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DrivEn drivetrain
 

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Pat Clancy
Joined: 13 Jan 2004
Posts: 1353
Location: Manchester, CT

7/11/18 6:59 AM

DrivEn drivetrain

Unlikely to ever be commercialized, but interesting.

https://newatlas.com/ceramicspeed-driven-shaft-drive/55364/https://newatlas.com/ceramicspeed-driven-shaft-drive/55364/

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Sparky
Joined: 08 Dec 2003
Posts: 19068
Location: PDX

7/11/18 9:14 AM

Seems so few drive contact points would wear fast...

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April
Joined: 13 Dec 2003
Posts: 6593
Location: Westchester/NYC

7/11/18 4:05 PM

But ceramics don’t wear out.

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Sparky
Joined: 08 Dec 2003
Posts: 19068
Location: PDX

7/11/18 5:26 PM

The ceramics are the shaft bearings, not the drive engagement mechanism from what I read.

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Brian Nystrom
Joined: 26 Jan 2004
Posts: 5096
Location: Nashua, NH

7/12/18 5:45 AM

The main problems with it are:

1 - The bearings are open, which means they're quickly get contaminated with dirt and the 1% increase in efficiency will go out the window. If you put seals on the bearings, the 1% increase in efficiency will go out the window.

2 - The flat driven disk will flex under any significant torque, which means that most of the "gears" toward the outside will skip as it flexes under pressure.

3 - The tiny fingers on the drive and driven disks will bend and break easily.

4 - They haven't figured out how to shift it and it may not even be possible to do so.

This is an interesting engineering exercise with no practical applications in the real world, with the possible exception of track bikes and other single speeds. At least it's a pretty neat example of out-of-the-box thinking...


Last edited by Brian Nystrom on 7/15/18 1:01 PM; edited 1 time in total

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daddy-o
Joined: 12 Apr 2004
Posts: 3307
Location: Springfield

7/12/18 7:09 AM

Building on Brian's assessment:

The weak link is the lack of engagement, crank or cog. It's designed to slip. The force transfer surfaces are riding on balls. This thing will never pass the Wayne Lim test.

They need to slap it on a single speed and have the local talent try to strip it. I'm betting if it hits prime time it will look more like a bevel gear than this over complex design school darling.

And just use a metal shaft until you get the engineering done.

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Brian Nystrom
Joined: 26 Jan 2004
Posts: 5096
Location: Nashua, NH

7/13/18 7:30 AM

Bevel gears would reduce the efficiency to way below that of a chain, rendering the whole exercise pointless.

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daddy-o
Joined: 12 Apr 2004
Posts: 3307
Location: Springfield

7/13/18 8:11 AM

Yep, and because of the flexing like you pointed out it probably wouldn't be any more reliable either.

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Brian Nystrom
Joined: 26 Jan 2004
Posts: 5096
Location: Nashua, NH

7/13/18 2:20 PM

There are - and have been in the past - gear driven bikes available that were reliable, but they trade efficiency for simplicity and reduced maintenance. AFAIK, they've all been single speeds, unless perhaps some used internal hub gearing too, which would drop their efficiency even more.

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daddy-o
Joined: 12 Apr 2004
Posts: 3307
Location: Springfield

7/16/18 5:04 AM

4:34 Video clip of the drive train on the floor of the bike show. See and hear it with commentary that reflects this thread.

https://www.youtube.com/watch?v=rgo-yEaXDzA

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Brian Nystrom
Joined: 26 Jan 2004
Posts: 5096
Location: Nashua, NH

7/16/18 5:48 AM

The noise and the apparent slop in the system are not impressive and don't bode well for its future.

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