Next generation of Dura-Ace Di2

Discuss light weight issues concerning road bikes & parts.
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Dan Gerous
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by Dan Gerous

rollinslow wrote:
Wed Jan 08, 2020 2:11 am
Given that DA9100 is so good, I have also wondered whether Shimano will sit on this another year as well.

FWIW, a 10 tooth cog on road bikes for a 12th gear does not sound like Shimano at all (increased friction) so I think it will have to be something bigger than just taking MTB tech to a road bike. I also wonder if they will have a disc brake 2.0 and leap their rivals by fixing noise, pad rub, etc. I actually think if they improved the discs to a much higher standard than their rivals that would be more than just a 12cog.
I think 12 cogs is a given, but I hope they go the Campy way more than SRAM's. I'd be happy to keep current chainring combos and keep cassettes starting at 11t. I already like the range 11-30 and 11-32 cassettes provide but the jumps are a bit big on the 11-32, I can live with them but they would be tighter and much nicer with an additional cog IMO. Kinda like 11-28 when we jumped from 10 speeds to 11 speeds.

rollinslow
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by rollinslow

Dan Gerous wrote:
Wed Jan 08, 2020 3:30 am
rollinslow wrote:
Wed Jan 08, 2020 2:11 am
Given that DA9100 is so good, I have also wondered whether Shimano will sit on this another year as well.

FWIW, a 10 tooth cog on road bikes for a 12th gear does not sound like Shimano at all (increased friction) so I think it will have to be something bigger than just taking MTB tech to a road bike. I also wonder if they will have a disc brake 2.0 and leap their rivals by fixing noise, pad rub, etc. I actually think if they improved the discs to a much higher standard than their rivals that would be more than just a 12cog.
I think 12 cogs is a given, but I hope they go the Campy way more than SRAM's. I'd be happy to keep current chainring combos and keep cassettes starting at 11t. I already like the range 11-30 and 11-32 cassettes provide but the jumps are a bit big on the 11-32, I can live with them but they would be tighter and much nicer with an additional cog IMO. Kinda like 11-28 when we jumped from 10 speeds to 11 speeds.
Definitely agree with that. I have been very impressed with Super Record 12, running 50/34 with 11/29. Ever closer to perfection.
Moots Vamoots RSL (2019)-Dura Ace 9100
Cervelo S1 (2010)-Super Record 12 (viewtopic.php?f=10&t=161577)
Kestrel RT700 (2008)-Dura Ace 9000
Mosaic GT-1 (2020)-in build queue

by Weenie


ooo
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by ooo

I find is interesting, that Shimano never released R9100 or R8000 branded hubs (rim brake or disc brake)
May be they are thinking about thru-axles as single standard for both rim and disc brakes?
Last edited by ooo on Wed Jan 08, 2020 4:13 am, edited 2 times in total.
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TobinHatesYou
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by TobinHatesYou

ooo wrote:
Wed Jan 08, 2020 3:56 am
I find is interesting, that Shimano never released R9100 or R8000 branded hubs (rim brake or disc brake)
May be they are thinking about thru-axles as single standard for both rim and disc brakes?
I've asked this before, and I'll ask again. Why would they? It's not like they can share hub shells between 130mm and 135/"142"mm OLD frames unless you are betting on rim-brake bikes moving to 135mm. Sure they could do that, but why would you want to use a 135mm hub shell on a rim-brake bike in the first place...the odd case of someone rebuilding a disc hub into a rim-brake wheel with the rotor removed? Just how many people do we think might do this? Literal 10s of people maybe?

Are people really this deluded into thinking rim-brake bikes are getting odd/niche new standards? The big brands want you off rim brakes. Our current rim-brake bikes wouldn't be able to take advantage of this. This leaves a very small subset of "Never Disc" cyclists as the primary target customers.

ooo
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by ooo

Shimano don't want to have 135 QR on road bikes not for disc, not for rim brakes - in 2018-2019 they have removed all 135 disc hubs/wheels (FH-CX75, FH-RS505) and replaced them with thru-axles FH-RS770, FH-R7070, FH-RS470.

142x12 as single standard for both disc and rim bike frames will make it easier for shimano to make a group that works the same on both types of bikes (no chain rub on small-small chainring, no need to disable some combination on di2), and for bike manufacturer it is easier to have the similar design for rim brake and disc brake frames (same chainstay)
Last edited by ooo on Wed Jan 08, 2020 4:40 am, edited 2 times in total.
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TobinHatesYou
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by TobinHatesYou

ooo wrote:
Wed Jan 08, 2020 4:24 am
Shimano don't want to have 135 QR on road bikes not for disc, not for rim brakes - in 2018-2019 they have removed all 135 disc hubs/wheels (FH-CX75, FH-RS505) and replaced them with thru-axles FH-RS770, FH-R7070, FH-RS470.

142x12 as single standard for both disc and rim bike frames will make it easier for shimano to make a group that works the same on both types of bikes (no chain rub on small-small chainring, no need to disable some combination on di2), and for bike manufacturer it is easier to have the similar design for rim brake and disc brake frames (same chainstay)

It is much simpler for bike manufacturers to drop rim-brake bikes from their catalogs altogether, as many have already done.

Now if you show me evidence of this move being made at the other end of the Shimano product line...the Acera / Alivio / Tourney end, then I might ponder that for a second. Even then that is basically another world and there is no real need to consider cross-compatibility between those groups vs the Claris level stuff and above.

ooo
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by ooo

Shimano have released grx (including 10 speed) with special chainline crankset and front deraileur to fix some of this compromises
This year small Sora update is expected, they may have some changes in 9sp mechanical road disc group (or 9sp grx addition)
Thats why I mentioned Sora on previous topic page (it will be interesting to see what will be introduced) - viewtopic.php?f=3&t=156208&start=315#p1539482
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pdlpsher1
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by pdlpsher1

Sram's 10th cog concept is brilliant. Wide range gearing with a small compromise in efficiency. I need 1:1 gearing for some special climbs. I use a 11-34 HG-800 cassette for that purpose but the cassette is designed with gravel gearing and it comes with huge gaps. I don't even have 12, 14, and 16 cogs! Hence the 11-34 is not suitable for everyday riding and it's only good for special events. With the Sram AXS I can have 1:1 gearing on the low-end and have close ratios for everyday riding. A big win-win.

If Shimano doesn't adopt the same concept I'm going to switch from 9150 to Red AXS. Those that don't need the wide range gearing can stay happy on their non-Sram groups. There's no need to attack Sram's 10th cog concept.

TheRich
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by TheRich

pdlpsher1 wrote:
Wed Jan 08, 2020 4:59 am
Sram's 10th cog concept is brilliant. Wide range gearing with a small compromise in efficiency. I need 1:1 gearing for some special climbs. I use a 11-34 HG-800 cassette for that purpose but the cassette is designed with gravel gearing and it comes with huge gaps. I don't even have 12, 14, and 16 cogs! Hence the 11-34 is not suitable for everyday riding and it's only good for special events. With the Sram AXS I can have 1:1 gearing on the low-end and have close ratios for everyday riding. A big win-win.

If Shimano doesn't adopt the same concept I'm going to switch from 9150 to Red AXS. Those that don't need the wide range gearing can stay happy on their non-Sram groups. There's no need to attack Sram's 10th cog concept.
There is absolutely no upside to the 10t that couldn't have been addressed at the chainrings.

10t is great for mountain bikes, where you need to preserve some clearance between the chainring and things that will damage it and is very rarely used, road bikes don't have that problem.

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pdlpsher1
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by pdlpsher1

TheRich wrote:
Wed Jan 08, 2020 5:05 am
There is absolutely no upside to the 10t that couldn't have been addressed at the chainrings.
Could you come up with a possible solution for Shimano that contains 1) 1:1 gearing on the low-end, 2) high enough gearing for the top-end (i.e. 50x11), and 3) a close-ratio cassette with only changes made at the chainrings? I have thought this through and the only solution is the inclusion of the 10th cog and smaller chainrings.

ooo
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by ooo

@pdlpsher1, 10t is not needed for that, rotor have 12s cassette with same range and a little beter jumps with 11t cog:

Image

stock 11s sunrace 11-36 have can be used as alternative to 12s sram 10-33
or non-stock 11s shimano 11-35 (11-40 with 40t replace to 12) if you have dremel

Image
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pdlpsher1
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by pdlpsher1

That looks pretty good. The 36 is overkill. If Shimano comes out with a 12-speed cassette with 11-12-13-14-15-17-19-21-24-27-30-34 then that would be golden. But I fear Shimano will only do a 11-32 max on Dura Ace and I'm screwed again until the Ultegra 12-speed is released.

TobinHatesYou
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by TobinHatesYou

TheRich wrote:
Wed Jan 08, 2020 5:05 am

There is absolutely no upside to the 10t that couldn't have been addressed at the chainrings.

10t is great for mountain bikes, where you need to preserve some clearance between the chainring and things that will damage it and is very rarely used, road bikes don't have that problem.

1x gravel bikes basically. They are limited in terms of tire-chainstay-chainring clearance. I don't hate the 10t cog. I spend almost no time in the 11t cog right now other than at times where I'm basically on the verge of deciding to supertuck and coast anyway. I don't care about friction losses robbing my power, but do care a little bit about the wear-rate.

TheRich
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by TheRich

pdlpsher1 wrote:
Wed Jan 08, 2020 5:43 am
That looks pretty good. The 36 is overkill. If Shimano comes out with a 12-speed cassette with 11-12-13-14-15-17-19-21-24-27-30-34 then that would be golden. But I fear Shimano will only do a 11-32 max on Dura Ace and I'm screwed again until the Ultegra 12-speed is released.
Yeah, but if they decided to replace the 11-32 with 11-36 and used a 36 or 38/54 crankset, you get huge range with less drag than even 11-speed. Existing compact crankset gearing would be the new gravel setup.

The 10t on a road setup will increase chain wear and power loss, which is why it's ok for MTB, but not for road where the top gear is used a lot more.
TobinHatesYou wrote:
Wed Jan 08, 2020 6:07 am
1x gravel bikes basically. They are limited in terms of tire-chainstay-chainring clearance. I don't hate the 10t cog. I spend almost no time in the 11t cog right now other than at times where I'm basically on the verge of deciding to supertuck and coast anyway. I don't care about friction losses robbing my power, but do care a little bit about the wear-rate.
That's not really a road setup though.

TobinHatesYou
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by TobinHatesYou

TheRich wrote:
Wed Jan 08, 2020 6:10 am

That's not really a road setup though.

Yeah, it's not a pure road-race setup, but I do plan on running my future road/gravel/cx as 1x 44x10-50t and seeing if that will cut it when used as a rain bike on hammerfests. Other option is to just stick to 2x 48/32x11-36t or something like that. Anyway while SRAM hasn't introduced 11-Xt cassettes for their AXS groups, nothing prevents them from acquiescing to customer demands. We've already seen them offer 53/39 chainrings to the pros.

by Weenie


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