Next generation of Dura-Ace Di2

Discuss light weight issues concerning road bikes & parts.
ooo
Posts: 930
Joined: Sat May 21, 2016 12:59 pm

by ooo

Shimano ordered certification for new small low power 3.25×8.55mm transmitter with BTLE5.0/ANT antenna (made by taiyoyuden)
Current di2 uses older 5.1×11.3mm transmitter with BTLE4.2/ANT antenna (also made by taiyoyuden) for powermeter and smartphone connection.
Shimano documentation for new transmitter will be confidential until 23.03.2021. Certification process will be finished much sooner.

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Taiyoyuden documentation for old transmitter vs new transmitter:
old chip:Nordic nRF51422+old cpu:16MHz ARM vs new chip:Nordic nRF52832+new cpu:64MHz ARM

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Other bigger transmitters with nRF52 chips can be connect in low-rate wireless personal area networks (LR-WPAN or IEEE 802.15.4).
After quick look at Taiyoyuden documentation for this small 3.25×8.55mm transmitter, I was not able to find network support info.
'

by Weenie


bas
Posts: 98
Joined: Thu Jun 30, 2016 3:58 am

by bas

madik wrote:Strong argument for a pretty soon R9200 release are missing new Giant TCR models with Dura Ace di2/mechanical. The highest model with Shimano components are with Ultegra di2 and Giants flagship is with Sram Red eTap AXS. So If the new DA would have been moved to the next year I am pretty sure that Giant would have Dura Ace R91xx models in their catalogue already.
Last year's top models for Giant were all SRAM too though weren't they? I'm about to pull the trigger on an advanced pro TCR with ultegra di2, assuming that it will be at least a year until the SL models arrive with 12 speed DA

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Unniti
Posts: 222
Joined: Wed Mar 25, 2020 3:35 pm

by Unniti

So SRAM has thrown in the towel on traditional front derailleurs because they can't get one to work and/or went full integration because there still are people that have found a way to not use their AXS rings :D

TobinHatesYou
Posts: 5701
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

Unniti wrote:
Wed Jun 17, 2020 8:40 am
So SRAM has thrown in the towel on traditional front derailleurs because they can't get one to work and/or went full integration because there still are people that have found a way to not use their AXS rings :D

I like the idea of pushing the limits with electronic intelligence. Also this decouples the FD from the frame, which has clear benefits WRT frame design and frame protection. Also with the ramp + "snaggletooth" upshift electronically timed, it should create very, very smooth shifts indeed.

talltales
Posts: 117
Joined: Mon Mar 11, 2019 10:43 pm

by talltales

Seems to add a lot of complexity, cost and likely weight, - to solve what problem exactly?

aeroisnteverything
Posts: 362
Joined: Fri Aug 24, 2018 4:43 pm

by aeroisnteverything

I think weight should be OK - there is no reason why this cannot be made lighter or same-ish weight as the current derailleurs. Whether one upshift per revolutions is really sufficient - I don't know. Not sure how "laggy" that would feel in the real world. The problem I see is that just like with the integrated power meter, you are making a wearable part very very expensive and one that needs to be replaced whole, instead of just replacing the chainrings. Pretty wasteful.

I, for one, would prefer them to focus on 1x14 but put some thought into mitigating chain line efficiency losses. E.g. - can one come up with some sort of mechanism that moves the chainring along the pedal axle inward or outward depending on which rear cog is selected? Or change the angle of the chainring?

TobinHatesYou
Posts: 5701
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

aeroisnteverything wrote:
Wed Jun 17, 2020 9:37 am
I think weight should be OK - there is no reason why this cannot be made lighter or same-ish weight as the current derailleurs. Whether one upshift per revolutions is really sufficient - I don't know. Not sure how "laggy" that would feel in the real world. The problem I see is that just like with the integrated power meter, you are making a wearable part very very expensive and one that needs to be replaced whole, instead of just replacing the chainrings. Pretty wasteful.

I, for one, would prefer them to focus on 1x14 but put some thought into mitigating chain line efficiency losses. E.g. - can one come up with some sort of mechanism that moves the chainring along the pedal axle inward or outward depending on which rear cog is selected? Or change the angle of the chainring?
SRAM has a patent for a hinged chainring where the side that's currently meshed / under torque bends in either direction.

Suntour also did this a long time ago, which is sort of a combination of the movable chainring concept + shifting.

https://www.youtube.com/watch?v=stCbRXWdSEo

I don't think the new SRAM patent is anything more than a proof of concept, but I love the idea of a more self-contained shifting drivetrain that doesn't require specific frame design.

pmprego
Posts: 378
Joined: Mon Jan 21, 2019 3:16 pm

by pmprego

TobinHatesYou wrote:
Wed Jun 17, 2020 10:06 am
aeroisnteverything wrote:
Wed Jun 17, 2020 9:37 am
I think weight should be OK - there is no reason why this cannot be made lighter or same-ish weight as the current derailleurs. Whether one upshift per revolutions is really sufficient - I don't know. Not sure how "laggy" that would feel in the real world. The problem I see is that just like with the integrated power meter, you are making a wearable part very very expensive and one that needs to be replaced whole, instead of just replacing the chainrings. Pretty wasteful.

I, for one, would prefer them to focus on 1x14 but put some thought into mitigating chain line efficiency losses. E.g. - can one come up with some sort of mechanism that moves the chainring along the pedal axle inward or outward depending on which rear cog is selected? Or change the angle of the chainring?
SRAM has a patent for a hinged chainring where the side that's currently meshed / under torque bends in either direction.

Suntour also did this a long time ago, which is sort of a combination of the movable chainring concept + shifting.

https://www.youtube.com/watch?v=stCbRXWdSEo

I don't think the new SRAM patent is anything more than a proof of concept, but I love the idea of a more self-contained shifting drivetrain that doesn't require specific frame design.
Incurring the risk of just repeating others, these 2 comments are, for me, the most correct.

Companies patent stuff just to put others "out of the market" or out of the patent. If someone tries to market something similar, this way they can just cash in with that.

IMO, the 1x14 would make much more sense but with a movable front ring and I also hope they go this way.

Ritxis
Posts: 468
Joined: Fri Jun 01, 2012 3:00 pm
Location: San Sebastian

by Ritxis

Alfus wrote:
Wed Jun 17, 2020 8:08 am
New movement from SRAM

https://cyclingtips.com/2020/06/radical ... railleurs/

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Shimano has a patent for derailleur integrated in the cranks for months

I think I uploaded a photo from the PDF
I can open them this afternoon, and I also see the patent number

Ritxis
Posts: 468
Joined: Fri Jun 01, 2012 3:00 pm
Location: San Sebastian

by Ritxis

I uploaded this picture last August, in a Spanish forum
IMG_20200617_135052859.jpg

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Alexbn921
Posts: 501
Joined: Wed Apr 10, 2019 6:39 pm

by Alexbn921

This a great idea and looks to be a very smart execution. This would give you perfect repeatable front shifts every time and open up frame design like it has on mountain bikes. I would buy it.
The downside is price, but Sram doesn’t care about that and complexity. Setup with wireless would be so easy and I think if it’s executed correctly it will be better/faster.
I see this making it to production.

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itsacarr
Posts: 847
Joined: Fri Nov 14, 2008 4:55 am
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by itsacarr

Anyone have a guess on how this impacts chainring replacement based on these schematics? I assume based off this you would have to run a powermeter by the same group manufacturer correct?

Thought experiment or not, fascinating.

pmprego
Posts: 378
Joined: Mon Jan 21, 2019 3:16 pm

by pmprego

Alexbn921 wrote:
Wed Jun 17, 2020 4:03 pm
This a great idea and looks to be a very smart execution. This would give you perfect repeatable front shifts every time and open up frame design like it has on mountain bikes. I would buy it.
The downside is price, but Sram doesn’t care about that and complexity. Setup with wireless would be so easy and I think if it’s executed correctly it will be better/faster.
I see this making it to production.
Why can't a 1x front ring just slide sideways? The system could just be kept within the bb. I'm no engineer and I can easily be making a stupid mistake but it does sound simpler to me.

by Weenie


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Alexbn921
Posts: 501
Joined: Wed Apr 10, 2019 6:39 pm

by Alexbn921

pmprego wrote:
Wed Jun 17, 2020 4:27 pm
Why can't a 1x front ring just slide sideways? The system could just be kept within the bb. I'm no engineer and I can easily be making a stupid mistake but it does sound simpler to me.
That doen't change the gear ratio and having a ring that changes would have too much flex/complexity. Plus you would run into frame clearance issues.

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