Theoretically dream drivetrain

Discuss light weight issues concerning mountain bikes & parts.

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TheRookie
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Joined: Wed Jan 18, 2012 4:23 pm
Location: Midlands, United Kingdom

by TheRookie

mattr wrote:Get a half link every 31 links.

Then pray the chain doesn't come off

With a chain length in multiples of 31 only (so it will have to be 124 realistically) ... then a whacky mech to keep chain tension.....
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by Weenie


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DanW
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Joined: Fri May 02, 2008 5:39 pm
Location: Here, there and everywhere

by DanW

The correct answer to this thread is of course "XTR functionality and durability, hidden inside the frame and constantly lubed for totally maintenance free riding at a lower weight than anything out there at the moment". Shimano Di2 gearbox? :)

HaakonJohansen
Posts: 284
Joined: Mon Sep 01, 2014 4:58 pm

by HaakonJohansen

TheRookie wrote:Why not have a positive actuator on the front chainwheel to move it from the 'inner' to 'mid' to 'outer' chainline at a pre-determined shift point? Very easy if running electronic actuation.

Not sure how you make a narrow wide 31t though?

I was thinking about this myself, but wouldn't this bump the weight a bit? Another thought could be a chainring that floats on the spider, but I guess this wouldn't work very well. I guess there would be a lot of creaks and the system would probably be a lot weaker than a standard chainring.

HaakonJohansen
Posts: 284
Joined: Mon Sep 01, 2014 4:58 pm

by HaakonJohansen

Dirk wrote:Rear cassette with 14 gears, carbon spider carrier (reinforcement), machined steel dome (cfr XX1, but much slicker, after mating with the carbon spider, the cassette will achieve its ultimate strength.(9-48?)
Boost+ standard 155mm rear spacing.
Front: 1 floating 31t Narrow-wide chainring with carbon spider and steel teeth, to achieve optimum chain line according to the sprocket chosen on the rear. Say 55mm to 44mm?
F.e.: If you shift from the 9 teeth sprocket upwards to 48 teeth, the 11 sp-chain will exert a pulling force on the front chainring and thus move it to the optimum chainline and vice versa.
If the floating chainring is hinge-carried instead of moving on a kind of 'rail', it should be less prone to dirt.

This setup should save chain and cassette life.

Overlooked this when writing my last post.

Jan
Posts: 43
Joined: Wed Sep 15, 2004 8:50 pm
Location: Trondheim, Norway

by Jan

Dirk wrote:Front: floating chainring


http://www.google.com/patents/US20130008282

froze
Posts: 430
Joined: Thu Aug 05, 2010 3:47 am

by froze

SportingGoods wrote:actually, I would design something even more innovative. I would consider a continuous gear system (linear or not, but continuous). This would get rid of shifting completely.

PS: I guess you are also on the Chinertown forum :)


They have a CVT transmission for bikes but the current models are too heavy for either serious MTbing or road biking. I personally think if they can get the weight down to similar weight of what we currently use the CVT transmission would do away with not just mechanically shifted derailleurs but also electrically shifted. There may be other enhancements they may have to do with the CVT besides weight that I'm not aware of but that sounds the most promising to me. One of the enhancements I thought of was the ability to dial in your own personal max and min cadence, once you establish that the CVT would constantly keep you moving through the "gears" seamlessly as inclines, declines, wind, or whatever as the cadence hit the presets. This can all be done without ever shifting manually, so all shift cables would be gone, there would be no battery or servo motors or computer glitches to worry about, all you have to do is just ride and worry about stopping.

Stopping, ahh there's another subject, since we now have disk brakes they should immediately come out with anti lock brakes, because on dry pavement disk brakes vs rim brakes there is no stopping distance difference due to friction of the road vs the tire, but with anti lock brakes then you could seriously stop faster in all road conditions.

TheRookie
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Joined: Wed Jan 18, 2012 4:23 pm
Location: Midlands, United Kingdom

by TheRookie

CVT's have horrible transmission efficiency, that is what they are disappearing from cars to be replaced by multi speed (7+) conventional auto's.
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Chiva
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Joined: Sat Apr 03, 2010 11:05 pm

by Chiva

Wireles e-gripshift

mattr
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Location: The Grim North.

by mattr

Sounds like a nightmare......

Wingnut
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Joined: Sat Jun 23, 2007 12:41 am

by Wingnut

Dream drivetrain...Rohloff at a 1/3 of the weight...

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TheRookie
Posts: 926
Joined: Wed Jan 18, 2012 4:23 pm
Location: Midlands, United Kingdom

by TheRookie

Agreed, if you could get a hub geared hub down to a competitive weight of say 700g (roughly the same as a hub plus cassette plus RD and a small amount of chain) it would be a very nice option, shame the Rohloff is about 1550g (and has a damn heavy shift cable which is heavy enough to offset it's weight advantage over the Alfine).

Of course if you compare the 14 speed Rohloff to a 2x11 system it gets a bit closer as you have about 350g of FD cable and shifter, but it's still in the region of 1/2Kg heavier. Worse if you have an FS as you need a chain tensioner to accommodate chain growth.
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MikeDee
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Joined: Mon Dec 22, 2014 1:27 am

by MikeDee

TheRookie wrote:CVT's have horrible transmission efficiency, that is what they are disappearing from cars to be replaced by multi speed (7+) conventional auto's.


Not on a hybrid. The e-CVTs are are an amazing piece of engineering.

mattr
Posts: 4671
Joined: Fri May 25, 2007 6:43 pm
Location: The Grim North.

by mattr

The cvt bit still has horrendous efficiency. It just allows the motor, or engine to run more efficiently.
A trade off.

The last potential game changer was torotrack, which pretty much died on its arse for any small/medium application.

And FWIW most of the big players aren't investing in developing CVTs any further, pretty much a dead or dying technology now.

TheRookie
Posts: 926
Joined: Wed Jan 18, 2012 4:23 pm
Location: Midlands, United Kingdom

by TheRookie

MikeDee wrote:
TheRookie wrote:CVT's have horrible transmission efficiency, that is what they are disappearing from cars to be replaced by multi speed (7+) conventional auto's.


Not on a hybrid. The e-CVTs are are an amazing piece of engineering.

On the Toyota hybrids the CVT requires 3 inputs (road, IC engine and e-machine) where will your third come from?
Impoverished weight weenie wanna-be!
Budget 26" HT build viewtopic.php?f=10&t=110956

by Weenie


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