Conclusive proof gearboxes are awesome.

[John in CR]

Toolman2,

You're talking about using the same motor for two totally different uses, so sure a difference in gearing can be worthwhile. The tranny better be light though, because a bigger motor can do both your mountain climb and road run as a single speed. What top speed did you need on the road? I ask because I'm building a trail bike to take big ole me up the mountain trails, and gearing it down to a top speed of 60-70kph will make the 10kg motor more than capable as a single speed, and that's with a 170-180kg all up load on 74V nominal. If it seems lacking, I'll just up the voltage and number of teeth on the driven sprocket. Since it already handles 20% grades with ease on the road, I'm pretty sure the planned 40% reduction will be enough. Then I can go up in voltage for an 80kph or higher top speed and still excel on the trails, or with a controller swap go to 30s instead of 20s, and split it with an additional 25% gear reduction and 25% increase in no load for an on and off road single speed beast.

The lack of an appropriate motor or gearing them too high or sending the stator too far into saturation account for most problems, not a lack of a gearbox.

John

BTW- The extra 3 teeth definitely won't make it more efficient, and often won't even give it more top speed. Instead simply use the 3 teeth lower gearing, use a higher voltage, and forget the tranny.

 

[gwhy!1]

Toolman2,

You're talking about using the same motor for two totally different uses, so sure a difference in gearing can be worthwhile. The tranny better be light though, because a bigger motor can do both your mountain climb and road run as a single speed. What top speed did you need on the road? I ask because I'm building a trail bike to take big ole me up the mountain trails, and gearing it down to a top speed of 60-70kph will make the 10kg motor more than capable as a single speed, and that's with a 170-180kg all up load on 74V nominal. If it seems lacking, I'll just up the voltage and number of teeth on the driven sprocket. Since it already handles 20% grades with ease on the road, I'm pretty sure the planned 40% reduction will be enough. Then I can go up in voltage for an 80kph or higher top speed and still excel on the trails, or with a controller swap go to 30s instead of 20s, and split it with an additional 25% gear reduction and 25% increase in no load for an on and off road single speed beast.

The lack of an appropriate motor or gearing them too high or sending the stator too far into saturation account for most problems, not a lack of a gearbox.

John

BTW- The extra 3 teeth definitely won't make it more efficient, and most likely won't even give it more top speed. Instead simply use the 3 teeth lower gearing, use a higher voltage, and forget the tranny.

if you can have a very strong, very efficient, very small, very light 2 speed gb with less than .5 sec shift would you not want that, Or would you still rather use a over sized motor with a over sized controller ( needed for those long steep climbs ).

 

[John in CR]

if you can have a very strong, very efficient, very small, very light 2 speed gb with less than .5 sec shift would you not want that, Or would you still rather use a over sized motor with a over sized controller ( needed for those long steep climbs ).

Very small won't do it. My only tradeoff is a bigger motor to get the lower more quiet Kv. I need the top speed of 100kph+. I need the steep hill climbing, though not a low speed with my bike fore the road. I'm not giving up the strong passing power at up 80kph+ . No less powerful motor will do what I want and need no matter what gearbox is attached to it.

The Model S didn't need a gearbox to beat the Viper. The Tesla Roadster didn't need a gearbox to beat all the sports cars it beat. Electric trains and trolley and subways don't have multi-speed gearboxes. Golf carts don't have them, and neither do big ships with the most powerful electric motors in the world, just like the giant mining trucks don't. Zero electric motorcycles don't have them either. None of the highest performing ebikes on the forum have multi-speed gear boxes.

The shift time could be zero and it won't make any difference. We already have more torque off the line than we can put to the road, so a gearbox will serve zero benefit. If I had less total load, then I could use a proportionately smaller motor for the same performance. If I wanted less to speed, I could use a proportionately smaller motor. If a higher rpm was acceptable to me, then I think that would proportionately decrease motor size too.

The problem is the in between motor doesn't exist yet, at least not for a nice price. You can accept lower performance as your compromise to use the smaller lighter system, but I'm not. Why would I want to just for the sake of a few Kg mounted down low?

John

 

[liveforphysics]

if you can have a very strong, very efficient, very small, very light 2 speed gb with less than .5 sec shift would you not want that, Or would you still rather use a over sized motor with a over sized controller ( needed for those long steep climbs ).

Personally, since I've broken nearly every tranny on every vehicle I've owned at some point, and since the shifting really upsets the chassis when you bang a gear while all leaned over in a corner, so much so that they make back-torque limiting clutches and things for superbikes to cause less disturbance, yet it still upsets the chassis enough that they have to lay-up on the cornering lean angle for a moment before they grab another gear mid-corner (or just try to never have to shift while mid-corner for 90% of corners), I would rather simply make the torque I'm asking for directly with no extra bullsh*t to break or fail or upset the chassis when I'm using it, etc.

If you want 400ft-lbs of torque on your rear wheel and a top speed of 100mph (or whatever your perfect world-bicycle would have for power), just pick a motor that can achieve that criteria directly, and it will be the ultimate best solution. This is why when you make a $2million dollar TTXGP bike like motoczyz or lightning or something wildly awesome like that, you don't see a transmission in the drivetrain, because they understand any weight/volume/bulk etc that they add to the bike would just yield better overall performance in every metric to just add that weight/volume/bulk to the motor directly rather than into a tranny to add a new string of losses for the pursuit of a mis-understood concept in the nature of motor efficiency. Make that motor bigger radius with more room for copper and make that torque you want more efficiently than is possible to do once you've added additional power transfer stages in the form of transmission gear drag/friction/windage etc.

If you're able to do it with direct drive, you've designed the best overall system from most any perspective, and you've got the highest continuous power as a result (because the motor is larger with more surface to dissipate heat etc).

You guy's know I used to be a huge fan of the tiny 10,000rpm motors running through big reductions and drooling over transmissions and things. I've learned a few things over the years of burning up most everything made though, and one of those hard lessons was that motor size is king in a performance application. If you want to abuse the snot out of it and make superbike stomping power on a bicycle, the path that yields reliable durable end results doesn't involve tiny high reving motors to make the power and create the torque multiplication through big reductions. This does work for bursts of relatively high-losses low-efficiency high-performance, and can yield a bike with a few pounds lighter weight than direct drive, but you're not going to end up with something you can beat on and not be constantly repairing it's plethora of exotic failure modes that happen. (nobody knows this better than folks like myself and Thud and Matt who've been building systems using this method for some years now).

Big slow turning elephant lifting torque is the path to highest ultimate performance and durability and efficiency IMHO. This is why it's what you use in a situation like a million dollar budget solar car where you're fighting for any 1% efficiency change that will make the difference between winning and loosing. It's only inefficiency when you look at some bullshit on a graph without understanding the nature of the losses addition that forms the efficiency curve.

 

[gwhy!1]

Im not saying give up your your monster motor.. just be a lot more efficient , still your bike will be able to do what you want it to do but with saving weight and cost on a controller and battery ah's . The EV TT bikes are not geared but why dont you think they do not have such high top speed as a ICE bike .. its because its a compromise between speed, power and range, if a very small light weight gb was incorporated into a TT bike then it can then have the same top speed as a ICE bike without some of those compromises it will also have much better ah eco when its doing the twisties ( on/off the throttle ). Yes a direct drive makes it very simple but it can be improved upon.

 

[John in CR]

"Big slow turning elephant lifting torque".

I love that description. Luke, we have to remember that these guys have never experienced throwing their leg over something with sufficient electric power/torque to weight to achieve that continuous pull up to the speed they desire. I'm lucky that I don't need the same speeds or torque to the excess that Luke craves, so I'm able to get my thrills cheaper and easier.

 

[gwhy!1]

if you can have a very strong, very efficient, very small, very light 2 speed gb with less than .5 sec shift would you not want that, Or would you still rather use a over sized motor with a over sized controller ( needed for those long steep climbs ).

Personally, since I've broken nearly every tranny on every vehicle I've owned at some point, and since the shifting really upsets the chassis when you bang a gear while all leaned over in a corner, so much so that they make back-torque limiting clutches and things for superbikes to cause less disturbance, yet it still upsets the chassis enough that they have to lay-up on the cornering lean angle for a moment before they grab another gear mid-corner (or just try to never have to shift while mid-corner for 90% of corners), I would rather simply make the torque I'm asking for directly with no extra bullsh*t to break or fail or upset the chassis when I'm using it, etc.

So what if there was a GB that could survive the torque and had a super smooth predictable seemless shift without no jolt through the chassis or the drive train, would this be workable. Just cos nobody has designed a good GB yet that can be used with electric motors in the EV world dont mean that the thought of the use of a GB should be ignored just on the basis of there isn't a GB that is up for the job.

 

[Arlo1]

if you can have a very strong, very efficient, very small, very light 2 speed gb with less than .5 sec shift would you not want that, Or would you still rather use a over sized motor with a over sized controller ( needed for those long steep climbs ).

Personally, since I've broken nearly every tranny on every vehicle I've owned at some point, and since the shifting really upsets the chassis when you bang a gear while all leaned over in a corner, so much so that they make back-torque limiting clutches and things for superbikes to cause less disturbance, yet it still upsets the chassis enough that they have to lay-up on the cornering lean angle for a moment before they grab another gear mid-corner (or just try to never have to shift while mid-corner for 90% of corners), I would rather simply make the torque I'm asking for directly with no extra bullsh*t to break or fail or upset the chassis when I'm using it, etc.

So what if there was a GB that could survive the torque and had a super smooth predictable seemless shift without no jolt through the chassis or the drive train, would this be workable. Just cos nobody has designed a good GB yet that can be used with electric motors in the EV world dont mean that the thought of the use of a GB should be ignored just on the basis of there isn't a GB that is up for the job.

Gwhy. If a bigger motor gives you the same results why bother?

 

[gwhy!1]

but a bigger motor dont give you the same results.. otherwise e-TT will be clocking up the same top speeds as ICE TT and doing the same distances.

 

[Thud]

lol,
4 pages of people talking right past each other.
set a few parameters.....like vehicle weight. & performance envelope.

As Biff mentioned, there is a place for multi speed transmisions in the ev world.
I doubt we would every need more than a 2 speed for 99% of on-road applications.

 

[Miles]

Phew.... Thanks Thud

 

[liveforphysics]

but a bigger motor dont give you the same results.. otherwise e-TT will be clocking up the same top speeds as ICE TT and doing the same distances.

The MotoCzyz bike can do the same speeds, and DID do the same speeds in a practice run down the straight just to show the world it's able to do it. The reason it couldn't do it in the race was 100% entirely up to battery capacity limitations and unrelated to the performance limitations of the motor/controller system power or RPM range etc.

Lightning's bike just crushes gas bikes in acceleration up to speeds beyond what my GSXR-1000 can achieve, and does it with a single speed, both effortless power wheelies off every corner exit. I've had Barney give me a quick thumbs-up wave doing a power wheelie coming off a corner at at least 70mph effortlessly lofting the wheel of this ~500lbs monster machine at a TTXGP. These things don't entirely sink-in looking at graphs on paper, but sink in pretty solidly when you're there feeling the wind on your face as this screaming 500lbs monster rushes past you making only a primal chain-noise scream with it's tire lofted in the air as it goes by. Experiences like that happen to you enough, and you start to realize, OHHHH, that's what I want to be doing, how is he doing that? Really big motor and direct drive? Hmm... That path seems to be offering the experience I'm looking for.

 

[Chalo]

I think the point is that you can attain the same performance with a single speed system as you can with a multiple ratio transmission system, just not with the very same motor and controller. The single speed system promises simpler operation and higher power efficiency when executed correctly, and the mechanical transmission promises versatility and easy configurability to meet different requirements.

Both approaches are valid when addressing the issues of performance, efficiency, user experience, etc., and both will claim successes in due course. If I were making a business plan or choosing an investment in a business to serve the mass market for transportation, I'd favor the single speed approach. It's a better match for a user who doesn't care exactly how the thing functions, and who depends on it to work straightforwardly all of the time. If it also makes a better race machine, that' s just one more benefit.

 

[Thud]

Really big motor and direct drive? Hmm... That path seems to be offering the experience I'm looking for.

your already there LFP

But seriously, the bigger motor=bigger performance works fine on road.....but take it off road & where are you?
the e-trails bikes are right on the cusp.....& the zeros look like a good play bike & would be fun against each other
BUT-
There isn't a single Ellectric off road motorcycle on the market yet that will lap with any ice off road bike on a closed motocross course.....to conqure the terain & have a resonable weight & still deliver the required tourque envelope, I see a 2 speed transmision....or some very advanced active cooling systems. or both.

& I won't mention bicycles in this reply....Thuds new definition of a "bicycle": you have to be able to cary it up a flight of stairs. everything else is a moped.

edit : punctuation baby!

 

[John in CR]

There isn't a single Ellectric off road motorcycle on the market yet that will lap with any ice off road bike on a closed motocross course.....to conqure the terain & have a resonable weight & still deliver the required tourque envelope, I see a 2 speed transmision....or some very advanced active cooling systems. or both.

& I won't mention bicycles in this reply....Thuds new definition of a "bicycle": you have to be able to cary it up a flight of stairs. everything else is a moped.

One lap should be relatively easy, but the 6 or 8 required isn't possible due only to batteries, and nothing else. We've gotta get a more appropriate motor in your hands to see the light. Comparing a Zero to them isn't fair, because they elected to go for similar or greater range, and with a safe long-life battery their power level required truly useful capacity anyway. With the much lighter load and lower performance requirements I think an offroad single speed emoto for kids has a chance at hanging with the gassers.

BTW, I can carry my bike up a flight of stairs, but I call it an ebike, not an e-bicycle. An ebike is anything with 2 wheels and an electric motor, and I don't care what it's called legally. That covers the entire spectrum. The more useful power the better and the lighter the better as long as you have the range you need.

John

 

[gwhy!1]

Sorry Luke and John I either have not explained it very well or you are not reading what I have wrote... I did not say that a direct drive electric bike can not go as fast as a gas bike of course it can but at a cost, which you have both acknowledged but are both choosing to ignore.

 

[liveforphysics]

Sorry Luke and John I either have not explained it very well or you are not reading what I have wrote... I did not say that a direct drive electric bike can not go as fast as a gas bike of course it can but at a cost, which you have both acknowledged but are both choosing to ignore.

The cost is NOT inefficiency if that's the cost you're toting. The energy used vs work done with large slow turning motors is actually very good in most situations. It's a huge misconception you're propagating to claim it requires more battery to get the same job done etc.

 

[gwhy!1]

Sorry Luke and John I either have not explained it very well or you are not reading what I have wrote... I did not say that a direct drive electric bike can not go as fast as a gas bike of course it can but at a cost, which you have both acknowledged but are both choosing to ignore.

The cost is NOT inefficiency if that's the cost you're toting. The energy used vs work done with large slow turning motors is actually very good in most situations. It's a huge misconception you're propagating to claim it requires more battery to get the same job done etc.

The cost is more ah to accelerate with a direct drive , not more ah for top speed .

 

[bearing]

There isn't a single Ellectric off road motorcycle on the market yet that will lap with any ice off road bike on a closed motocross course.....to conqure the terain & have a resonable weight & still deliver the required tourque envelope, I see a 2 speed transmision....or some very advanced active cooling systems. or both.

Are you sure? I read about an electric motocross bike that, according to the article, consistently beat 250 4-strokes. Don't remember which one it was though.

 

[liveforphysics]

Sorry Luke and John I either have not explained it very well or you are not reading what I have wrote... I did not say that a direct drive electric bike can not go as fast as a gas bike of course it can but at a cost, which you have both acknowledged but are both choosing to ignore.

The cost is NOT inefficiency if that's the cost you're toting. The energy used vs work done with large slow turning motors is actually very good in most situations. It's a huge misconception you're propagating to claim it requires more battery to get the same job done etc.

The cost is more ah to accelerate with a direct drive , not more ah for top speed .

You know what happens if you take the same motor, and you hook it to a transmission, and you start out in 6th gear vs starting in 1st gear right? If it has the torque to chug the load you've asking in 6th gear, then 6th gear will almost always be the lowest amount of energy to make that torque at the wheel. Once you start getting RPM, you have to pay for that torque with increased BEMF rather than merely paying the copper losses (which are often smaller than you might think), and the power you're drawing adds up very quickly as you accelerate.

 

[Thud]

There isn't a single Ellectric off road motorcycle on the market yet that will lap with any ice off road bike on a closed motocross course.....to conqure the terain & have a resonable weight & still deliver the required tourque envelope, I see a 2 speed transmision....or some very advanced active cooling systems. or both.

Are you sure? I read about an electric motocross bike that, according to the article, consistently beat 250 4-strokes. Don't remember which one it was though.

Find that article, Id love to read it. If the bike is light enough to ride a full lap at race speeds...I can see electric as a great option..... Until then, I am from Missouri.
Arlo, pmed me something about an article also,....but I am a motocross purest.....if they were just running starts I'll lmao. & wait for the day I don't have to listen to the roar of them damned able 4 strokes...

 

[gwhy!1]

LFP you got access to the equipment the same as me, just do some simple tests on the dyno for yourself , if you come up with different results than me then we will just have to agree to disagree .

 

[Hillhater]

Hillhater- Its not using a lot of power to be ripping up the asphalt right from a start.

Its likely getting 20:1 or 30:1 leverage on its phase current to battery current used as its starting out. This is because its only loss is the same loss its having when its making this amount of torque in its peak efficiency range, only now it has even less losses, cause its not having all the additional core losses of turning while its making this torque.
.

In simple terms , are you saying the Tesla is making maximum torque from standstill, yet not pulling max amps from its battery ??

 

[Arlo1]

Hillhater you have battery amps and phase amps mixed up. I will try to find a video later of one of my dyno runs that shows battery amps and they start at a low number and climb as the motor revs higher. The phase amps stay the same until almost full rpm but the battery amps climb from next to 0 at zero rpm.

 

[John in CR]

Once you start getting RPM, you have to pay for that torque with increased BEMF rather than merely paying the copper losses (which are often smaller than you might think), and the power you're drawing adds up very quickly as you accelerate.

That isn't fair is it, since it's the BEMF that helps them keep the phase currents under control, or am I looking at it wrong?