The only drive train I would spend a lot of money on
09-09-19, 08:52 PM
#76
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What CS did, and you can see it pretty clearly on their 2018 interbike demo, is replace all the 'teeth' on the shaft pinion 'gears' with individual bearings. It looks kinda like a flower, when viewed from the end. The teeth on the crank and cassette are shaped to drive and be driven by those circular bearing races.
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09-10-19, 04:07 PM
#77
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You save 8 secs. over 40 KM and for how much?
09-10-19, 06:35 PM
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That 8 seconds could be worth half a million bucks $$ if the 40 KM ends on the Champs-Élysées
09-11-19, 11:07 AM
#80
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There could be many reasons why the prototype needed external power.
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09-11-19, 04:11 PM
#81
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My, my, would you look at this ... everything old is new again.
https://www.gracesguide.co.uk/File:I...art-Page91.jpg
https://www.gracesguide.co.uk/File:I...art-Page91.jpg
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09-13-19, 01:56 AM
#84
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Engineer here. I doubt that it needs constant power. The video shows that changing the gears involves turning a screw. There's no reason that power would be needed to maintain the rotated position of a screw.
There could be many reasons why the prototype needed external power.
There could be many reasons why the prototype needed external power.
09-13-19, 02:29 AM
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Chainless drives have been around for well over 100 years.
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09-13-19, 07:34 AM
#86
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Pretty much all of the previous shaft drive systems have used bevel gears, ie: teeth-on-teeth. Whether it's been straight cut or helical, it's pretty much like what you'd find in a shaft-drive moto, just smaller scale.
What CS did, and you can see it pretty clearly on their 2018 interbike demo, is replace all the 'teeth' on the shaft pinion 'gears' with individual bearings.
What CS did, and you can see it pretty clearly on their 2018 interbike demo, is replace all the 'teeth' on the shaft pinion 'gears' with individual bearings.
I appreciate what CS has done here, but shaft driven bikes went out of favor for a lot of good reasons. The main one being that you can't make a rear triangle stiff enough to make it work well. And it seems like CS is limited to 250 watts at this point because of that. OTOH, I am impressed they made it shift, didn't think that was going to happen
I think the reason it was plugged in was that they didn't want batteries to die in the middle of a big show. And they probably haven't developed their own batteries yet. It will be interesting to see if this ever makes it to market. I thought it was just a PR stunt last year, but it sure looks like they are serious about it now.
Last edited by unterhausen; 09-13-19 at 07:38 AM.
09-13-19, 09:25 AM
#87
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The screw is going to be how they vary the length, but the angle is also going to have to vary as it shifts from cog to cog. With the contacts limited to one bearing at the crank and cog, this is going to be very precise or it won't work. The bike, the cogs, the crank are going to be moving, encountering bumps, turns, stops and starts. Isn't this going to require constant microadjustment to maintain the contacts?
09-13-19, 10:31 AM
#88
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Bear with me as I'm an admitted technical idiot, and I'm quite possibly wrong about this, and even if I am correct, I don't have the language to describe it adequately.
Basically, this is a high-tech egg beater lateral to the frame of the bike--when the crank is turned, the not-chain-ring "meshes" with bearings on the front end of the shaft, turning the shaft, which turns a wheel in the back with bearings that "mesh" with the cogs.
The smaller the cog, the farther it is from the center of the axle. So not only does the shaft have to be longer or shorter to shift gears, it also needs to move away further from the wheel to reach the smaller cogs. I assume there's an optimal amount of pressure being applied from the bearing to the ring/cog where there is just enough to transmit the energy but without introducing extraneous friction, so the angle I'm talking about is the one from the center line of the bike lengthwise to the shaft.
Basically, this is a high-tech egg beater lateral to the frame of the bike--when the crank is turned, the not-chain-ring "meshes" with bearings on the front end of the shaft, turning the shaft, which turns a wheel in the back with bearings that "mesh" with the cogs.
The smaller the cog, the farther it is from the center of the axle. So not only does the shaft have to be longer or shorter to shift gears, it also needs to move away further from the wheel to reach the smaller cogs. I assume there's an optimal amount of pressure being applied from the bearing to the ring/cog where there is just enough to transmit the energy but without introducing extraneous friction, so the angle I'm talking about is the one from the center line of the bike lengthwise to the shaft.
09-14-19, 06:25 AM
#89
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The smaller the cog, the farther it is from the center of the axle. So not only does the shaft have to be longer or shorter to shift gears, it also needs to move away further from the wheel to reach the smaller cogs. I assume there's an optimal amount of pressure being applied from the bearing to the ring/cog where there is just enough to transmit the energy but without introducing extraneous friction, so the angle I'm talking about is the one from the center line of the bike lengthwise to the shaft.
CS's 'driver' is flat. All the cogs are concentric rings of teeth that stick out from the same plane.
The shaft doesn't have to move, but the pinion moves back and forth along the shaft to engage each 'gear' It would appear they're using some sort of diamond screw to accomplish that stepping action.
Last edited by Ironfish653; 09-14-19 at 06:35 AM.
09-14-19, 08:45 AM
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I have to say that at first I thought the rear gear was conical. Maybe they had a conical version at some point? Still looks conical in some shots.
I am assuming that they are smart enough to use a lead screw that doesn't need constant force to stay in position. Most lead screws can't be back driven very well, and I don't see the forces here that would do it anyway. Of course, there still can be an issue with backlash and deflection of the frame.
I am assuming that they are smart enough to use a lead screw that doesn't need constant force to stay in position. Most lead screws can't be back driven very well, and I don't see the forces here that would do it anyway. Of course, there still can be an issue with backlash and deflection of the frame.
