Conclusive proof gearboxes are awesome.

[Bike Xing]

A lot of restrictions that might be imposed on a race have a logical basis.
Max weight of 45 lb: I can pick it up over a fallen tree in the trail, walk up stairs, not exceed the limit of my car mounted carrier, actually pedal it home if I do run out of juice.
Max voltage of 33 V: Less risk of electrocution should something go wrong. I like to ride in wet conditions and there's less chance of melt down with a 33 V limit.
I could go on. The limits are not arbitrary.
My bikes performance in many respects is modest, but it works for my "race." I have not come across an ebike without a transmission that can do these things. Maybe you have?
To recap on what I want:
45 lb max
33 V max
Full suspension for off road control
Ability to climb up to 45% grade with 180 lb rider (stopping for FET's to cool down is not acceptable)
20 mph cruising speed on level ground
20 mile minimum range in extremely steep terrain
Reliable
Decent weight balance so I can pick it up

Instead of going straight to "the" race track it would be nice to have a giant matrix that showed what component specifications resulted in what capabilities.

 

[speedmd]

50-55 pounds is more realistic for a ebike with some range and still be durable without breaking the bank or going to a bunch of carbon parts. No limits on voltage. "Run 220 -221, what ever it takes". :lol: :lol:

IMO, The motors (and controller) Power Band is key to this argument.

 

[bobb]

Describe the race where the gearbox over a properly sized motor is helpful. Is it a race where the first part of the race is a tractor pull, and the second part is a top speed event?


I thought a fantastic example recently was watching the pikes peak race. Lightning crushed everything on two wheels, and part of that was not wasting it's time shifting, but instead always having the ability to apply as much power to the rear wheel as you request simply by twisting your wrist.

Pikes Peak sounds awesome. Same bike, same motor, same battery, except I have a Thud titanium/carbon/ceramic 2 speed.

Oh and one other minor change. The top is halfway. Now we have to race back to the bottom.

I'll be in the bar.

What am I missing

and sorry to all who had hoped this thread had finally died.

 

[efMX Trials Electric Freeride]

production, testing and a look inside the SMRE emoto transmission:
[youtube]rOZIK_Kgfhg[/youtube]

 

[Chalo]

To recap on what I want:
45 lb max
33 V max
Full suspension for off road control
Ability to climb up to 45% grade with 180 lb rider (stopping for FET's to cool down is not acceptable)
20 mph cruising speed on level ground
20 mile minimum range in extremely steep terrain
Reliable
Decent weight balance so I can pick it up

There are several requirements in conflict with each other here. A 45 pound e-bike with full suspension and enough power to climb a 45% grade and enough energy go 20 miles in steep hills? After the bike is accounted for, that leaves a weight budget of about 15 pounds for motor, battery, controller, wiring harness, and mounting hardware. Good luck finding a 15 pound e-kit that has enough potency to hit even one of your performance targets. And you want it reliable? Why not add a requirement that it should cost under fifty bucks while you're at it?

You could throw a few thousand more dollars at the bike and reduce its weight by like three and a half pounds. Then you'd have an 18-1/2 pound weight budget for an e-kit that still doesn't meet your performance goals. But your wallet will be a lot lighter!

Unrealistic weight criteria are likely to result in a bike that isn't actually good at anything except meeting the weight limit. My advice is figure out how to make it do what you want, don't use needlessly heavy components or any unnecessary parts, and let it weigh whatever it weighs.

 

[zEEz]

I guess the street ebike Brammo Empulse was-is supposed to be available either single and multispeed.
I saw different prototypes. Probably the point is more to have something to differentiate from
the existing market offer, then something making sense, practically.
On the other hand, how it is possible to revvv up at the red light, otherwise?

have fun!

 

[John in CR]

I guess the street ebike Brammo Empulse was-is supposed to be available either single and multispeed.
I saw different prototypes. Probably the point is more to have something to differentiate from
the existing market offer, then something making sense, practically.
On the other hand, how it is possible to revvv up at the red light, otherwise?

have fun!

Their race bikes are single speed, and that says it all. Tesla's are single speeds. Zero emoto's, which won last year's Pike's Peak Race, are single speeds. Even train locomotives are single speed. We all dream of multi-speed gearboxes at first, but that's quickly forgotten as soon as you get on a bike with a properly sized motor.

 

[zEEz]

We all dream of multi-speed gearboxes at first, but that's quickly forgotten as soon as you get on a bike with a properly sized motor.

unfortunately I need to revv up endlessy at the red light, to feel happy
perhaps a magnetic clutch would suffice
Joke apart, most of the people needs in the developed world are connected to advertisement
and covert ad in series and films ... until fast and the furious will show gears, nitrous and so on,
instead of a tesla doing wzzzzzzzzzzzz ... of course test drive a vehicle can eliminate dubts, but
still a lot of peoples will perceive it as a lack of fun factor, because not everybody is looking
to ultimate performance or utility ... how to explain otherwise the legions of happy bikers riding
things that are eating up more fuel than a pickup, not capable of steering, etcetc ...

have fun!

 

[John in CR]

Those people can ride the bus until they get over their need to make noise pollution.

 

[speedmd]

Their race bikes are single speed, and that says it all. Tesla's are single speeds. Zero emoto's, which won last year's Pike's Peak Race, are single speeds. Even train locomotives are single speed. We all dream of multi-speed gearboxes at first, but that's quickly forgotten as soon as you get on a bike with a properly sized motor.

Hi John

Agree you need the right size motor to drive from zero rpm in a gear tall enough to get good speed. Question I have is, how does one get there with a smaller affordable motor/ controller and not be limited to using high voltage and give up some efficiency on the low rpm side. Most of the standard motors I have been playing with will top out at around 3000 -3300 rpm with their design voltage. How does one get them to rev up to say 6000 -8000 rpm without loosing the efficiency at the lower RPM ranges or going to 24s - 28s or such or go to some fancy control method without getting killed with eddy current losses. If something like a little GNG motor were run 4 or 5 to 1 to the rear wheel, it would easily pull off the line and pull strong, but top out at a relatively low speed with 48 volts. Shifting into a "electrical" high gear would solve the gearbox quest. Don't know of any cheap / easy way to do it, but interested just the same.

cheers

 

[gwhy!1]

single speed is a easy but expensive way to get high performance .. I think the real problem is there is nothing on the market that can handle the torque of a performance electric setup and nobody really wants to develop a gearbox that can handle it . Developers with money will always fit the biggest motor/controller/best batterys to cover the performance instead of investing loads of cash developing a gearbox that will withstand all the torque .. tesla stopped using the 2 speed gb due to reliability problems and as it only gave a extra 30-40mph on top of what was already a very fast car nobody seemed to mind. A race car that is being developed in the uk produces 4000Nm of torque and is capable of over 200mph from a direct drive system , just imagine trying to develop a gb that can handle even a third of that amount of torque.

 

[zEEz]

e .. tesla stopped using the 2 speed gb due to reliability problems and as it only gave a extra 30-40mph on top of what was already a very fast car nobody seemed to mind. A race car that is being developed in the uk produces 4000Nm of torque and is capable of over 200mph from a direct drive system , just imagine trying to develop a gb that can handle even a third of that amount of torque.

I agree with your points, but for the tesla case I suspect time to market went against developing effort, in order to hit in time for the big boom. If they really want to make a 400 kmph supercar, perhaps some kind of dual final ratio, selectable only from a dead stop, could make a sense, perhaps just in theory (something like an Insane Mode button). Definitely I would not want the possibility to have ratio change during drive, considering the ultra complex torque management system.

have fun!

 

[liveforphysics]

Every power transfer is loss.

You can not add things in series with your motor and end up with more power.

If you find yourself in a situation with a motor that doesn't deliver the performance desired when used direct-drive, you chose the wrong motor for the application. The solution is not to add more losses and complexity, the solution is to chose an appropriate motor.

 

[gwhy!1]

Every power transfer is loss.

You can not add things in series with your motor and end up with more power.

If you find yourself in a situation with a motor that doesn't deliver the performance desired when used direct-drive, you chose the wrong motor for the application. The solution is not to add more losses and complexity, the solution is to chose an appropriate motor.

nobody is on about more power .. it more about optimising the power that is available for the price bracket .. losses and complexity is mainly down to design and nobody have come up with a solution..

 

[liveforphysics]

Did you miss Mile's direct drive hub motor design my friend?

Grow it's width to suit your applications power needs.

It has less total system losses than a single stage of gearing alone.

 

[gwhy!1]

Did you miss Mile's direct drive hub motor design my friend?

Grow it's width to suit your applications power needs.

It has less total system losses than a single stage of gearing alone.

I guess i must have missed it ... but this is still not in production so its not cheap.

 

[speedmd]

Did you miss Mile's direct drive hub motor design my friend?

Grow it's width to suit your applications power needs.

It has less total system losses than a single stage of gearing alone.

Great point Luke. Now, how would we get the thing to spin higher RPM and not loose its low RPM efficiency. When we first started the design miles asked about what we wanted for a max RPM. We chose 400 rpm as it would need to be high torque/ direct drive and light weight still. Using that motor in a mid ship arrangement with a 2 or 3 to 1 reduction, it would be killer if it could spin up to 2000 rpm or so, just by using the controller side to get the rev range. Wishful thinking?

 

[liveforphysics]

Did you miss Mile's direct drive hub motor design my friend?

Grow it's width to suit your applications power needs.

It has less total system losses than a single stage of gearing alone.

I guess i must have missed it ... but this is still not in production so its not cheap.

The fact that the current state of cheap volume production product offerings lacks optimized motor designs does not change the reality that gearboxes have no place in EVs.

It does however highlight how immature the EV industry is at this point in time. I look at it like the early 1900's of internal combustion. Some people are still saying they will never replace a good horse. Some are saying steam power is the future. Some are saying we need to add more pointless complexity and loss to a propulsion system who's single greatest attribute is needing none on it.

 

[liveforphysics]

Did you miss Mile's direct drive hub motor design my friend?

Grow it's width to suit your applications power needs.

It has less total system losses than a single stage of gearing alone.

Great point Luke. Now, how would we get the thing to spin higher RPM and not loose its low RPM efficiency. When we first started the design miles asked about what we wanted for a max RPM. We chose 400 rpm as it would need to be high torque/ direct drive and light weight still. Using that motor in a mid ship arrangement with a 2 or 3 to 1 reduction, it would be killer if it could spin up to 2000 rpm or so, just by using the controller side to get the rev range. Wishful thinking?

Wind it as a single turn motor, perhaps HVH style bar-in-slot winding like the modern Remmy stuff used in the Volt and others.

Then the weak-link is no longer the motor, it is in finding a controller with the capability to drive it to it's potential. Make that controller, and you can stay in non-lethal voltage ranges, have your brutally delicious and extremely efficient low-RPM torque cake and eat your high RPM's power needs too.

 

[speedmd]

finding a controller with the capability to drive it to it's potential.

Exactly! Now where do we find the treasure map for the controller? :lol:

 

[zener]

Did you miss Mile's direct drive hub motor design my friend?

Grow it's width to suit your applications power needs.

It has less total system losses than a single stage of gearing alone.

I guess i must have missed it ... but this is still not in production so its not cheap.

The fact that the current state of cheap volume production product offerings lacks optimized motor designs does not change the reality that gearboxes have no place in EVs.

It does however highlight how immature the EV industry is at this point in time. I look at it like the early 1900's of internal combustion. Some people are still saying they will never replace a good horse. Some are saying steam power is the future. Some are saying we need to add more pointless complexity and loss to a propulsion system who's single greatest attribute is needing none on it.

I agree 100%
Its pointless to produce bicycle specific frames with inegrated geared middrives like bosch yamaha ect. do. All they do is make there customers depending to buy more stupidly expensive replacement equipment from them.
But sadly the people actualy like it.

Its a race between stupidly enginered planed obsolescence.
And DD hub or rim magnet axial flux. :lol:

 

[gwhy!1]

the point I am trying to make is why do someone need a hub motor that is nearly 3x times heavier and bigger and that needs to run on 2x the voltage to do around 50mph with the acceleration comparable to a much smaller/lighter motor running on a lower voltage but with a small addition of a bit of hardware ( total weight and size still comes in half the weight of a hub ). I get the whole additional complexity thing as a major down side but why cant someone have even better acceleration and also keep the same top speed all from the same small/light/cheap package , maybe there will not physically be enough room to fit a motor/controller/batteries that someone requires for the performance they are looking for, so then what ? make the something even bigger that you are fitting it to. Im sure in time Tech will get better and prices/sizes/weights will drop but as it is now its still to expensive and if nobody looks for alternatives it will always be expensive and nothing will change.

 

[gogo]

…
Its pointless to produce bicycle specific frames with inegrated geared middrives like bosch yamaha ect. do. All they do is make there customers depending to buy more stupidly expensive replacement equipment from them.
But sadly the people actualy like it.

Its a race between stupidly enginered planed obsolescence.
And DD hub or rim magnet axial flux.

Marketing is like a microorganism that replicates and mutates into a form that eventually alters its host's emotional behavior to voluntarily offer up cash.

People are comfortable with the idea of gearboxes and changing gears. To the casual observer automobiles have improved through increased numbers of gears in their transmissions, therefore to them more is better. Its only engineers, people who didn't sleep through physics class, and a few people who have experienced continuous torque propulsion that understand why a properly sized DD electric motor is the elegant solution.

Most people are going to need a demonstration test ride before having an emotional "Oh, this is better" experience to bring them around to DD. Even then the mass market will be dependent on finding the effective emotional hooks to complete the sale.

 

[liveforphysics]

Miles motor is not heavy.

Think of your small motor and a 10:1 reduction stage. Now think of your small motor simply grown in radius to give you the 10:1 torque increase you desired (which only needs to grow to ~3.2x radius), and now you have your same small motor + gearing stage system performance, but with more area to shed heat from active motor materials and none of the losses of the gearing stage.

Think about this. You ultimately want a torque at your drive wheel. There is an infinite variety of methods to arrive at that torque. Do the methods become better or worse as you add additional complexity?

You can have your equivalent effects of gearing by just growing radius. The magnets move past the teeth faster and they apply there force on a longer moment arm, the difference is, you don't carry around a bunch of non-active material mass and waste energy grinding gears together when you do it in one stage.

I agree that today the market is badly lacking in ultra light weight very high efficiency/performance direct drive hubmotors. That does not change the fact that it is the ultimate drive solution, only that people are currently choosing to settle for less.

It took building deathbike for me to finally realize a multi speed transmission in an EV is a folly. Once you experience more torque than you can possibly apply even in the best of situations, while holding this unusably extreme torque all the way to a top speed you don't have the balls to reach, you realize immediately that any other nonsense like needing to change gears is just wasting your time, and giving your power train new and unnecessary failure modes.

I'm in China at the moment, but I will be back soon, and if you ever visit Santa Cruz I will let you ride deathbike and you will immediately gain awareness that all the transmission related BS was just noisey parts grinding around on each other in a box rather than something to be desired in an EV drivetrain.

 

[speedmd]

While the ideal of a ultra light weight super high power dd hub motor is in the dream stages, we can enjoy the benefits of mounting many existing excellent motor designs mid ship with one efficient quiet reduction stage. As on the zero. This is not all down side as it will greatly benefit bike balance and reduce the un-sprung wheel mass with all it's ills. It will also benefit with regards to reduced motor size/ weight and battery /controller requirements as mentioned. Certainly trade offs that seem well worth the efficiency losses at least at this stage of commercial motor availability.