Paulc

It is a tough one

Darth Lefty 

But hey, if SRAM can machine an entire cassette out of billet and get us to pay for it...

Kapusta

That simple? No its not.

You need a way to move the lever with the jockey wheel. But it is not a simple lever...

You also need a way to take up chain slack as you go between different cogs. So that jockey wheel shown is actually just the upper jockey in a tension arm (cage) like you see on a rear derailleur. So you are moving the whole cage.

What I just described is basically a rear derailleur in terms of complexity. The only real difference is that the linkage moves the jockey wheel vertically instead of at an angle.

So in addition to whatever is needed to make the cogs telescope, you still have something hanging off the bike just as complicated as a current RD.

And regarding the number of cogs: the current limit on cogs is not just the chain line at the extremes. It is also how much space the cassette takes up on the hub. This telescoping cassette takes up just as much room.

And regarding the shifts: the chainline currently does not really effect the shifts much. Shifts initiate at the jockey wheel (where the chain first contacts the cogs) On the current RD system it is already lined up perfectly straight with the cogs.

Kapusta

Hey, I’m sorry to come off so negative.

It IS and interesting and creative take on a way to solve a problem that I’ve not seen before.

I do have one suggestion that might make it more appealing (assuming it could work to start with):

Right now you have it broken into 2 parts. As a result, it takes up just as much room as a regular cassette, because at some point you need room for the full width of both halves. What if you broke it up into 3 or more smaller parts? It would still need to take up the width of two of those parts, but they would be narrower. That would reduce the amount of space needed on the hub, which would be a true advantage.

tyrion

I must disagree with you on this part - if the chain stays in a plane then a tension device is dead simple.

Teamprovicycle

I figured that at some point , some one or some company would make a chain ring that moves so the chain is strait at every postion and then we can use the 12 speed as a legit upgrade to 11 or less .

I think any idea to keep the chain strait is a step in the right direction , and if it can be made without great cost or special hubs then you will have a winning trend .

Kovkov

I have 6 bikes with a non crosschaining concept. It‘s called Sturmey Archer AW and works like a charm .

Darth Lefty 

It still needs to do three of the four functions of the rear derailleur, just not the pantograph.

And there still needs to be something like the pantograph or maybe a helical thing hooked up to a shifter to deploy the telescoping cassette.

tcarl

What do I think of it? 1. I'd like to see how it works mechanically. 2. It solves a problem I don't have - i.e. I can already ride/choose gears without cross chaining. 3. I mostly ride in flat land. I rarely use a cassette with a larger cog than 23 or 25 teeth. Will this work with something like a 13-14-15-16-17-18-19-21-23-25?

niels360

looks complicated to me

Kapusta

Yeah, I guess it would not need to be the slant-parallelogram. That part could be a single spring-tensioned pivot (similar to what the chain tension cage uses). But the rest (cable activation, chain tension cage, b-adjust screw, need for a clutch for some applications) is pretty much the same design as a current RD.

Kapusta

It is NOT a simple chain tension device. The position of the guide pulley needs to be moved and controlled. It may not need to move horizontally , but it does need to be positioned properly vertically, and change as you switch gears.

You could separate the guide pulley and the tension device and put the tension device elsewhere, but it is still the same amount of parts and complexity you are just separating them. Remember, the chain tension device needs to be spring loaded and have a wide range of motion in order to take up chain slack. Yes, this is not rocket science, it is basically like any spring loaded single speed or IGH tensioner, but the cage needs to be as long as one on a typical RD. And this is IN ADDITION TO the mechanism needed to control move the guide pulley.

And if this is on a MTB, then the tension device will probably need a clutch.

JohnDThompson 

Seems excessively complex. If you're that worried about the effects of cross-chaining, why not use an internally geared hub and eliminate the derailleur at the same time?