CVT getting closer

[Waynemarlow]

Constantly variable transmission set around the mid motor is on its way. Note the 200Nm, way over the top and I wonder what it weighs

 

[EME]

@Waynemarlow I thought it was quite interesting. Then I heard it described as the same as used in hybrid-powered cars for some time. I assume that means Lexus et al . I sincerely hope not, the thought of a total variable output, which both seems and is random despite changes in input input ( the accelerator pedal in a Lexus, my own graft on an eeb) has a wail of despair from me.

I must be missing something?

 

[Waynemarlow]

I don't consider this a true CVT more a development on a planetary gear system. You only need to control the rotational speed of the star gears electronically and you can have as many fixed gear ratios as you want.

 

[Tim1023]

My wife's Rise & Müller Nevo 3 has the Enviolo drive. Definitely continuously variable. Has an interesting mechanism:

 

[flash]

Every CVT car I've driven I've hated. Despised. Sure I'd feel the same way on a bike. Nothing wrong with gears.

Gordon

 

[Sidepod]

 

[DrStupid]

Been waiting a while ?. Anybody know when we can buy a FS emtb? And what price?

This Rev1 thing will not feel like the rubber-ball, rubber band , or auto-clutch CVTs. The physical connection to the system should- in possibility- feel as good as the current emtb assist motor/derailleur cassette systems, with the benifits of dumping the external bits.

This feels like the right direction. I just wish they would hurry ... up!

 

[Quinterly]

Every CVT car I've driven I've hated. Despised. Sure I'd feel the same way on a bike. Nothing wrong with gears.

Gordon

^This. CVTs are a bloody abomination in a motor vehicle application. Can not imagine how it would be better for a bike.

 

[Tim1023]

I have to say I really don't like it when I ride my wife's bike. And not only because it is a grip shift. Just don't like the vague feel of it. It also feels like it has massively less range than my Levo. But then again, it doesn't really need it. My wife loves it and it suits her needs perfectly! Also means less maintenance for me.

Enviolo also has an automatic system that senses what you need automagically. I don't think I'd like that at all, but horses for courses and all that.

I guess the question here is whether it has it's place on a mountain bike. For me not, but it might help some people to stop mashing their gears!

 

[Sidepod]

It should be an easy step to make the SRAM electronic shifter talk to the bike ECU. There is already a torque sensor in the motor so use it to control the rear mech.

 

[NoPro]

continental had a ebike mid motor with cvt but it is already discontinued

Continental Unveils Revolutionary 48V eBike System

48V Revolution is the world’s first 48V-powered e-bike motor with a fully integrated stepless automatic transmission contained in an all-in-one drive unit

www.continental.com

 

[OldBean]

I have been following this for some time in my anti derailleur campaign.
Earlier press releases described a “flappy paddle” type system where one can be fully auto or set it to manual gear changing with preset ratios.
My reservation is the “over” technology of the system as some of us oldies have trouble with TV remotes let alone setting up bike gears !
Need more info and a test ride.

 

[Straker]

The nuvinci hubs cvt hubs work really well, I had one on a cargo bike and it was stepless and smooth to operate.... although it was hideously heavy

 

[tophies]

I think that belt/chain driven CVT (prone to breaking) are not as good as eCVT such as the Toyota, which uses motors to change the ratios, good video showing how it works if your interested - if this could be miniaturised to fit ebikes then maybe this would be the way to go?

 

[Quinterly]

I think that belt/chain driven CVT (prone to breaking) are not as good as eCVT such as the Toyota, which uses motors to change the ratios, good video showing how it works if your interested - if this could be miniaturised to fit ebikes then maybe this would be the way to go?

The problem with CVTs is that they are designed around the concept of keeping engine RPMs constant and varying the gear ratio. In theory that concept is efficient in a motor vehicle. However, it destroys driveability, compromises handling, and (as you point out) has reliability issues.

However, even assuming that they are fine in a motor vehicle (or even a motor bike) application, on a mountain bike there is zero ability for a rider to keep pedaling speed constant destroying any theoretical advantage that a CVT might have. There is no substitute for actual gears ... e-shifting can obviously lead to automatic shifting if that's what a rider prefers, but a CVT is just an inherently bad concept for a mountain bike (e-MTB or acoustic).

 

[urastus]

CVT in motor scooters is amazing. There is so much more available power, and much less weight. The big downside is no engine braking - kind of like an emtb.

I did come across this shaft drive system with gears - it is still in it's infancy

 

[Cory S]

Drivetrain efficiency is terrible with CVT's. The power loss to the ground/wheels is huge.

 

[DrStupid]

I wonder what the trouble is with the Revonte? Is it investments, sabotage, or does it just suck? It should have been here by now.

 

[geemy]

Every CVT car I've driven I've hated. Despised. Sure I'd feel the same way on a bike. Nothing wrong with gears.

Gordon

eCVT seems to be the best transmission for parallel hybrids..toyota/Honda/ford. you can combine the gas engine and electric motor power, run on pure electric, do Regen, or charge the battery, smoothly switch between those different modes while simultaneously acting as a reliable and efficient CVT without belt, and ECU has full control over the rpms to continuously optimize power or efficiency like cvts with actuators (unlike scooter/mopeds using weights/springs that you need to tune with a compromise between acceleration/top speed/efficiency) no shifts/ loss of power but you can also simulate gears in manual mode.
it's virtually a "perfect" transmission for the job it has to do on an hybrid, optimizing performance and efficiency.


transferring this technology to mid drive ebikes has a lot of advantages. "shifting" under full load is not a problem, will default to shortest hearing from a stop, combining mid drive motor and low maintenance transmission protected from water/dirt/shocks by a sealed metal casing, while keeping the rear wheel as light as possible, no chain slap and you can use a belt.
the issues I see is first it's maybe a bit complex for a bike(two motors), and second the automatic mode while allowing you to always maintain a good cadence, will probably not feel natural for experienced riders. but they also have an electronic shifter and virtual gears. the weird catch is the range and longest gearing possible : 440% at 60rpm and the fact the that the longest gearing is not fixed and depends on your cadence which I agree must feel awkward when you are at top speed. pedaling faster will actually reduce the gearing. but the benefit is that you can also pedal slower and benefit from a longer gearing. otherwise the usual concerns that people have over cvts : engine reving too much under acceleration or at highway speeds and the fact that rpms stay constant under load don't apply to ebikes because automatic mode will be tuned for human pedalling, not the Atkinson engine found in hybrids, your legs don't make sound, and you'll always have the choice of manual mode, with full control and added benefit of near instant shifts under full load, no cutting motor power. the shortest gearing will be too low to do technical mtb climbs with usual cadence of a granny gear, but you will still be able to climb while pedalling slowly, with the help of 200Nm pedal assist.

 

[geemy]

Drivetrain efficiency is terrible with CVT's. The power loss to the ground/wheels is huge.

ecvts don't have a belt rubbing power and potentially slipping. plus you have a perfect chainline all the time unlike 1x12 losing lot of efficiency when using short/long gears.
also let's be real you don't buy 2000W/200Nm ebike to use it on pedal power alone. efficiency is still important for range, but it supposedly has same drag as any ebike and if you ever hit 0% battery the transmission will just be stuck in low gear (60rpm/10mph) which sound alike a decent compromise ( have you ever tried pedalling an ebike without assist in top gear?)

 

[geemy]

CVT in motor scooters is amazing. There is so much more available power, and much less weight. The big downside is no engine braking - kind of like an emtb.

I did come across this shaft drive system with gears - it is still in it's infancy

the motors are able to Regen, like any electric motor
the usual freewheel mechanism in the rear hub simply does not allow to transfer any torque to the mid drive. you need to move the freewheel to the crank, and make the chain/belt keep turning for that. the trade off is losing the ability to coast freely.
but there ia a smart fix for that which is purely software in the controller : enable Regen when you slightly engage the brake lever, but if you wanna keep the ability to coast, tune the controller to provide just a tiny current to overcome the motor's drag. the ultimate addition is Regen control using the brake lever.unfortunately Regen is overlooked in ebikes and there is no off the shelf brake lever that would provide a position sensor for the regen or throttle working both ways but you could use a throttle just for Regen.
grin tech makes gmac geared hub motor without clutch that does regen. they also have a lot of very detailed/technical videos, including a 47min one about Regen. most would apply to a middrive with freewheel at the crank level:

 

[Mabman]

I use that exact same system from Grin on my drop bar eBike except I activate the regen via a momentary button switch attached to the left brake hood. Whenever I want to slow down it is the first thing I reach for because it acts like a brake drag basically. When bombing downhill at 30+mph with gravity doing it's thing it is often the only braking force I need but if I need more the brakes are easily at hand.

But other than that the amount of energy it puts back into the battery over the course of a battery cycle of around 30-40 miles depending on the terrain I am riding with a 500wh battery it might provide me with at most another mile of distance if the ride was in hilly terrain. However it does save on disc pad life and for the type of riding I do with that bike I would miss it if it wasn't enabled.

I don't see regen happening for the eMTB market anytime soon if ever but for road/gravel bikes I wouldn't spec one any other way.

 

[geemy]

I wonder what the trouble is with the Revonte? Is it investments, sabotage, or does it just suck? It should have been here by now.

one possibility is the tech is not refined enough for production. this will be expensive/low production so people don't want to pay big money for an ebike with weird pedal assist feel or transmission the other is that it's not easy to innovate and be cost effective against Shimano/SRAM. if the technology is so great, it will eventually find it's way to mainstream but it could take years. Shimano also has various internal gearbox patents under it's belt(although quite different from ecvt) they can wait and see, make the most money from current generation of 1x / electronic/wireless shifting, see the long term reliability/issues and sample the acceptance of the technology from early adopters, keep lobbying/pressurize big bike manufacturers to boycott this kind of tech, maybe wait for the company to go bankrupt and buy the patents on the cheap, before partnering with specialized/trek to make flagship ebike frames compatible with it.
could be 10 years before you see it on. more mainstream bike. Just look at pinion gearbox which is a good technical solution but lacks mass production/ compatible frames. Hopefully the growth of ebike market could make things happen more quickly

 

[geemy]

I use that exact same system from Grin on my drop bar eBike except I activate the regen via a momentary button switch attached to the left brake hood. Whenever I want to slow down it is the first thing I reach for because it acts like a brake drag basically. When bombing downhill at 30+mph with gravity doing it's thing it is often the only braking force I need but if I need more the brakes are easily at hand.

But other than that the amount of energy it puts back into the battery over the course of a battery cycle of around 30-40 miles depending on the terrain I am riding with a 500wh battery it might provide me with at most another mile of distance if the ride was in hilly terrain. However it does save on disc pad life and for the type of riding I do with that bike I would miss it if it wasn't enabled.

I don't see regen happening for the eMTB market anytime soon if ever but for road/gravel bikes I wouldn't spec one any other way.

cool
. what current/power are you using for Regen? I understand GMAC motor and phaserunner controller are able to generate huge amount of Regen, especially if you have good cooling, I mean "locking" the rear wheel kind of Regen but without a way to precisely modulate Regen (maybe even a kind of software abs) you cant apply full power Regen.
granted it's only on the rear wheel, so there's limited traction, I'd like to see something similar to my fiat 500e blended braking. braking with the lever, triggering Regen that you can modulate using the initial travel of your lever, then hydraulic brake seamlessly starting to kick in. I know it would be way too complex/expensive/heavy to be integrated in a bike brake lever and provide a good braking feel
I know it all depends on the type of ride, but grin tech reports 10% increase in hilly urban conditions with traffic lights, 15% with loaded cargo ebikes , and brake pads savings more than offsetting the battery degradation/replacement cost over its lifetime....provided you have a significant amount of downhill where you need to/can activate Regen, i you should be able to get more than 1 mile/2-3%

 

[RustyIron]

You will never see regeneration on an eMTB.
That Grin Tech boy seems to do a lot of talking, but not a lot of doing.

 

[Mabman]

Justin is the man in my book. I have met him numerous times and he is about as humble and gracious a person as I have ever met. He has been involved with e assist for years and built his business based on furthering knowledge of the possibility of e assist and walking the walk, or should I say riding e. Like Vancouver to California and back, across Canada and the Sun Race across the EU into Asia. Granted little to do with eMTB but there are other factors of using e assist in the world and hub motor bikes actually outnumber mid drives worldwide by a substantial margin and that has always been Grin's main focus.

And @geemy I use a stock Grin spec controller and the same motor in the above pic which is a front hub only direct drive of their design that is setup for toolless removal. The amount of regen is set fairly low because I don't want it to come on strong and prefer to use it as a drag brake. Regen on a bicycle, given it is many times lighter than a car, will never be as effective or efficient. Mass is an important part of the equation.

I know they have the GMAC now and it is a well thought out bit of kit but I would never switch to it over the simplicity of the front hub drive that I get two wheel drive out of also. I also use no PAS but can set, with a throttle that falls easily to thumb mounted on the right brake hood similar to the button switch, at any amount of watts I need like a cruise control which for road use works just fine and I am able to pedal at whatever cadence and pressure I want without drivetrain motor interference for as natural a pedal feel as one would expect from riding a bike.

But for my eMTB I ride a heavyweight/highpower torque sensing monster with gobs of suspension and low psi tires for maximum traction. Oh, and big disc brakes for slowing down.

 

[RebornRider]

I heard a comment in a recent GMBN video that nicely summarizes my take on CVT. I can't remember ever thinking that I needed another gear between any two that I have now. I have thought about converting from 11 to 12 sprockets along with a 36 tooth chaniring so I could keep my current granny gear and also be able to pedal on the steeper tarmac downhills. I can't get much beyond 120 rpm, and that is just a bit over 30 mph with my current setup. My regular ride includes a tarmac downhill (with a bike lane) that would support more speed if I could make my feet go around faster. I end up just coasting, but that feels so lazy!