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A comment on Chainless electric drive system “Free Drive” for bicycles (2021). Parent comment

Re:Chainless electric drive system “Free Drive” for bicycles... by olyjohn on Friday May 13, 2022 @01:15PM (#31370230)
Do you regularly run out of power on your chain powered bike though? I get the feeling this system requires a battery (it even mentions battery in the article), and most of the actual power comes from that. The question is, will the generator make enough power to get you moving if the battery is totally flat? I kinda feel like no, you'd have to sit there and pedal it just to charge it up, and then it would move you a few feet. Or you're going to be pedaling really fast, and moving nowhere.
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Re:Chainless electric drive system “Free Drive” for bicycles... by bryanlarsen on Friday May 13, 2022 @04:05PM (#31371991)
They claim to be 5% less efficient than a chain. So with a dead battery, you'd be limited to a speed of 95% of what you could do on a normal bicycle. That's if you're already moving. If you were at a dead stop I imagine you'd need to pedal a few strokes to get enough charge to get enough torque to overcome the stiction.
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Re:Chainless electric drive system “Free Drive” for bicycles... by tln on Friday May 13, 2022 @06:49PM (#31373330)
Where do they claim that efficiency? I'm pretty skeptical... Chain+Derailleurs can be 98% efficient IIRC
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Re:Chainless electric drive system “Free Drive” for bicycles... by radu_floricica on Friday May 13, 2022 @11:09PM (#31374768)
Electric motors/generators are in the same range. Also I doubt they need to target the best possible chain bikes in order to be a viable solution.

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.

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Re:Chainless electric drive system “Free Drive” for bicycles... by bryanlarsen on Saturday May 14, 2022 @12:36AM (#31375111)
I googled Schaeffer Free Drive efficiency.

A Tesla motor is 98.5% efficient, so a generator and motor combo being 93% efficient does not sound like a stretch.

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