New Sram Red eTap AXS group

[yinzerniner]

Originally Posted by Mark McM

I can't really argue with this - the additional losses are quite small, and perhaps of no great concern to most cyclists. But on other hand, SRAM has gone to great lengths to re-work the drivetrain for no particular gain, either. Every design change results in compromise between positives and negatives. If the positives outweigh the negatives, then a change may be worth making. In this case, I don't see how the positives outweigh the negatives, so why change things?

I think the biggest change and hopeful efficiency and operational gain is the one people are overlooking - the chain.

Everyone is LEADING their articles on "12 SPEED FINALLY" instead of focusing on the chain. The complete redesign SUPPOSEDLY makes it stronger (more material in the flat top section where the load is highest), lower friction (with the increase roller size), longer life (possibly due to a combination of the above?) and narrower outside profile which leads to greater gap from the outside of the chain to the edges of the cassette (hopefully creates less friction and thus increases lifespan and improves shifting and drivetrain efficiency due to chainline improvement).

Then again, just redesigning the chain to work with previous hub, cassette and chainring standards might be possible, but then where is the revenue maximization going to come from?

Now whether the chain is ACTUALLY that much better, or if it is how much of a price premium people will pay for the increased performance, only time will tell. However that's true of everything. SRAM is only stating their gains now, and I"m sure people will test it out.

[Mark McM]

Originally Posted by yinzerniner

The CyclingTips article I posted previously shows that properly designed and implemented clutch RD's reduce friction. I'll post it again below, with the operative DEFINITIVE phrase being "And in fact, a clutch-equipped rear derailleur can actually produce less friction than a non-clutched rear derailleur, given the proper setup."

https://cyclingtips.com/2019/01/do-c...rain-friction/

Very interested in seeing how the ETAP AXS tests against Shimano Dura Ace Di2and EPS 12 speed when it comes to efficiency. That being said, the overall functionality and setup ease of ETAP trumps either system, even though it gives up shifting speed, overall manufacturing quality and customization to Di2 and shifting quality and ergonomics to EPS.

I have no idea how that article came to conclusion that a clutch derailleur decreases friction, when the data published with that article shows otherwise. The data shows drivetrain friction with a variety of derailleurs, in both smooth and rough conditions, with the clutch either on or off. In the "smooth" condition, there were sometimes very small decreases in friction when the clutch was on. But in rough conditions, there were always more substantial increases when the clutch was on. And even in the smooth conditions case, the friction changes when changing the cage tension was much more substantial than the differences between the clutch being on and off.

The data in this article actually shows that in terms of drivetrain losses, the clutch usually hurts more than it helps.

[vincenz]

I still can't get over the look of the compact and super compact chainrings. They just look bad on a performance road bike.

[Mark McM]

Originally Posted by yinzerniner

I think the biggest change and hopeful efficiency and operational gain is the one people are overlooking - the chain.

Everyone is LEADING their articles on "12 SPEED FINALLY" instead of focusing on the chain. The complete redesign SUPPOSEDLY makes it stronger (more material in the flat top section where the load is highest), lower friction (with the increase roller size), longer life (possibly due to a combination of the above?) and narrower outside profile which leads to greater gap from the outside of the chain to the edges of the cassette (hopefully creates less friction and thus increases lifespan and improves shifting and drivetrain efficiency due to chainline improvement).

Then again, just redesigning the chain to work with previous hub, cassette and chainring standards might be possible, but then where is the revenue maximization going to come from?

Now whether the chain is ACTUALLY that much better, or if it is how much of a price premium people will pay for the increased performance, only time will tell. However that's true of everything. SRAM is only stating their gains now, and I"m sure people will test it out.

Is there more information available on the new chain? Bicycle roller chains have used the same pitch (1/2") and roller (5/16") dimensions practically since the roller chain was first used. Changing either dimension would make the AXS chain, sprockets and chainrings totally incompatible with all current chains, sprockets and chainrings. And if they were going to change the roller diameter, why wouldn't they also change the pitch - using a shorter pitch would mean they could make smaller sprockets without having to use fewer teeth (and therefore avoid most of the efficiency losses of small sprockets).

Changing the fundamental chain dimensions isn't without precedent, as Shimano tried this with their 10mm pitch track drivetrain.

[yinzerniner]

Originally Posted by Mark McM

Is there more information available on the new chain? Bicycle roller chains have used the same pitch (1/2") and roller (5/16") dimensions practically since the roller chain was first used. Changing either dimension would make the AXS chain, sprockets and chainrings totally incompatible with all current chains, sprockets and chainrings. And if they were going to change the roller diameter, why wouldn't they also change the pitch - using a shorter pitch would mean they could make smaller sprockets without having to use fewer teeth (and therefore avoid most of the efficiency losses of small sprockets).

Changing the fundamental chain dimensions isn't without precedent, as Shimano tried this with their 10mm pitch track drivetrain.

Never said it's unprecedented, but it is interesting.

Looks like the flat-top chain is only approved for use with RED AXS cassettes, RDs and chainrings. Could possibly work with existing teeth on cassettes and sprockets as the inner diameters stay the same, but no one's tested it yet. When you go with Eagle AXS they recommmend to switch all three to Eagle components.

CyclingTips First Ride, go to the "What's Up With That Chain" for detailed info. https://cyclingtips.com/2019/02/sram...ap-axs-review/

SRAM Tech on RED AXS Chain. Doesn't get into all the dimensions
https://sram.zendesk.com/hc/en-us/se...03208294-CHAIN

CX Mag on the chain differences between Eagle and RED AXS. Drivetrain louder with Eagle, which uses the more traditional chain dimensions
https://www.cxmagazine.com/electric-...reverb-dropper

[Dave]

The article on the chain mentions changing the roller diameter slightly. That most likely means an insignificant change that would work with current sprockets and chain rings, as long as they are narrow enough. As for needing a different chain checker, no one needs anything more than a 12" precision rule to measure the increase in chain pitch.

The range comparisons show only minor improvements. Their 10-33 for example has fewer 1-tooth shifts than a Campy 11-32 and only has a little lower ratio because they chose to make a 28-33 jump instead of 28-32. The 46/33 has less range than a 50/34. There is no magic here, it's just a matter of picking what you want to offer. The top gear on both setups are nearly identical. The same goes for their 10-26 cassette. They use a 23-26 jump at the large end, instead of a 23-25, to gain some range.

https://www.campagnolo.com/media/fil...019_part_B.pdf

What's really LAME about these comparisons is they are comparing 12 speed to 11 speed. Of course you should have more range with 12 cogs instead of 11. A legitimate comparison would include Campy 12 speed. A Campy 11-29 has the same 7 one-tooth shifts and slightly more range than a SRAM 10-26.

[Davist]

Not from anything, but the BMX world has had "flat top" style chains for a few years, my question is when it bends "against the grain" via the top derailleur pulley, I wonder if it adds friction? (pic is of a 1/2 link version)

[Mark McM]

Originally Posted by Dave

The range comparisons show only minor improvements. Their 10-33 for example has fewer 1-tooth shifts than a Campy 11-32 and only has a little lower ratio because they chose to make a 28-33 jump instead of 28-33. The 46/33 has less range than a 50/34. There is no magic here, it's just a matter of picking what you want to offer. The top gear on both setups are nearly identical.

https://www.campagnolo.com/media/fil...019_part_B.pdf

And if you look closer, some of the "improvements" are actually deficits. Particularly shift size differentials, since differentials are not measured in the number of teeth difference, but instead in the relative size differences in sprockets. Shifting between a 10 and 11 tooth sprocket might seem the same as shifting between a 30 and 31 tooth sprocket, because both are only 1 tooth differences - but in reality going from 10 to 11 is a 10 percent change, whereas going from 30 to 31 is only a 3.3 percent change. The shift to that 10 tooth sprocket from the 11 will always be bigger than shifting from a 12 to the 11.

If you compare SRAM's 10-33 cassette with a "standard" 11-34 cassette, the SRAM sprockets might all be exactly 1 tooth smaller - but that doesn't mean that the gear size differences are maintained. The SRAM cassette might maintain the same number of 1 tooth, 2 tooth and 3 tooth shifts, but the actual size jumps between gears on the SRAM cassette are all larger. As you say, there's no magic - you can't increase gearing range without increasing the jumps between gear sizes.

There were similar conversations when Compact cranks first became popular. Some people believed they were magic - that they could somehow increase gearing range without increasing the size jumps between gears. But, of course, Compact cranks weren't magic either; you can't increase gearing range without increasing the jumps between gear sizes.

[Joxster]

Personally I like the way SRAM always compared everything to Shimano 11spd and ignored Campag 12spd as the advantages weren't as impressive on paper. Having sat through a powerpoint presentation on AXS and not once did they mention it was 12spd and I had to count the sprockets to make sure it was 12spd

[benb]

Pricing and repeated dissatisfaction with previous SRAM road groupsets mean I will never need to worry about any of the minutiae being argued about.

There are a couple thing in my personal experience that kill this for me...

- The smaller chainrings. Not a fan. They will wear out faster if we believe anything from mechanical engineering.. same stresses on fewer teeth. More wear + high costs sounds like a no-go. I'm sure that 12-speed chain will wear out even faster too. Maybe the cassette will last longer since their are more cogs and you'll probably ride a larger cog to balance out the smaller rings? But the cogs are thinner to which won't help durability, and surely they are expensive.

- Maybe they've solved the poor shifting of compact fronts as they've reduced the differential between the two rings. That'd be good. But they keep reinventing the wheel just to try and distract us from the fact they can't seem to just make front shifting systems that work correctly. 1X, electronic shifting, small rings, etc, etc.. how about just make a simple normal front setup that works as well as Shimano or Campy?

- My other issue with Compacts is *for me* I very very frequently find myself stuck in the middle of the two rings with a compact... whereas with a 53/39 + 12-25, 12-27, 12-28, etc.. I will be shifting the front less because of where the overlap in ranges occurs. This is actually worse with a narrower range cassette in the back as it requires more rear shifts to get to the correct gear when switching front chainrings. Besides that on a light bike a 53/39 has none of the negatives of a compact and with a 12-28 I can get over just about any paved road for hundreds of miles that I am actually allowed to ride on without paying a fee or signing up for a hill climb race, no matter how long the day is.

- I haven't rode eTap... I had not thought through the issues about their choice to make front shifting use both shifters... for me that is probably a deal breaker when you combine it with their use of compact cranks. The compact cranks mean I'm going to do more front shifts.. the gearing selections mean I likely need to do more rear shifts when I change the front derailleur to get to the correct gear ratio. And I apparently wouldn't be able to tell the system to concurrently shift the front and the rear together. I can shift the front and rear at the same time on most other systems including electronic shimano groups. (I have rode those and they work fine for me the way I shift.)

- There have been numerous references to "Pro This, Pro That" in this thread, I don't think this stuff is for them. This stuff has "MAMIL with money" written all over it with the focus on extreme low gear ranges. Since when do Pro Cyclists need 1:1 for road racing? And for Pros who have wheel sponsors the wheel sponsor is going to have to make/get new hubs before they can even use this.

- Since when do we even need clutches on the road? Only way I can get this is if they're trying to use the same stuff with 1X MTB/Gravel stuff. If they unify MTB/Gravel/Road groupsets into one giant compatible system that would be a GREAT thing for anyone who wants to run normal road racing gearing most of the time and then throw on a massive cassette or tiny rings to go ride Mt. Washington or something like that. If you could throw a different longer cage MTB derailluer on + cassette/chain and pair the whole thing up and just go with minimal work that'd be great.

I find it hilarious the article is complaining it's only been 4 years since eTap was announced.. I also long for the days when a groupset was current for 10 years and we didn't have this constant march of everything being changed in ways that made it incompatible when you needed to replace stuff.

[sitzmark]

Originally Posted by Mark McM

I have no idea how that article came to conclusion that a clutch derailleur decreases friction, when the data published with that article shows otherwise. The data shows drivetrain friction with a variety of derailleurs, in both smooth and rough conditions, with the clutch either on or off. In the "smooth" condition, there were sometimes very small decreases in friction when the clutch was on. But in rough conditions, there were always more substantial increases when the clutch was on. And even in the smooth conditions case, the friction changes when changing the cage tension was much more substantial than the differences between the clutch being on and off.

The data in this article actually shows that in terms of drivetrain losses, the clutch usually hurts more than it helps.

Additional data: https://youtu.be/z7TdWbjwzi0

[TunaAndBikes]

I don't have an opinion on things I can't afford, but it sure does like XTR M980.

[choke]

Originally Posted by yinzerniner

Very interested in seeing how the ETAP AXS tests against Shimano Dura Ace Di2and EPS 12 speed when it comes to efficiency. That being said, the overall functionality and setup ease of ETAP trumps either system, even though it gives up shifting speed, overall manufacturing quality and customization to Di2 and shifting quality and ergonomics to EPS.

I'm confused. How does the "overall functionality" of ETAP "trump" the other two systems when it gives up "speed, quality, customization and ergonomics"? It seems to me that the only thing you list that is better than the other two is "setup ease" and while that is a factor it's only done one time and IMO has zero bearing on the actual functionality while riding.

[Mark McM]

Originally Posted by sitzmark

Additional data: https://youtu.be/z7TdWbjwzi0

That video (about the same test as the CyclingTips article) doesn't actually present any data, but it does present a set of conclusions from the test. And those conclusions (starting at about 5:25 in the video) are pretty much the same conclusions I reached from the data - in smooth coniitions, the clutch doesn't change drivetrain losses, but under rough conditions, the clutch increases drivetrain losses. And that goes for both SRAM and Shimano clutch derailleurs.

The small extra losses may be good compromise for off-road drivetrains, if it prevents chain bounce. But, as the presenters in the video commented, there's no good reason to move to clutch derailleurs on road bikes.

[thirdgenbird]

Originally Posted by oldpotatoe

Ducati Scrambler-$9000
Trek Madone SLR disc-$12,000

Yeah, but the Trek has to go through all of that expensive EPA and Euro testing. Oh, wait...