Chainless electric drive system “Free Drive” for bicycles (2021)
schaeffler.de
schaeffler.de
For example, as you stand on a bike stopped at an intersection you have your foot resting on the petal, ready to take off. As you launch, you put a lot of force on that petal and rely on the feeling of connection to the ground to get going.
This motor is going to have to hold that force statically and have a control system with sufficient power and bandwidth to emulate the familiar feeling of the ground. Not impossible I guess, but I wonder how well it works.
Regarding efficiency, I think this is a smaller issue than it seems. Let's say a chain is 95% efficient and their system is 85% efficient (they claim 5% less efficient than a chain, apparently, but I'm sure that's a stretch). Most energy cycling, if not grinding up a steep hill, is dumped into air resistance. But speed only goes up with the cube root of power with regard to air resistance. This means (given the hypothetical numbers above) that you'd go 3.8% faster with a physical chain (or 1.7% if you believe their loss numbers). That difference is not perceptible on a bike and not an issue for 'getting around' use cases.
The elasticity of the belt could also be an advantage if the engine is at the pedals (rather than in the hub), as it would allow for a less smooth engine programming, using the belt’s elasticity to absorb some of the harshness.
Air resistance is the main factor only if you’re not actively stopping/restarting/braking as needed. In urban or semi-urban courses adjusting speed and stopping at red lights is par for the course.
Also efficiency is really about effort. 95% is low for a bike, but even taking a 10% difference compared to the chainless one: for the effort you’d put to ride 10km with a chain, you’ll only be around 9km chainless.
As you say it might not matter if you’re only going for groceries at 1 or 2km of your home. That’s a different story if you use it to commute or plan on longer trips (now it could be seen as a handicap to get more exercise depending on the target customer)
Durability would be my bigger concern.
Perhaps this would be a good fit for something like an electrified velomobile.
So, yes, people do care and want solutions to these trade-offs, and the current landscape already has decent answers to these concerns. IMO this chainless one would need to prove itself to be a lot better on some other dimension than pure maintenance.
Also I hate dropping gears in the middle of an intersection.
Maybe it's hopping curbs? Can't be helped here, the roads just aren't designed for bike commuting and everybody has a lifted 3/4 ton they can't fineagle into their garage. It's lovely.
Can't see how that would affect the shifting, but if you are graceless you can beat up the wheels enough to cause them to get out of true. If you have my wheelsets, 32 spoke 3x on HED Belgium Plus rims that I built myself, you can hop curbs all you like. I do, and I ride non-technical dirt too.
As for shifting, I've been riding for 45 years and have never had a problem with manual shifting, from the dark ages 5x2 speed to my current 9x3, 10x2 and 11x2 rides. Frankly I am happily shocked at the precision and durability of my newest bike, the 11x2, given the narrowness of the chain. After 2.5 years of 3x weekly 3000' climbing, including some dirt, riding through the winter, and the drive train is dirty, no missed shifts and no noise. Amazing. I would never have guessed that.
It should not be common for a chain to slip off, something is wrong. The something may just be parts quality.
Derailers are a case of getting what you pay for. The cheapest ones are junk and will never shift well. My partner bought a bottom quality bike with no-name shifters and it has never shifted correctly from day one. It does also drop the chain. No amount of aligning will get it to shift well.
In contrast my 18 years old mountain bike with Shimano XTR derailers has always shifted perfectly and still does.
Bike derailers is one area where it's definitely worth it to go for top of the line components and never worry about it again. Low quality components will make you hate they money you saved every single time you attempt to shift.
I do utility cycling and long distance tour cycling.
* Tension method of spoking: Invented by Eugene Meyer in Paris in 1869.
* Tangential spokes: If you look closely at bicycles, the spokes are tangential to the hub, not radial. The tangent-tension combination (and maybe tangential spokes independently) were patented by James Starley in 1874. The "spokes are placed so as to be tangential to the hub in both the forward and the backward direction, thus forming a series of triangles that brace the wheel against torque during either acceleration or braking." [0]
The improved spokes were introduced before chains and gears, allowing larger wheels. Larger wheels served as a subsitute for gearing, increasing the ratio between linear distance traveled and one rotation of a pedal, and thus the big-wheeled 'penny-farthing' or 'ordinary' bicycles were born.
However, knowing the history, I haven't yet grasped the mechanics of how tension and tangents benefitted wheels, beyond general concepts. Does anyone know a good technical source (not Wikipedia)?
[0] "Bicycle Technology" by SS Wilson (Stewart Wilson, afaik) in Scientific American (March 1973)
Band-drive systems with internal hubs are superior for commuters who need reliability over anything else.
Tubeless tires are now the standard for riding on irregular terrain.
Disc-brakes are not the standard for hilly areas or people who ride at high speeds.
Meanwhile, single chain-drive fixed/free gear bikes are still perfectly serviceable for most use cases (even if you need to select from a few different cog sizes to fit your area).
The reason why "chain drive and pneumatic tires are the gold standard" is that most people don't ride bikes. If people did, you'd see much, much more variation in technology on the street, as they would be used for functional purposes, rather than recreational purposes.
Off road cycling is its own beast, with the development of specialized bikes for that use, and also the design of trails that challenge both your skill and your technology. But the old footpath through the woods, or gravel road, is still the same as it ever was, and a regular bike handles it just fine.
In the US, there's a perpetual effort by the bike companies to get people out riding, when everybody's already got a nearly brand new bike hanging in the garage. They want to sell new bikes, so of course the silver bullet is new technology. I think the rapid adoption of e-bikes shows that the real barrier was not the detailed performance of particular components, but physical effort. Who knew?
Is there data on this rapid adoption? I'm not seeing it. It's hard to believe riding a bike is so much effort, but who knows?
In a lot of cases I think it might be less about effort itself, and more about climate and what the level of effort means in that context. I know where I live half the year the average temperature is 80F or above, and pedaling or not could very well be the difference of showing up as a sweaty mess that needs a shower on site to appear presentable or not.
Both enclosed chain cases and internal hub gears have been around over 100yrs though, almost from the beginning of bicycles.
Surprised it took so long for tubeless tires and disc brakes to become popular on bicycles since they've been used on motorcycles and cars for many decades. Otherwise the "gold standard" fancy bikes still exist and still look closer to a bike from 1900 than most bikes on shelf do.
[0]https://www.sheldonbrown.com/gloss_ba-n.html#belt [1]https://www.sheldonbrown.com/gloss_g.html#gearcase
Would be interesting to see proof of their efficiency claims, having looked into this before series hybrid drivetrains are in the 80% efficiency range, you have generator->charge controller->motor controller->motor losses.
There are no production series hybrids I am of aware of in automobiles, all hybrid seem to have a parallel component connecting engine to wheels at highways speeds because its much more efficient.
Trains and large boats do diesel electric drivetrains but its not for running efficiency but other factors like traction /throttle control and power routing.
Its very difficult to out perform a mechanical drivetrain in both weight and efficiency if your power source is mechanical (ICE / human body).
Would not the Chevy Volt count? The gasoline engine only serves as a generator, it is not mechanically connected to the wheels.
The Volt can operate in a series hybrid mode, but there is also a mechanical connection that is engaged at certain speeds where it's more efficient to just direct drive rather than double-convert the energy from the combustion engine.
The Chevy Volt was the first production series hybrid.
Nissan e-power cars are hybrids that you can't plug in, but all power is generated by the ICE and then fed to the electric motor before it gets to the wheels.
The Nissan e-power is interesting, having not dug deep into it before, it looked like it obviously had a engine to wheel connection through the transfer case. Thought they where pulling a Chevy and claiming series hybrid when actually parallel, but just digging deeper its very strange the engine output and drive gear are separated only by MM as though they where leaving the design open to a mechanical connection. Never the less its difficult to get highway MPG numbers on it which is why most hybrids have a mechanical connection. Electric is more efficient stop and go city driving while steady state highway mechanical transfer is more efficient. Would like to see power loss numbers and highway mpg, my guess is on the highway the E-Power would lose out to a Prius.
https://www.greencarreports.com/news/1105823_bmw-i3-rex-rang...
And again my main point was on efficiency, I would hope you agree 31mpg combined is extremely poor for a 34hp engine when much larger engines get much better mileage and have no issues with providing power when needed without battery assistance.
It doesn't need much hp to maintain highway speed (probably around 34hp on flat ground) which means the engine is running full throttle to do so, vs running in it most efficient range which is not where it puts out peak power.
The e-power Nissan has a full size engine, but a small battery, although would be interesting to compare it drivetrains weight with a standard one, having both a electric motor and generator of equal size is typically much heavier than a transmission.
My commute is very stop-go, otherwise I think the car would be in the upper-60s all the time. I've often wondered if there was a way to have an electric motor handle the movement of the car up to about 15 mph.
What it's not enough for is much acceleration at those speeds. But a battery buffer would help hugely, as long as you aren't driving very sportily for an extended period of time.
In theory a hydraulic pump would work, but I'm sure that electric motors are better for that usage, since that is what they use.
By virtue of being the dominant automatic transmission in the US, where automatic transmission is the overwhelming majority.
In Europe, torque converters have never been much of a thing, historically because of the small engines (at the low end, and demand for control and responsiveness at the high end), and more recently for efficiency reasons.
AT has been shooting up in popularity (in parts because gearings have been getting shorter which makes manual transmissions really annoying), but mostly on the back of DCTs, even at the low end e.g. these days it's pretty common to find a 6-speed DCT on a B-segment car, and C-segments getting 7 or 8-speed DCTs (AMTs sadly still survive at the lower end of AT, but I feel CVTs are eating their bacon, especially with progressive hybridation).
https://www.autocar.co.uk/car-news/technology-news/under-ski...
https://www.caranddriver.com/features/a23367341/automatic-tr...
The small-engine problem was basically just another aspect of the efficiency problem: Torque converters used to be so inefficient that if you had very little power to begin with, close to none at all got through to the drive wheels.
Except those that actually use hydraulic couplings or torque converters, which is the cheaper and lighter solution compared to electric, albeit less efficient.
The central component of the Free Drive system is the Schaeffler generator, which sets the constant resistance on the pedal while simultaneously absorbing the rider's pedaling power
So I think with this bike when you take off from a stop, you just squeeze the throttle or whatever controller it has and take off using battery power.
On the other hand, you can pedal at your most efficient cadence/force all day long without regard to terrain.
As they are German, I think that's not the case (if they want to be classified as an eBike). To be classified as an eBike it needs to work in "pedal assistance" mode. That is, you can't have a throttle/button/whatever, the engine only starts if you are pedaling.
the low overhead of bikes (registration etc.) isn't necessarily a problem for a company's motor pool. iirc it might very well be possible to ride those on bike paths - even if they need a moped registration plate - as long as the maximum power and speed is limited.
in austria, small electric numberplate-less mopeds (scooters) with a 25km/h speed limit and no pedal assist are legal, no idea about germany tho.
I understand that consumers will demand it, but ignoring that - what if they didn't simulate that resistance? Is there a functional need for it? What would it feel like? It's hard to imagine.
https://www.theverge.com/2021/9/2/22653697/schaeffler-free-d...
It's got "barstools" along both sides and the passengers/revelers are supposed to turn the pedals under their seats while the bartender/driver steers.
In reality, the pedaling charges the battery somewhat but the vast majority of the battery power comes from being plugged in at a charger before the ride. You can't actually rely on a bunch of drunk sods to keep it moving.
So, like, no nudging the right handlebar forward to turn right? Bummer!
That capability is much more important than the efficiency loss of the generator/motor powertrain.
Such capability is not necessary on a bicycle, where efficiency is extremely important.
Because if something goes wrong with your phone you probably won't be able to fix it. Compared to a bike where most anything can be repaired.
I've had this system in mind for years, I think for cargo bikes with long chains, this will be a clear winner.
If you're riding a single speed bike and the chain regularly derails, then that definitely sounds like a chain tension or alignment problem.
Since it has a battery and the battery is (most likely) chargeable, a little loss of efficiency is inconsequential. On the other hand, having an actual physical chain on an electric bike seems indeed unnecessary - at least for less sporty applications, where things like "feel" or precise power delivery are not important. The end result will be a simpler, more reliable bike. Not to mention better looking.
A Tesla motor is 98.5% efficient, so a generator and motor combo being 93% efficient does not sound like a stretch.
2. If it's the rear derailleur, it may be bent (especially if your limit screws from step 1 are maxed out). You need a derailleur alignment gauge (or just take it to a shop) to verify.
Be careful when you do this so as to not apply too much power when you're trying to do this. If you're in a really high gear and it happens, you can get off, hold your rear tire off the ground and turn the pedals. Works 90% of the time unless you got your rear chain jammed between the cassette and the spoke.
Edit: You can very often see this if you watch professional bike racing. When the mechanics change a rear tire it will almost always knock the chain off of the front chainring. They'll just shift into the proper direct (low if it's off the high side and high if it's off the low side) and then spin the cranks and the chain will come back on.
You get the idea. At the leading edge, bicycles are already extremely complicated. If we're comparing this idea to a bicycle from 2002, it's complicated. But I'm not sure that it's that complicated compared to the kind of bike you'd find in the roof rack of an Audi S4 Wagon :-)
A high-end regular-bike has electronic shifting and a power meter and that's about it. And you're talking many thousands of dollars worth of road bike. It's like seeing a Ferrari or a Lambo rolling down city streets. They exist but they're rare.
I think it's reasonable to compare a leading edge technology to a leading-edge existing product. Otherwise, it's like it's 2007 and we're complaining that this newfangled iPhone thngie can run out of battery in a day, while my POTS telephone works even in a blackout.
Yes, true, but apples, oranges.
You can expect to change the chain every 5000km. In theory a fully electric drivetrain could last forever.
Which often have most of that and a chain too.
But also, e-bikes can let you ditch gears, which add complication.
But I think the main selling point is that you can seperate the sitting/cycling position from the driven wheel in interesting ways.
This is literally just get on and start pedaling and the bike figures out the rest. It even makes e-bike controls super easy, since you can just set a speed and start pedaling and it will supply just enough juice to make up the difference.
The obvious downside is that it's going to be less efficient than a chain drive, because nothing beats a chain drive. But if you basically get the benefits of an e-bike for free then the efficiency loss isn't a big deal for the rider.
It has a single gear, you can spin the pedals backwards to engage full regen, but the secret is that its usually doing a little regen which it stores and uses to help on hills and when accelerating from a standstill.
Maybe in other areas people are doing 60kph on bike trails or something, but that's not what I see around me. They seem to top out around 20kph or so, which makes them basically just bikes as far as traffic flow is concerned. Sure they will zoom past you on the uphills, but who cares? It's not hurting me or anybody else.
They must not have sold very many of them because Fallbrook-NuVinci went into chapeter 11 and enviolo bought the tech.
I think 'niche market' is an underestimation, since there are already assisted racing/MTB bikes (limited to 28km/h), just slap power meter pedals on and you're ready to go.
When I was younger, the machismo of winter/rain commuting was a fun brag at parties. Now, when I look out the window after a long day at work. I want my exercise miles minus the macho.
This could help me get that winter bike.
It's also a lot of sail surface.
Adding batteries, more waste and breaking points is now "environmentally friendly" because "electricity"
Replacing a ICE scooter is an electric bike is positive, replacing a regular bike with an electric one is a net negative. The argument only works if it replaces a more polluting option. Just like a Tesla can be a net negative depending on what it replaces
The carbon cost of a joule of food is higher than a joule of electricity, and joules are what get you where you're going.
You can make a case that it's nice exercise you needed anyway; I like bikes as well. But the claim you're making isn't obviously correct and I would say it's more false than true.
Like what is your point? That we aren't on a path to a perfect society? Do you think complaining is going to change that?
When going downhill, you are going faster thanks to gravity. A small increase in speed requires a disproportionally large increase in effort. Hand-waving over the inefficiencies involved in an electric power train, you are far better off pedalling and storing the energy on the downhill, then "spending" that stored energy on the flats or even saving it for the next uphill.
With respect to going downhill faster with this system, I doubt it can do anything useful in a straight line descent, but in a long, switchback descent of the type seen in the big Grand Tour races on mountain stages, cyclists need to brake into the switchbacks and accelerate out of them.
Regenerative braking followed by assisted pedalling out of the corners would be a huge win.
...Until the next ascent, where you have to haul the weight of the battery and what amounts to two electric motors uphill...
Although it seems sacrilegious to imagine energy-recovery units in UCI bicycle racing, innovation is strongly influenced by the big manufacturers who are trying to sell bikes.
It's unlikely there will be a UCI-sanctioned ERU any time soon, but if there was, the key to adoption would probably be the UCI minimum weight regulations. We are now at the point where high-end bikes often need weights added to meet the minimum, and if the rest of the bike ever gets light enough, it could be possible to add an ERU without compromising the total weight for climbing.
But that would require breakthroughs in the culture of bicycle racing and multiple technologies.
-- Are you much of a biker? (I put on around ~1,000 miles a month on a 29" mtn bike.
Knobby tires and all.
At no point ever have I worried about wind resistance - and im not a "shave my legs tour de france" (my brother is, but hes an ultra athelete-type-A Doctor) type that worries about my grams per component, corporate spandex or $12,000 week-end ride.
So, while you may be "technically correct" you're commenting as "functionally illiterate"
https://www.bbc.com/sport/cycling/36142963
If you don't want to cheat with a motor, bicycle stores sell all kinds of road bikes with pedal assist for non-competitive riding. Trek, for example, make several e-assist versions of their Domane road bikes:
Wind resistance absolutely matters in every discipline of cycling, and you don't need to have been fooling around with bikes for forty years to know that. If it didn't matter, what are all those triathletes and time trialists doing with aero bars, flat backs, and disc wheels?
It matters in MTB as well. The optimal position for efficiently generating power on a bicycle is actually quite upright, you can see this if you look at pictures of people riding "roller races," they usually flipped their handlebars up so they could be much more upright than when riding on a track.
XC MTBs have much lower bars than would be most efficient on rollers without wind resistance, and that's because the lower position generates less drag, knobby tires and all.
Even if you aren't riding a time trial or racing XC on an MTB, knowing where to expend your energy and where to save it matters greatly. If your daily commute involves hills, you will work less and arrive sooner if you don't try to crank your max while descending, and save your efforts for climbing.
That's just math and physics.
---
Also, please, I'm not upset at any random internet person using insulting language, but it is not constructive for our community to go around suggesting other users are "functionally illiterate."
LOVELY
and thank you for the response, proving your functional literacy :-)
AWESOME.
Anyway, when you close with just "Math/Physics"
Its a great comment, I just dont, on my personal, take ANY of that into account, as I am there for the ride and not to best anything.
But I LOVE everything about what you said and do.
I need to know you
But it’s still not cycling. For that you have to throw a leg over the top tube and go out and suffer, and fall, and get up, and bend a bent hanger back to fix it after the fall.
And ride, and ride, and ride. And wear a shit-eating grin so hard that your face hurts, but you can’t stop grinning in the wind, because riding feels so damn good.
If you ride, that’s all I need to know. See you on a trail someday, maybe.
What I would love to see though would be this, applied to a recumbent or a velomobile. Those often have atypically long chains.
Regen braking makes much less sense on bikes because bikes are weight-sensitive.
https://gocarlite.com/electric-bicycle-regenerative-braking/
> The way regenerative braking is implemented is to have the motor continuously engaged.
This is wrong. Regen braking only requires the motor be engaged _when braking_. There's no reason you can't coast when you want to coast.
Do keep in mind, a direct drive is always "engaged" to some extent by the cogging force. An advanced controller can make a direct drives "freewheel", but it actually takes power to do that. Totally worth budgeting for a slightly larger battery to allow a simpler overall design.
Now if you say, had a mid-drive bike, or an internally geared hub, there are some complicated mechanical systems you can put in place to lock the freewheeling mechanisms in the gearing when you want to apply the brakes, but I haven't seen anyone design that yet.
Mid-drive bicycles are able to leverage the freewheel, and thus have very high coasting efficiency.
You don't really seem to know much about this. It's odd that you seem to have formed strong opinions on said subject.
There is fierce competition in the industry for efficiency/range/price...not really sure why you think you can just casually stroll in and go "well DUH, folks, just do..."
Something which is rarely done but easily could be for a bike is regenerating first into a couple supercapacitors, which are 99% efficient and fill and discharge as fast as you can push current. They don't have the capacity to be as useful in cars, for a bike they can also provide a nice kick to overcome starting torque. The downside is it's another two drink can's worth of volume to add somewhere on the bike.
This is a niche in a niche though.
Later Specialized bikes have a regen mode you can engage manually but it's still basically never worth it.
For an electric bicycle though, I see it as a really good contender
You pedal to generate energy, and move that energy to the wheel through wire and another motor. (I'm not saying this is a good idea, just describing what I understood).
I'm curious what sort of efficiency you can expect on a ridiculous system like that.
I was referring to different types of gears and power transfer like driveshafts or hydraulics [1], if you can make it perform at a consistent 90% efficiency it might beat chain drive in practice even though it shouldn't in theory.
Also, many, many transportation bicycles have chain cases, which is much simpler than a motor-generator system.
There are bicycles with chains, belt drives, pedal assist electric, and throttle electric. I would be interested to know if this system could work without plugging in, get me up a steep climb, and do it cheaply. I use chain drives but belt seems to be the winner at the moment.
Don't remember where I read it, but e-bikes are becoming prevalent enough in some parts of Europe, that there is a bit of a regulatory backlash going on, for instance requiring a bike to get at least 1/2 of its power from the rider.
The difference is that now the motor is electric, not a small petrol engine. Will be interesting to see if we end up treating them (again) as small motorbikes, or as bikes with assist (so no compulsory helmet, insurance, or registration).
Edit: around here (Liverpool) I see them styled both ways. Some look like motor scooters with pedals, others pedal bikes with a motor. Seems to be fashion rather than functionality that determines which.
The Honda Spree, with electric starter and centrifugal clutch, put an end to mopeds.
Actually, most of the e-cyclists are quite well behaved, but there does seem to be a tendency among the beginners to maneuver through things at speed, that a conventional cyclist would slow down for. My guess is they haven't developed a sense for how far ahead of themselves they actually need to be paying attention.
But also, I admit that there's a certain bias here. There are fast and slow cyclists, and those who are polite or jerks. You don't notice the polite cyclists at all. You don't notice the slow jerks, because they're behind you. You only notice the fast jerks, on either electric or conventional bikes. So there's a bias towards thinking that fast riders are jerks.
That is key. Brakes are largely unregulated on bicycles, at beyond laws saying that they need to have them. Standards for braking power and/or stopping distance would be fought tooth and nail. All those ultra-efficient bikes on slim tires wouldn't be possible if someone set minimum stopping distances.
The US CPSC does regulate bike brakes. The latest generation of e-bikes actually have quite effective brakes, nearly entirely hydraulic discs.
https://www.ecfr.gov/current/title-16/chapter-II/subchapter-...
There was a man in the UK recently charged with the death of a pedestrian. He was on a fixed-gear bike without front brakes. Causing death during illegal activity means homicide charges in many jurisdictions.
An escalator can never break: it can only become stairs. You
should never see an Escalator Temporarily Out Of Order sign,
just "Escalator Temporarily Stairs. Sorry for your convenience."
But I've also broken frames and taco'd wheels. Should I bring spares for those?
That generator can probably do a million miles.
Not sure why you're "trashing your gears" so regularly. Older cassettes/chains didn't like being shifted under significant power but anything made in the last 20+ years by SRAM or Shimano or Campagnolo really shouldn't have a problem being shifted while full-on sprinting.
As long as the drivetrain is set up well initially, a traditional bike will go many thousands of miles on pretty minimal maintenance.
"A series wound electric motor has infinite torque at stall"
Okay, the electric connection between the pedals and the drive wheel should act as essentially as a perfect transmission, that is, with infinitely many gears (except for the 5% or whatever is lost in efficiency). And if the wheel motor is "series wound", then should have the "infinite torque" when starting from a dead stop. That infinite torque could be nice to have when going up a steep hill -- e.g., for the last 10 speed bike I had, the lowest gear was still not low enough to let me pedal up my steep driveway and, instead, I had to walk my bicycle up that hill.
Also, for that bike, the highest gear was not high enough -- on the course I was using, there was a long hill, and in the highest gear before I got to the top I was pedaling as fast as I could and wanted a still higher gear.
Sooooo, for something better, if the constant torque generator had a resistance adjustment, then just increase the resistance a little, let me pedal at the same RPM as before, and get up the hill faster; that is, I would be pedaling with my maximum power and the infinite gearing would move the bike at the maximum speed for that power, e.g., the power needed for the friction and air resistance for that maximum speed.
Constant torque at the generator side and infinitely many gears connecting to the drive wheel -- NICE!
Direct hub motors for large (bike size) diameter wheels frankly suck at this point in time. You need to have much more copper to efficiently drive the motor at the power levels required, because RPM is so much lower with hub motors. Not being able to use RPM to your advantage is such a huge efficiency hog at low speed acceleration, which is a lot of how people use ebikes.
If this is using an internally geared hub, my point is moot; however that comes with it's own drawbacks. It's incredibly hard to get heat out of a geared hub motor efficiently. Your motor is encased inside the hub, with no direct connection for heat to escape, and you generally have way less copper available to heat soak.
Mid drives get the advantage of mechanical gearing, and can be built in such a way to allow very little heat generation to begin with, but you also can easily cool something in the frame compared to a spinning hub.
There are already e-bikes out there with a design that puts a motor into the bottom bracket; so there are already frames for this.
That's probably what is being targeted.
In the absence of such frame designs existing already, this idea would be hard to pitch. The path already seems paved though.
We have e-bikes with bottom bracket motors, which assist the pedals, and drive a chain. We also have bike wheel designs with a hub motor that can retrofit into ordinary bikes.
This looks like it just combines the two: take a bike which has a bottom bracket motor, and replace the motor with a pure generator. Scrap the chain and sprockets, and just deliver electricity to a hub motor.
Chains and sprockets get dirty and require cleaning, except in fully-closed systems that require a complicated transmission. Chains can slip and break. Chains wear out and require replacement, usually together with the rear sprockets. Front rings wear also; about once every three times you change a rear sprocket, you have to change the front rings which, for entry level bikes is usually most cheaply done by getting the entire crank set.
Typically, a multi-speed rear cassette must be removed in order to replace a broken spoke, which is a PITA. This is because it is larger than the hub, and is right next to it, blocking access to the spoke entry holes on the drive side. You need chain whip to prevent the hub from turning, while you apply a wrench to a special lock ring tool, using a great deal of force. From the looks of most wheel builds with a hub motor, it looks like the spokes are easily accessible without removing any difficult part from the wheel: just get the wheel out of the bike.
Internal gears alleviate some of the issues with chains. Without a derailleur system, chains can be encased to protect them from the elements. An electric transmission is going to be more efficient and quieter than internal gears, though, and require no maintenance.
I'm also handy with a bike, and I've spent some time volunteering fixing up used bikes for resale. Here's what I usually saw:
> Chains wear out and require replacement, usually together with the rear sprockets. Front rings wear also; about once every three times you change a rear sprocket, you have to change the front rings which, for entry level bikes is usually most cheaply done by getting the entire crank set.
This is true, but very, very few bikes ever get the kind of miles put on them to wear out a chain. If you ever wear out a chain, you're conservatively in the top 3% of cyclists by miles ridden. Mostly chains die a slow horrible death by being left outside all winter and turning entirely into a rusty immovable mess. If they're completely beyond saving, you cut them off with a hacksaw, put on a new one, check the cassette, and move in to the next neglected thing. I've never replaced a cassette other than on my own bike, no matter how nice or shabby the bike looked.
In the extraordinarily unlikely case that somebody manages to wear out the chain on a cheap bike, they're almost certainly as well off just buying a new cheap bike. Everything on a cheap bike is crap, and by the time you've killed a chain, something else will need to be fixed. Unless the labor is free (mine was, that was the point), you're quickly into more money to polish a turd than to buy a new one.
If by "entry level", you mean "inexpensive from an actual bike shop", then yeah, it might be worth replacing some drivetrain components. Even so, you'd be dealing with the unicorn rider who rides enough to wear out a chain, but also doesn't want to upgrade to a midrange bike.
> Typically, a multi-speed rear cassette must be removed in order to replace a broken spoke, which is a PITA. This is because it is larger than the hub, and is right next to it, blocking access to the spoke entry holes on the drive side. You need chain whip to prevent the hub from turning...
I've broken and replaced spokes. It's pretty rare, and it requires special tools. Most cyclists can't adjust a derailleur, and a surprisingly large number are incapable of fixing a flat.
Everything you're saying is true, but for nearly everybody, a broken spoke is a job for a bike shop. The barrier for replacing a spoke for most people isn't having the tools, it's knowing how to use them, and specifically how to re-true the wheel. I don't mean getting it perfect on a stand, I mean getting it rideable using the brake pads for a reference.
I know somebody who used to race competitively. He has a shop do all his maintenance because he's not even the slightest bit handy, and I can only assume it's not for the lack of opportunity to learn while he was riding competitively.
> This is true, but very, very few bikes ever get the kind of miles put on them to wear out a chain.
I suspect that is changing with e-bikes which are used for actual daily commuting. People buy those things to ride them.
In my experience, daily commuting of around 20 km on a non-powered ordinary bike all year round requires a yearly chain replacement. You can get away with a once per two years cassette job.
Now these e-bikes have serious torque and power. You regularly see them keeping up with cars going 50 km/h or more, even uphill. Yet may use use ordinary drive trains, such as entry-level Shimano cassettes, derailleurs and rings. The power of the motor can easily be expected to trash these components way faster than a human power.
> In the extraordinarily unlikely case that somebody manages to wear out the chain on a cheap bike, they're almost certainly as well off just buying a new cheap bike.
This is false, because chains cost something like $15-$30. Cheap chains and drive sets are still found on entry-level real bikes that might go for $600-$800 or whatever. You're not going to replace an $800 bike because of the chain.
It wouldn't make sense to replace even a $100 bike-shaped-object if all it needs is a $15 chain. There was a time when I rode crap bikes; I still maintained them, and replaced the chain.
> I've broken and replaced spokes. It's pretty rare.
During my daily cycling era when I didn't have a car for some 8 years, I fixed about 3 broken spokes per year. Almost always on the drive side of the rear wheel. So while rarer than a flat tire, it's not that rare.
I had no time for bike shops. They are too far away and have stupid hours like not opening until 10:30 on a weekday, and being closed Sundays. They will keep your bike for at least a day, and charge some ridiculous amount to change a part that costs a dollar.
Truing a wheel is not difficult (particularly lateral-only truing), and once you go to disc brakes, perfection is less important. The bike can even be ridden for a few days with a broken spoke: you just have to clip it off, because you don't want a broken spoke flailing around. It's not a great idea to ride a wheel with a broken spoke, but lets you schedule a good time to fix it, if you're busy
What I'd pay a shop to do would be axial truing: fixing the eccentricity of the wheel's circle. I asume that if I tell a shop to true a wheel, they are only going to care about left-right wobble, which "anyone" can do.
This hints at one less obvious advantage of the drive system described in the article: no need for asymmetrical wheel dishing. Rear wheels for conventional derailleur systems have to be built asymmetrically[0]. This makes the wheel weaker than a symmetrical one, because the drive side spokes are under higher tension.
I ride a hub gear bicycle with symmetrical wheels as my primary form of transport and I've never broken a spoke. Electric drive would allow the same wheel strength.
You also fall into one of the (as far as I can tell) two groups that skew heavily towards caring about end-user maintainability: hard-core transportation cyclists (you, and to a much lesser extent me), and people who bike tour (me as well, though not recently)
People are not going to fork up two thousand dollars just to have the thing sitting in storage; they are looking to it to solve a transportation problem.
Only the spoke-changing maintenance issue applies to hard-core DIY people; the remainder of the point is that the electric transmission likely requires next to zero maintenance. So for the non-DIY people who don't maintain bicycle drive trains themselves, this still means less downtime and expense.
If a spoke is easier to change, that could make a difference to your bike shop visit: "sure, I have some time to do that within the next one to two hours" versus "I can have that ready by noon tomorrow".
The e-bike people try too hard to pretend they're not building light-duty motorcycles. This seems to be changing. The wheels are getting smaller and stronger, and the center of gravity is going down.
Like others, it didn't at first make sense to me when thinking about efficiency losses and material complexity, but later realized it might have a place in certain battery-electric delivery bike applications where the majority of the power will be coming from a pre-charged battery. Think about how one could, in a worst off case, charge the bike pedaling in standsill position in a shaded area (while reading a book or using your phone) before trying to continue using the bike.
And between the limited maintenance and the ebike-engine, direct-drive efficiency also becomes less of a concern.
A quick googling led me to this statement about Germany and e-bikes:
"Insurance and license plates are required. The maximum motor output is 500 watts for e-bikes. Also, e-bike drivers must use bike lanes unless there are none, in which case they are allowed to ride on the roads."
From: https://adoebike.it/en/an-ultimate-guide-to-e-bike-laws-in-e...
In France, pedelecs (pedal-assist, assist is capped to 25km/h) are allowed on bike lanes, but speed bikes (not limited to 25km/h, they can reach the same speed as cars in cities, often 50km/h, and do not require pedaling) are not allowed on bike lanes.
For all intent and purpose, a speed bike (or however you call it) is an electric moped.
https://leva-eu.com/eu-commission-finally-confirms-series-hy...
https://downtown-mag.com/en/new-eu-regulation-declares-ebike...
Quote from the second article:
The EU Commission’s statement ends an almost 5-year problem that has unsettled and set back manufacturers investing in the development of series hybrid bicycles. Undoubtedly, this technology is still a niche product but manufacturers such as automotive supplier Schaeffler are increasingly investing in this technology.
I'd be more concerned about how a drive system like that would subtly fail to tickle the endorphine feedback loops the way a bike does. I don't think you'd notice on a conscious level, chances are you might even think you enjoy getting button-press acceleration from the battery buffer, but riding a bike has an immediacy that is close to the walking/running evolution has wired us for. I doubt that an e-scooter fueled by an ergometer generator would come anywhere close. I'm somewhat involved with a cycling vacation business and the way a day of being exposed to those feedback loops makes everybody involved happy that business feels almost like cheating. I really doubt that "ergometer driven e-scooter" could ever come anywhere close to that. But, well, Schaeffler isn't aiming at recreational cycling at all, just at the last mile delivery industry. I could not even guess wether it would make those jobs even more miserable or not.
Though interestingly it could also put a hard limit on upper speed, since "motor assistance" has to cutoff at 25km/h. A series hybrid bike might be considered to only work off of motor assistance (ignoring downhill).
How much efficiency is lost compared to a direct mechanical system?
wikipedia says up to 99%:
Mechanical efficiency
From a mechanical viewpoint, up to 99% of the energy delivered by the rider into the pedals is transmitted to the wheels (clean, lubricated new chain at 400 W), although the use of gearing mechanisms reduces this by 1–7% (clean, well-lubricated derailleurs), 4–12% (chain with 3-speed hubs), or 10–20% (shaft drive with 3-speed hubs). The higher efficiencies in each range are achieved at higher power levels and in direct drive (hub gears) or with large driven cogs (derailleurs).
These figures are quite less useless, you've to put them in perspective with the system weight (bike + rider), just can't escape physics.