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Vid: SRAM's development of 1x12 Eagle, and what SRAM needs to do next for us Tri-folks
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OK, that's great and all and I'm sure some 1x triathletes would love to see 1x12 (though 1x13 would allow better gear jumps for an 11-42t cassette), but SRAM, this is what we need to come out of that fancy Schweinfurt development facility:

A single front chainring with a continually variable transmision (cvt) in a single cog that operated by a wireless servo motor and that slides onto existing Shimano/SRAM freehub bodies.

An example of a cvt chainring can be found here: http://www.wavetransmission.com/.

But, I am proposing the cvt chainring be a rear cog, this way users are not limited to a particular crankset or limited as to powermeter choice; and, as a manufacturer, only dealing with a cassette based cvt cog simplifies production vs a crankset with different bottom bracket standards. The idea is to have an 11t-46t range. This would require sections of cog teeth sitting to the side of the cog when the cog is at smaller cog sizes. These sections of cog teeth move inwards and up or downwards and out at a rate faster than the expansion or contraction of the cvt cog to produce either a larger or smaller cog with greater or less numbers of teeth - I propose an aluminum or compressed carbon cog with u-shaped track on which the extra sections of teeth follow and moved by a simple servo motor with a wireless battery. The current freebody width would provide enough space for the cvt cog, its additional sections of cog teeth, the servo motor and the wireless battery, with no need for the consumer to purchase a special hub, freehub body or crankset. And, there would be a chain tensioner, like Paul's Melvin.

The advantages are a) a single straight chain line with a stronger, wider non-11/12sp chain, b) continuous gear range with no power loss during gear ratio changes, c) much more effective gear ratio changes when the drivetrain is under high torque, d) appeals to consumer desire for a wireless drivetrain, d) very large gear-inch range, and e) with automatic shifting on the very near horizon (Shimano synchro shift, Proshift), this cvt cog is best suited to provide the best automatic shifting experience.

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Last edited by: milesthedog: Jan 23, 17 7:57
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Re: Vid: SRAM's development of 1x12 Eagle, and what SRAM needs to do next for us Tri-folks [milesthedog] [ In reply to ]
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If you eliminate spider based power meters there are still plenty of other options: pedals (powertap etc), rear hub (powertap), and spindle (Rotor 2InPower).

Just use variable chainrings for both the front and the rear that way you don't need a chain tensioner.
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Re: Vid: SRAM's development of 1x12 Eagle, and what SRAM needs to do next for us Tri-folks [GreenPlease] [ In reply to ]
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yeah, but a) that's heavier, and b) there's something nice about giving people a product where all they have to do is remove their current FD, RD, cassette, chain and pop this cvt cassette, chain and chain tensioner on

But, your idea would simplify my rear cassette idea (no need for extra sets of teeth that move in and out) and not having the chain tensioner would be really nice. And, if developed by SRAM, they could create a quarq spider that were integrated into the cvt front chainring. So I concede, the duo front/rear cvt ring/cog could be a better idea.

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Last edited by: milesthedog: Jan 23, 17 8:11
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Re: Vid: SRAM's development of 1x12 Eagle, and what SRAM needs to do next for us Tri-folks [milesthedog] [ In reply to ]
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milesthedog wrote:
OK, that's great and all and I'm sure some 1x triathletes would love to see 1x12 (though 1x13 would allow better gear jumps for an 11-42t cassette), but SRAM, this is what we need to come out of that fancy Schweinfurt development facility:

A single front chainring with a continually variable transmision (cvt) in a single cog that operated by a wireless servo motor and that slides onto existing Shimano/SRAM freehub bodies.

Nah, the Eagle system is a selection of closer ratio cassettes away from being pretty near perfect for triathlon.

The only cassette currently available has a 500% spread, which is way more than needed for triathlon. Even an 11-42 would probably be a little more range, (381%), than necessary. Your common 50/34 compact, 52/36 mid-compact, and standard 53/39 crank sets with an 11-28 cassette have ranges of 374%, 367% and 345%, respectively.

A choice of 10-36, 10-34, and 11-32 would probably get the job done for most triathletes in most situations without having to change the single front chain ring size.

"They're made of latex, not nitroglycerin"
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Re: Vid: SRAM's development of 1x12 Eagle, and what SRAM needs to do next for us Tri-folks [gary p] [ In reply to ]
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Yes, apologies, I was thinking for 1x road in that scenario. anyways, no way the current geared shifting could outdo a cvt system.

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Re: Vid: SRAM's development of 1x12 Eagle, and what SRAM needs to do next for us Tri-folks [milesthedog] [ In reply to ]
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milesthedog wrote:
Yes, apologies, I was thinking for 1x road in that scenario. anyways, no way the current geared shifting could outdo a cvt system.

Depends on what you mean by "outdo." Theoretically perfect ratio for any demand within the ratio range? Sure. Practically? We're a long way from having any kind of bike CVT that has range, efficiency, and reliability of the tried-and-true chain/multi-cog cassette/rear derailleur combo.

"They're made of latex, not nitroglycerin"
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Re: Vid: SRAM's development of 1x12 Eagle, and what SRAM needs to do next for us Tri-folks [gary p] [ In reply to ]
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gary p wrote:
milesthedog wrote:

OK, that's great and all and I'm sure some 1x triathletes would love to see 1x12 (though 1x13 would allow better gear jumps for an 11-42t cassette), but SRAM, this is what we need to come out of that fancy Schweinfurt development facility:

A single front chainring with a continually variable transmision (cvt) in a single cog that operated by a wireless servo motor and that slides onto existing Shimano/SRAM freehub bodies.



Nah, the Eagle system is a selection of closer ratio cassettes away from being pretty near perfect for triathlon.

The only cassette currently available has a 500% spread, which is way more than needed for triathlon. Even an 11-42 would probably be a little more range, (381%), than necessary. Your common 50/34 compact, 52/36 mid-compact, and standard 53/39 crank sets with an 11-28 cassette have ranges of 374%, 367% and 345%, respectively.

A choice of 10-36, 10-34, and 11-32 would probably get the job done for most triathletes in most situations without having to change the single front chain ring size.


Ok so I am currently running an XT 11-40 (363%) on my road bike. I was really nervous about putting it on due to the gaps, but after a couple rides on it, I notice the gaps, but they don't really bother me. Gears are: 11-13-15-17-19-21-24-27-31-35-40.


That said, I wouldn't mind 12 or 13 gears to cover that same range.

/kj

http://kjmcawesome.tumblr.com/
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Re: Vid: SRAM's development of 1x12 Eagle, and what SRAM needs to do next for us Tri-folks [kjmcawesome] [ In reply to ]
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kjmcawesome wrote:
gary p wrote:


A choice of 10-36, 10-34, and 11-32 would probably get the job done for most triathletes in most situations without having to change the single front chain ring size.


Ok so I am currently running an XT 11-40 (363%) on my road bike. I was really nervous about putting it on due to the gaps, but after a couple rides on it, I notice the gaps, but they don't really bother me. Gears are: 11-13-15-17-19-21-24-27-31-35-40.


That said, I wouldn't mind 12 or 13 gears to cover that same range.

I'm curious to know what size chain ring you are running up front.

With 12 speeds, you could have pretty much the same gear spread with a 10-36 cassette and a 4-tooth smaller front chain ring, while closing those most noticeable gaps at the top end. I'm thinking the cogs would be like this: 10-11-12-13-14-16-18-21-24-28-32-36. A very strong rider might want a 48 tooth front ring, while us mortals might chose something more like a 44.

"They're made of latex, not nitroglycerin"
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Re: Vid: SRAM's development of 1x12 Eagle, and what SRAM needs to do next for us Tri-folks [gary p] [ In reply to ]
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I currently run a 44t front ring. I was previously running an 11-32 cassette. I think a 46t or 48t front ring would work with my 11-40 setup.

44x10-36 would work great for me.

/kj

http://kjmcawesome.tumblr.com/
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