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I cannot see why anyone would prefer this for a bicycle that is at all shaped like a normal bike. An integrated mid-drive ebike is just all around much more eff

I cannot see why anyone would prefer this for a bicycle that is at all shaped like a normal bike. An integrated mid-drive ebike is just all around much more efficient. 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.

kazinator 4y ago
> I cannot see why anyone would prefer this for a bicycle that is at all shaped like a normal bike. 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.
- mauvehaus 4y ago
  You make some good points, and I'd venture to guess that you're handy with a bike, but for the vast majority of people who use bikes, what you're saying about maintenance is totally irrelevant. 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.

kazinator 4y ago

> I cannot see why anyone would prefer this for a bicycle that is at all shaped like a normal bike. 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.

mauvehaus 4y ago
You make some good points, and I'd venture to guess that you're handy with a bike, but for the vast majority of people who use bikes, what you're saying about maintenance is totally irrelevant. 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.