New Sram Red eTap AXS group

[mattsurf]

As a very keen, pretty competent, middle age, high income cyclist, I am bull's eye target market for this groupset, and honestly I will probably end up getting one (could be shimano, Campy or SRAM) at some point in the future. However, I am also an engineer, and pretty realistic about what I would be getting. Will it make me faster? absolutely not.

Also, I feel that SRAM are making a massive mistake making all parts proprietary, the beauty of the 11 speed is that campy, Shimano and SRAM are pretty much compatible with each other, but with 12 speed setups, I am not going to be able to swap bikes on my Turbo Trainer, swap wheels, cassettes etc.... actually I think I may stick with 11 speed for some time to come

[shoota]

Originally Posted by R3awak3n

https://www.bikeradar.com/us/road/ge...hifting-44016/

THanks for the link. I guess that's why sram is claiming their resigned cogs and chain eliminate that friction inefficiency.

[Mark McM]

Originally Posted by shoota

Inefficient in what way? Serious question. SRAM is claiming there is no efficiency loss with this group.

They can claim all kinds of things, that doesn't make them true. It has been shown in many times and in many tests that smaller sprockets/chainrings have more losses. Given that this has been well established, it is up to SRAM to provide evidence of their claims, and they have not.

[Mark McM]

Originally Posted by shoota

I couldn't disagree more, the 10T is a game changer. It enables a much smaller chainring which then enables a smaller big cog for the equivalent low and high end of a 53/39, all with a tighter cassette. It's literally better in every way.

That's not really true at all. SRAM is claiming that this new gearing provides as wider or wider gear range, but with tighter spacing between gears - this is a physical impossibility. In fact, if you look closer, you'll find the opposite is true.

Let's compare SRAM's 10-33 12spd cassette (their widest range) with an 11-34 12 speed cassette. The 10-33 has a gearing range of 330% range, while the 11-34 has a gearing range of only 309%. SRAM did this changed the sizes of the smallest and largest by only 1 tooth each, which makes it appear that the gearing size differences would remain constant. But what matters isn't the absolute number of teeth between gear sizes, the relative change in sprocket sizes. The 10-33 cassette has an average of 11.5% difference in gear jumps, while the 11-34 has a difference of only 10.8%.

But SRAM didn't just change the cassette, they also changed the front chainrings. And the major change was to decrease the size differential between chainrings. So, instead of the 50-34 as the smallest 'compact' chainrings, SRAM has 46-33. Let's take a look at these:
When combined with 50-34 chainrings, an 11-34 cassette gives a high ratio of 4.54:1 and low ratio of 1:1. For SRAM, the 46-33 chainrings when combined with a 10-33 cassette gives a high ratio of 4.60:1 and a low ratio of 1:1. So both give the same low ratio, and nearly the same high ratio. So SRAM doesn't really give a wider total gear range. But while SRAM has a smaller jump between front chainrings, they have bigger jumps between rear sprockets. Since most people shift the rear more often the front, for most practical purposes SRAM has bigger jumps between gears, without any real increase in gearing range.

[yinzerniner]

Originally Posted by Mark McM

That's not really true at all. SRAM is claiming that this new gearing provides as wider or wider gear range, but with tighter spacing between gears - this is a physical impossibility. In fact, if you look closer, you'll find the opposite is true.

Let's compare SRAM's 10-33 12spd cassette (their widest range) with an 11-34 12 speed cassette. The 10-33 has a gearing range of 330% range, while the 11-34 has a gearing range of only 309%. SRAM did this changed the sizes of the smallest and largest by only 1 tooth each, which makes it appear that the gearing size differences would remain constant. But what matters isn't the absolute number of teeth between gear sizes, the relative change in sprocket sizes. The 10-33 cassette has an average of 11.5% difference in gear jumps, while the 11-34 has a difference of only 10.8%.

But SRAM didn't just change the cassette, they also changed the front chainrings. And the major change was to decrease the size differential between chainrings. So, instead of the 50-34 as the smallest 'compact' chainrings, SRAM has 46-33. Let's take a look at these:
When combined with 50-34 chainrings, an 11-34 cassette gives a high ratio of 4.54:1 and low ratio of 1:1. For SRAM, the 46-33 chainrings when combined with a 10-33 cassette gives a high ratio of 4.60:1 and a low ratio of 1:1. So both give the same low ratio, and nearly the same high ratio. So SRAM doesn't really give a wider total gear range. But while SRAM has a smaller jump between front chainrings, they have bigger jumps between rear sprockets. Since most people shift the rear more often the front, for most practical purposes SRAM has bigger jumps between gears, without any real increase in gearing range.

I'm sure there was a pretty big business decision to go to the XDr hub design instead of just sticking with 11 as the smallest sprocket. They probably could have accomplished the exact same goals in terms of drivetrain efficiency, cadence and range but it would have been more expensive on the manufacturing side since they'd have to make larger cassettes and chainrings, which leads to more material waste as both have a lot of one-piece construction. Also, the don't get to sell new freehubs to everyone.

That being said I'm also sure that the 2x FD with a clutch / damper RD works better with the smaller 13t max jumps at the front, so combining the improved FD shifting (which has always been a SRAM weakpoint) with the economic concerns it was a no-brainer from a business standpoint.

Originally Posted by Mark McM

They can claim all kinds of things, that doesn't make them true. It has been shown in many times and in many tests that smaller sprockets/chainrings have more losses. Given that this has been well established, it is up to SRAM to provide evidence of their claims, and they have not.

Addressed this in an earlier post, as the "larger sprockets/chainrings are more efficient" argument isn't necessarily true, just that all the test done with existing equipment shows that with that equipment the larger items test better. However that testing was done with non-clutch/damper RDs, current cassettes and typical 11s chains. All three of those variables have been changed with the new AXS group.

Not saying that it won't bear out that larger won't be better in terms of efficiency with AXS, just that it hasn't been tested yet.

[Mark McM]

Originally Posted by yinzerniner

I'm sure there was a pretty big business decision to go to the XDr hub design instead of just sticking with 11 as the smallest sprocket. They probably could have accomplished the exact same goals in terms of drivetrain efficiency, cadence and range but it would have been more expensive on the manufacturing side since they'd have to make larger cassettes and chainrings, which leads to more material waste as both have a lot of one-piece construction. Also, the don't get to sell new freehubs to everyone.

I'm pretty sure the XD and XDr hub designs were orginally intended for single chainring applications. In order to get a wide gear range with a single chainring, you either need very large sprockets (with a large chainring) or very small sprockets (with a small chainring). It was probably thought to be easier to use 9 and 10 tooth sprockets, instead of 50 and 60 tooth chainrings.

Originally Posted by yinzerniner

That being said I'm also sure that the 2x FD with a clutch / damper RD works better with the smaller 13t max jumps at the front, so combining the improved FD shifting (which has always been a SRAM weakpoint) with the economic concerns it was a no-brainer from a business standpoint.

Quite possibly. Many new design concepts involve compromises, and often some lesser benefits have to sacrificed to gain greater benefits. There have been many examples of this: Dual pivot brakes have higher leverage and are easier to keep in adjustment than single pivots, but they are also heavier and have smaller rim/pad clearances; indexed shifters/derailleurs are more complicated and more expensive (and also usually heavier) than friction shifters, but can provide faster/more precise shifting; etc. SRAM may believe the benefits of this system outweigh the deficits, and they may be right - but that doesn't mean there are no deficits, or give them free reign to make silly claims.

Originally Posted by yinzerniner

Addressed this in an earlier post, as the "larger sprockets/chainrings are more efficient" argument isn't necessarily true, just that all the test done with existing equipment shows that with that equipment the larger items test better. However that testing was done with non-clutch/damper RDs, current cassettes and typical 11s chains. All three of those variables have been changed with the new AXS group.

Since previous tests were done with then current best available components for 7spd, 8spd, 9spd, 10spd and 11spd equipment, there's little reason to believe that 12spd components will behave any differently.

Tests have shown that clutch derailleurs don't increase drivetrain losses, but so far it has only been hypothesized that they can decrease losses. No definitive proof has yet been given. And if they do improve efficiency, it is not limited to this 12spd system.

[shoota]

Originally Posted by Mark McM

*clipped*

I've read and re-read all your comments on this page and I'm not convinced you are correct about most of it. Maybe you're correct "on paper" but in real life scenario I'm not sure. I think the inefficiencies everyone is talking about are minuscule. I seriously doubt a pro team would accept a system that instantly puts them at a disadvantage. They go to many great lengths to squeeze out every drop of marginal gains for that.

[doubleklobbs]

Originally Posted by shoota

I seriously doubt a pro team would accept a system that instantly puts them at a disadvantage. They go to many great lengths to squeeze out every drop of marginal gains for that.

They often accept things that put them at a disadvantage because of sponsor money. See teams with bike sponsors like 3T, Look, or Cervélo. Each respective team quibbled with the performance of these, but stuck with them despite vocal frustration from their riders.

The World Tour acts as advertising for brands first, and R&D for brands second. The pro peloton's equipment would be far far less varied if every team just went out and bought what they thought was the best equipment.

[Davist]

Originally Posted by shoota

I seriously doubt a pro team would accept a system that instantly puts them at a disadvantage. They go to many great lengths to squeeze out every drop of marginal gains for that.

Aqua Blue and 1x maybe? that seems to have fizzled...

[Mark McM]

Originally Posted by shoota

I've read and re-read all your comments on this page and I'm not convinced you are correct about most of it. Maybe you're correct "on paper" but in real life scenario I'm not sure. I think the inefficiencies everyone is talking about are minuscule. I seriously doubt a pro team would accept a system that instantly puts them at a disadvantage. They go to many great lengths to squeeze out every drop of marginal gains for that.

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?

[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

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)