbers, with -again- a high price tag. The fact is, even if something IS better, if what you’ve got works well enough, or if the difference isn’t that great, people will stick with the established norm, regardless. Electrics may be the way of the future, but until they’re IMPRESSIVELY better (or until they’re cheaper) than an ICE motorcycle, they will only sell in small numbers.
This may be a bit of a step backwards, but sometimes you need to appeal to a certain sense of tradition before you can improve on the design and take a step forward.
I mean, does anyone remember how hard it was to convince people that belt-driven overhead cams were a good idea, when they required more maintenance? Progress can’t come too fast, or it won’t be accepted.
Decline says
I don’t know…If I remember right, Tesla tried a 2 speed transmission but couldn’t get it to last beyond a thousand miles or so. I’m sure there is some benefit from it, or a number of companies probably wouldn’t still be pursuing it…but I think we are more likely to see an electric engine transmission appear in a car first. Well a reliable one that lasts that is.
Chris Y. says
Decline, I’d like to note that Tesla was unable to do so because they were fairly incompetent in their engineering for the transmission (i.e. air cooled vs. water cooled like the founder they kicked out, Martin Eberhard, had suggested). Had they been successful, the vehicle would have had much better acceleration.
Fearnow says
We won’t know if it is a good idea or a dead fork in the evolutionary tree until someone fabs it up and wrings it out.
I for one am glad to see that electrics are getting the innovation-love.
Gregjet says
Some points that I thought may be relevant ( please note that I am not a qualified anything).
ALL motors will have hysterisis around the 0rpm point. ICE, electric whatever.
In the case of the electric motor in a motorcycle there will be included in the forces to overcome BEFORE the rotor moves ( in no particular order): internal coil resistance, wiring resistance/inductance, air friction, voltage resistance built up because of the load before moving caused by the heat increase, internal drive resistances and rolling resistance. So an electric motor cannot have max torque at 0 rpm in a real system.
Also the amount of heat generated by the load in the motor itself will increase the electrical power useage due to heat induced resistance increase . Positive feedback.
The answer is off course cooling. In most cases by air around the rotor. The optimium air flow ranges will occur at some speed for a passive (no fans, self pumping rotors, heat exchangers etc) or an active cooling. Thus a gearbox could have distinct benefits in keeping in that optimium operating range ( ie cooling flow /motor rpm).
NB. Those who may have seen other of my previous posts my think I work in a heat related occupation, but I just happen to live in the tropics where most things designed in the temperate areas of the world run into problems when you use them here .
One of the things forgotten in the limitation of power in electric motors is the closeness of the rotor and its coils/magnets. As the rpm increases the air between creates greater and greater drag as the velocity induced effective viscosity increases. Another one of those engineering compromises: the closer the gap the better the torque/power, but the greater the drag and heat build up ( and electrical resistance increase). So electrical motors will , like ICE’s, have an operating range. Ergo a gearbox could quite conceivable have a useful function when balanced off against extra gearbox friction ( and complexity).
My two cents worth for the arguement
Decline says
@Chris Y.
Seeing as how I’m on the internet I should just look it up….
I thought they had outsourced the transmission though and it wasn’t their design/engineering. But yeah, there is a fair amount of incompetence there.
e-bike builder says
I think much of this misses the point. We have built many e-bikes and the trade off is always acceleration vs. top speed because you have a single gear ratio – choose 5:1 get excellent acceleration at the sacrifice of top speed. Use a 3:1 ration and sacrifice acceleration for top end. What makes sense and we have done is a simple 2-speed transmission that allows both a high gear ratio for acceleration and a lower gear ration to achieve good top speed. I do not believe any more complex transmission is required. The conversation about motor size, battery capacity..etc misses the point about overall drive-ability and functionality of a real world bike.
Calven says
hey Guys!!! I aint no geniues on this stuff….But somethin kinda hit me wen i was reading this…..Now initial torque is best in Electric motors…Rite!!…And that is the reverse of the ICE’s we still have….Now as the transmission in our ICE’s balanced helped build torque at lower rpms…can they do vice versa to keep the electric motor speed at its best and use a transmission to gain the speed and power we need….I feel if properly worked out(mathematically) its does make some sense to me….Any takers!!
CycleDave says
Take any engine, ie:(two or four stroke piston, rotary, gas turbine, or electric) all have a specific max torque production at low or high and anywhere in between RPMs depending on the engine or motor capabilties. ICE’s do have to rev somewhat to produce a required amount of power but will eventually max out and taper off consuming more energy than necessary and becoming ineffiecient. Since an electric motor produces maximum torque at very low RPMs it would only make sence to have the motors power go through a transmission to keep it at or near peak torque as vehicle speed increases. If, for example, the electric motor produces its most effecient power at 1500 rpms, it wouldn’t be good to have it spin a let say 5000 rpms to mantain highway speeds. So put any electric motor to a transmission to keep speeds up and motor revolutions down to max out range on current battery technologies and maybe convince more people of the benefits. Plus IETs Idea REALLY intrigues me.
yz400 says
I have yet to see someone bring up the approach of energy savings. If you add the transmission the torque to start is multiplied so the twisting of the throttle is reduced saving you battery. In the later gears when the bike is running 1:1 the saved energy will help to increase range. Getting gobs of torque in the start without much throttle sounds pretty good. I look at battery usage more than what power is being generated. What is so great about making a lot of torque if the battery goes dead right away. Isn’t the point to have as long a ride you can while still enjoying the bikes capability?
mod says
the transmision is a stepping stone to map the feel we want to achieve from the bike. it will allow us to dial in the nuances of acceleration, torque, efficiency, and speed, and map the ideal physics to an algorithm for the control system. the ultra efficient electron bike of the future will have very few moving parts and be as light as possible, i.e. no gears. you like to shift? thats like saying you miss being able to hand crank your ICE.
David says
since I ride a woods bike, a KTM 300EXC, I have been looking at electric bikes for that purpose. The idea of a gearbox on a bike makes very good sense to me. It is hard to get a motor large enough into a trail bike to get the torque needed for large hills and this can be easily done with a gear box and once you are over the hill you are no longer tied to that lower ratio in the high speed portions. With the limited voltage that is available in a battery pack that will fit on a bike the trans helps make up the difference. The weight penalty is minimal because now you can get big torque with a smaller motor and I think the trade off is well worth it. Even the factory built cars that are able to use a single speed have fairly high voltages and there is just not the available room on a bike to carry that many batteries. Also, it certainly does not hurt for a company to try something different. If you don’t like gears, buy a different bike. That simple.
john says
I think David is on the right track: Mechanically or digitally accomplished, having another way to manipulate the power and breaking of the bike is valuable. Why has no one mentioned ‘backing it in’?