New Sram Red eTap AXS group

[93KgBike]

Well, GM Finance is worth several times what GM is worth. I guess the big bike groups are trying to get into finance.

20 years ago, you could buy a top of the line Triumph sport bike for less than what you 'd spend for a top of the line Trek, today.



Cool tech, however. *sighs*

[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.

[Mark McM]

Originally Posted by EDS

10 teeth may be more inefficient than 11 but for the short life I believe most riders will spend a fraction of the time in their biggest gear versus the middle of the cassette. At least I know that is true of my riding, even though in my case that gear is 53x12.

While true in theory, in practice this won't be way it works out. For most people, a 52 x 10, or even a 50 x 10, is higher than they'd ever need. So, for most people, the 10 tooth sprocket will just give an opportunity to use smaller chainrings (for lower low gears, or just for tigher spacing between gears) without a loss of high end gearing. So typically, with this groupset people will be using smaller chainrings then they would if the smallest sprocket was 11 or 12. And with smaller chainrings, they will spend more time in smaller sprockets. So they will have lower drivetrain efficiency all the time, not just when in the 10 tooth sprocket.

[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.

[Lanternrouge]

Originally Posted by 93KgBike

20 years ago, you could buy a top of the line Triumph sport bike for less than what you 'd spend for a top of the line Trek, today.



Cool tech, however. *sighs*

I'm wondering how much the prices of high end bikes have increased relative to high end cars.

[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.

[choke]

Originally Posted by 93KgBike

20 years ago, you could buy a top of the line Triumph sport bike for less than what you 'd spend for a top of the line Trek, today.

It's not a Triumph and not the top of the line, but the MSRP on this Supersport is $12,995....

[pasadena]

I give credit to SRAM for putting some thought into making their 12 spd actually different than 11 spd. instead of just adding another cog.

I take away credit for integrating the powermeter into the chainrings, making them throw away items.

I'll be interested to see what Force AXS wireless looks like in April.

[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.

[oldpotatoe]

Originally Posted by 93KgBike

Well, GM Finance is worth several times what GM is worth. I guess the big bike groups are trying to get into finance.

20 years ago, you could buy a top of the line Triumph sport bike for less than what you 'd spend for a top of the line Trek, today.



Cool tech, however. *sighs*

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

[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...

[yinzerniner]

Originally Posted by Mark McM

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.

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.

[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?