14 ms·

I wonder how good they can make the feel without a direct connection to the road? For example, as you stand on a bike stopped at an intersection you have your

I wonder how good they can make the feel without a direct connection to the road? 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.

bryanlarsen 4y ago
A chain is 95% efficient in theory, but in practice they are usually a lot less.
- sudosysgen 4y ago
  In theory a chain can be up to 99% efficient. In practice, a clean modern chain can easily hit 95%. Chains are by far the most efficient drivetrain.
  - asdff 4y ago
    How do belt drives stack up? I see more ebikes going belt drive which makes me think theres some efficiency gain there or at least its able to handle more torque perhaps.
    - bryanlarsen 4y ago
      Belt drives are less efficient than a well maintained chain but more efficient than a poorly maintained chain. E-bikes are less concerned about maximal efficiency and more concerned about ease of use. Belt drives don't need cleaning and greasing like chains do.
    - masklinn 4y ago
      ebikes go belt drive for ease of maintenance and replacement, not for efficiency (they care much less since the motor compensates). 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.
makeitdouble 4y ago
> Regarding efficiency 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)
- aww_dang 4y ago
  Extra weight from the batteries and electronics could be a bigger efficiency issue. Durability would be my bigger concern. Perhaps this would be a good fit for something like an electrified velomobile.
  - sudosysgen 4y ago
    I think it could in theory be more reliable and require less maintenance than a traditional drivetrain, but it's definitely going to be 7-10% less efficient than a good chain system.
- hgomersall 4y ago
  People merrily put up with inefficient bikes for all sorts of reasons. If the only objective was to get between two points with minimal energy expenditure, everyone would be riding road bikes. Clearly other factors come into play.
  - jasonwatkinspdx 4y ago
    I have a track bike that's light as a feather, a cyclocross bike rigged with single rear derailed that's barely heavier, and a dutch style city bike that weighs like 4x the track bike. Guess which one gets ridden the most?
analog31 4y ago
It's interesting that after 140 years, the behavior of a chain drive safety bicycle with pneumatic tires is still the gold standard. Virtually everything that's noticeably better on my bike is related to the materials used. Although, variable speed gearing was a nice invention, but still, 100+ years old.
- sudosysgen 4y ago
  Indeed, the chain+derailleur system is incredibly lightweight, efficient, simple, and also fairly reliable. It's one of the most elegant solutions in mechanical engineering, imo.
  - aidenn0 4y ago
    I find the chain+derailleur system to be less reliable than drive-shafts, but it's trivially repairable for a 10 year old with no tools, which is a huge win.
  - brnaftr361 4y ago
    I disagree, I find chain and derailleurs to be annoying and unreliable in the worst way. I'll grant them their crown of efficiency, but I hope to see more refined CVTs. I currently have a bike with a NuVinci and I strongly prefer the way it functions over the clunky must-be-pedalling shifts of a derailleur. As an added benefit the system is contained, presumably hardening it against damage and reducing maintenance.
    - potta_coffee 4y ago
      I have 30 year old derailleurs with thousands of miles on them that are still going strong. I don't really understand the reliability complaint here.
    - asdff 4y ago
      How do you find it unreliable? I put a couple thousand miles on mine a year and it sits outside. Occasionally it gets hit with wd40 then lube and a rag. That's all I do with this thing. I don't get all the complaints from people on the fiddling with derailleurs. I've never had to fiddle despite years of riding. Just some shimano components mostly 105 and ultegra but nothing special or too new. I'm still riding 2x8 actually. Maybe the fewer rear gears leads to fewer issues with alignment? I do find that I can shift into any of the rear cogs easily with either front cogs, very permissive groupset to being in the wrong gear at the wrong time too and sloppily finding another one (a lot of chaos sharing the road). Maybe I'm just not attuned enough to feel when the gearing is going out though.
SigmundA 4y ago
>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). 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).
- skykooler 4y ago
  > There are no production series hybrids I am of aware of in automobiles Would not the Chevy Volt count? The gasoline engine only serves as a generator, it is not mechanically connected to the wheels.
  - wolrah 4y ago
    > 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.
- kevin_thibedeau 4y ago
  > There are no production series hybrids I am of aware of in automobiles The Chevy Volt was the first production series hybrid.
  - SigmundA 4y ago
    Volts have a mechanical connection: https://www.gm-volt.com/threads/gen-2-volt-transmission-operating-modes-explained.337644/ https://www.gm-volt.com/threads/gen-2-volt-transmission-oper...
Johnny555 4y ago
I don't think they are going for road feel: 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.
- tecleandor 4y ago
  > 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. 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.
  - Johnny555 4y ago
    Ok, then you start pedaling, but since they specifically say it provides constant resistance, it's safe to say that they are not emulating road feel.
    - MengerSponge 4y ago
      Having kick-started a bike uphill from many stop-signs, let me say that road feel is 100% overrated
  - stefs 4y ago
    i doubt it's designed for classic single-person e-bikes; there's one picture at the bottom of a cargo-bike with a person-sized transport box. i think this system is for small inner-city utility vehicles for delivery services and craftsmen (transport of a limited set of tools and material). 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.
wolverine876 4y ago
> 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. 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.

bryanlarsen 4y ago

A chain is 95% efficient in theory, but in practice they are usually a lot less.

sudosysgen 4y ago
In theory a chain can be up to 99% efficient. In practice, a clean modern chain can easily hit 95%. Chains are by far the most efficient drivetrain.
- asdff 4y ago
  How do belt drives stack up? I see more ebikes going belt drive which makes me think theres some efficiency gain there or at least its able to handle more torque perhaps.
  - bryanlarsen 4y ago
    Belt drives are less efficient than a well maintained chain but more efficient than a poorly maintained chain. E-bikes are less concerned about maximal efficiency and more concerned about ease of use. Belt drives don't need cleaning and greasing like chains do.
  - masklinn 4y ago
    ebikes go belt drive for ease of maintenance and replacement, not for efficiency (they care much less since the motor compensates). 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.

makeitdouble 4y ago

> Regarding efficiency 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)

aww_dang 4y ago
Extra weight from the batteries and electronics could be a bigger efficiency issue. Durability would be my bigger concern. Perhaps this would be a good fit for something like an electrified velomobile.
- sudosysgen 4y ago
  I think it could in theory be more reliable and require less maintenance than a traditional drivetrain, but it's definitely going to be 7-10% less efficient than a good chain system.
hgomersall 4y ago
People merrily put up with inefficient bikes for all sorts of reasons. If the only objective was to get between two points with minimal energy expenditure, everyone would be riding road bikes. Clearly other factors come into play.
- jasonwatkinspdx 4y ago
  I have a track bike that's light as a feather, a cyclocross bike rigged with single rear derailed that's barely heavier, and a dutch style city bike that weighs like 4x the track bike. Guess which one gets ridden the most?

analog31 4y ago

It's interesting that after 140 years, the behavior of a chain drive safety bicycle with pneumatic tires is still the gold standard. Virtually everything that's noticeably better on my bike is related to the materials used. Although, variable speed gearing was a nice invention, but still, 100+ years old.

sudosysgen 4y ago
Indeed, the chain+derailleur system is incredibly lightweight, efficient, simple, and also fairly reliable. It's one of the most elegant solutions in mechanical engineering, imo.
- aidenn0 4y ago
  I find the chain+derailleur system to be less reliable than drive-shafts, but it's trivially repairable for a 10 year old with no tools, which is a huge win.
- brnaftr361 4y ago
  I disagree, I find chain and derailleurs to be annoying and unreliable in the worst way. I'll grant them their crown of efficiency, but I hope to see more refined CVTs. I currently have a bike with a NuVinci and I strongly prefer the way it functions over the clunky must-be-pedalling shifts of a derailleur. As an added benefit the system is contained, presumably hardening it against damage and reducing maintenance.
  - potta_coffee 4y ago
    I have 30 year old derailleurs with thousands of miles on them that are still going strong. I don't really understand the reliability complaint here.
  - asdff 4y ago
    How do you find it unreliable? I put a couple thousand miles on mine a year and it sits outside. Occasionally it gets hit with wd40 then lube and a rag. That's all I do with this thing. I don't get all the complaints from people on the fiddling with derailleurs. I've never had to fiddle despite years of riding. Just some shimano components mostly 105 and ultegra but nothing special or too new. I'm still riding 2x8 actually. Maybe the fewer rear gears leads to fewer issues with alignment? I do find that I can shift into any of the rear cogs easily with either front cogs, very permissive groupset to being in the wrong gear at the wrong time too and sloppily finding another one (a lot of chaos sharing the road). Maybe I'm just not attuned enough to feel when the gearing is going out though.

SigmundA 4y ago

>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). 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).

skykooler 4y ago
> There are no production series hybrids I am of aware of in automobiles Would not the Chevy Volt count? The gasoline engine only serves as a generator, it is not mechanically connected to the wheels.
- wolrah 4y ago
  > 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.
kevin_thibedeau 4y ago
> There are no production series hybrids I am of aware of in automobiles The Chevy Volt was the first production series hybrid.
- SigmundA 4y ago
  Volts have a mechanical connection: https://www.gm-volt.com/threads/gen-2-volt-transmission-operating-modes-explained.337644/ https://www.gm-volt.com/threads/gen-2-volt-transmission-oper...

Johnny555 4y ago

I don't think they are going for road feel: 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.

tecleandor 4y ago
> 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. 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.
- Johnny555 4y ago
  Ok, then you start pedaling, but since they specifically say it provides constant resistance, it's safe to say that they are not emulating road feel.
  - MengerSponge 4y ago
    Having kick-started a bike uphill from many stop-signs, let me say that road feel is 100% overrated
- stefs 4y ago
  i doubt it's designed for classic single-person e-bikes; there's one picture at the bottom of a cargo-bike with a person-sized transport box. i think this system is for small inner-city utility vehicles for delivery services and craftsmen (transport of a limited set of tools and material). 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.

wolverine876 4y ago

> 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. 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.