The worlds most awesome triathlon bike (in my eyes) got an upgrade. From Sram etap 2x to the new Sram axs 1x with 50t front and 10-33 back. It is just awesome in every way. Light enough gearing for the uphills in Norseman and with heavy enough gears for the fast downhills. Weight is lower, aero is better and no front derailleur which can brake. So what is the issue?
I dont have any data on it, but how is the drivetrain resistance in the lightest gear (with the biggest chain-crossing) and in the smallest cogs? Most of the races I will stay probably 90 % in the 12,11 and 10t, and in Norseman I will do at least 20 % on the 33t.
After using a lot of money on the new Sram axs I wonder if I would actually be faster on a 1x with 56t front and convert it to a 2x when doing Norseman or hilly races.
Any thougts?
The data from Velonews is based on the Sram Force 1x and not the nex AXS, but a 4-5 watt increase in resistance on the smallest cogs, which is where I prefer to stay on flat courses is difficult to swallow.
While the image being a tad small in the forum this is the calculation of speed on a 56/42t - 11-28 setup vs 53/39 - 11-28 and 50 - 10-33. On a 56/42 - 11-28 I can stay far more time in the 17, 16 and 15t.
I must say that l am not a fan of 1x except for very limited situations like extremely flat courses. Which Norseman is not. There is no way l would consider a 1x set up on such a course.
Also, about aerodynamics, to the best of my knowledge, there is no public data available that definitively shows a significant aero advantage of 1x over 2x. Especially when a rider uses a mechanical (vs electric) FD.
And, for truly unbiased tests, any aero comparison between 1x and 2x has to consider the aero impact of, for a 1x set up, the much bigger cassette, plus the larger pulley mech, and any chain differences. And such a test should include an mechanical FD instead of only testing the aero impact of (typically huge) electic FDs. If such an aero comparison has been done, l have never seen the data.
Mathematically speaking looks like 1x is going to offer aero advantage in a flat course when you’re going fastest as you can and not cross chaining, but once the chain loss alignment the gains are killed with friction. But the perception and experience racing as pro might be different. What are you’re thoughts as I’m debating exactly on this to go 1x (lighter and looks cool ) or 2x (most efficient for all terrains)
The data from Velonews is based on the Sram Force 1x and not the nex AXS, but a 4-5 watt increase in resistance on the smallest cogs, which is where I prefer to stay on flat courses is difficult to swallow.
Without knowing the specifics of that test, there could be more variation than that just through the chain preparation process. Which, given each setup was using a different type of chain, could be a notable contributor to variation
While the image being a tad small in the forum this is the calculation of speed on a 56/42t - 11-28 setup vs 53/39 - 11-28 and 50 - 10-33. On a 56/42 - 11-28 I can stay far more time in the 17, 16 and 15t.
Now, let’s talk about efficiency. Lots of great math and analysis has been posted elsewhere, and different people come to different conclusions. Those who decry the 10-tooth cog complain that it comes at a cost of efficiency in the system, to the tune of a couple of Watts (I’ve read anywhere from 1 to 6 Watts lost compared to an 11-tooth cog). However, I find this an incomplete story. First of all, keep in mind that dropping the front derailleur and small chainring could (and in my testing, DOES) represent a wattage savings which can offset any mechanical loss by adding a 10-tooth cog. Moreover, that savings will be enjoyed throughout 100% of your ride, while the mechanical loss only applies while you are actually in the 10-tooth cog, which is maybe 10% of your ride or less, depending on route. So, that would suggest that the aero savings need be only 10% of the magnitude of the mechanical loss for them to offset one another. That is, even if a 10-tooth cog costs you 10 Watts (10 percent of the time), and dropping the front derailleur only saves you 1 Watt (all the time), those offset one another. I’m confident that in reality, the disparity is far less, meaning that there is, in the end, a net efficiency savings.
What about going smaller-toothed cogs? Is a 9-tooth cog worth the trouble (and additional loss in mechanical efficiency)? From where I’m sitting, with the available gearing, 9-tooth cogs are not a necessity. I think for the vast majority of athletes, 10-tooth cogs with the appropriate chainring will do just fine. But more important is the fact that 9t cogs can finally exist, thanks to SRAM’s innovation in this space. I predict that the 10t cog will reign supreme over 11t or 12t, regardless of the athlete. More important that the size of the smallest cog will be the size of the chainring, and the actual cassette range.
More than anything, I wonder how well does wax work on those 12 speed axs chains. Some people have trouble with it while others preferred it. I wonder if different wax formulations affect the chain with tighter tolerances?
Now, let’s talk about efficiency. Lots of great math and analysis has been posted elsewhere, and different people come to different conclusions. Those who decry the 10-tooth cog complain that it comes at a cost of efficiency in the system, to the tune of a couple of Watts (I’ve read anywhere from 1 to 6 Watts lost compared to an 11-tooth cog). However, I find this an incomplete story. First of all, keep in mind that dropping the front derailleur and small chainring could (and in my testing, DOES) represent a wattage savings which can offset any mechanical loss by adding a 10-tooth cog. Moreover, that savings will be enjoyed throughout 100% of your ride, while the mechanical loss only applies while you are actually in the 10-tooth cog, which is maybe 10% of your ride or less, depending on route. So, that would suggest that the aero savings need be only 10% of the magnitude of the mechanical loss for them to offset one another. That is, even if a 10-tooth cog costs you 10 Watts (10 percent of the time), and dropping the front derailleur only saves you 1 Watt (all the time), those offset one another. I’m confident that in reality, the disparity is far less, meaning that there is, in the end, a net efficiency savings.
What about going smaller-toothed cogs? Is a 9-tooth cog worth the trouble (and additional loss in mechanical efficiency)? From where I’m sitting, with the available gearing, 9-tooth cogs are not a necessity. I think for the vast majority of athletes, 10-tooth cogs with the appropriate chainring will do just fine. But more important is the fact that 9t cogs can finally exist, thanks to SRAM’s innovation in this space. I predict that the 10t cog will reign supreme over 11t or 12t, regardless of the athlete. More important that the size of the smallest cog will be the size of the chainring, and the actual cassette range.
More than anything, I wonder how well does wax work on those 12 speed axs chains. Some people have trouble with it while others preferred it. I wonder if different wax formulations affect the chain with tighter tolerances?
I have AXS (2X) and have waxed with molten speedwax, smooth as my standard etap. Anecdotal I know…
This is the thread where I saw people having trouble with wax axs. I wouldn’t know since I run di2 and have no problems with wax. On that 10t cog I presume getting a good waxing will be even more important.
Not to side-track the thread but I am interested in how those bars will work for you on a course like Norseman. They just look narrow and in combo with the stem and angle don’t look to provide the most stable platform when in the non-aero configuration. I get the idea in general but I would have thought a more traditional and stable steering position would be advantageous on technical courses.
Or, just get a AXS Front Derailleur and 2x chainrings for when you need 2x on specific courses (like Norseman)… When you don’t need it, change back to 1x. You don’t even need to change the RD / cassette.
Jim Manson did a wind tunnel test on 1x vs 2x. When looking at the -10 to 10 yaw range. The 1x savings was between 2 and 38 grams of drag depending on yaw angle. I believe that was done using the same cassette and rear derailleur in back so it’s unknown if a bigger cage and longer arm derailleur would have any effect
How much lighter is your SRAM AXS vs a 2x Di2 setup? Have the slightly larger gear jumps bothered you at all vs the 2x?
I love the look of 1x, and keep on thinking of going down that route but from a practicality standpoint I just don’t see a big benefit vs the downsides. But the nice thing about AXS as another poster mentioned, is you can buy an extra crank and a FD you can could change it to 2x for certain races if needed.
I recall a poster on ST had tunnel-tested a QR frame with 1x versus 2x, and found the 1x created more drag. I remember him speculating / attributing it to the ‘shift’ downtube configuration. I was always surprised by that finding - it seems like taking off that big hunk of FD would be categorically aerodynamically better.
You might have more luck finding the post than I did, but it was at least 2-3 years ago.
I recall a poster on ST had tunnel-tested a QR frame with 1x versus 2x, and found the 1x created more drag. I remember him speculating / attributing it to the ‘shift’ downtube configuration. I was always surprised by that finding - it seems like taking off that big hunk of FD would be categorically aerodynamically better.
You might have more luck finding the post than I did, but it was at least 2-3 years ago.
Mathematically speaking looks like 1x is going to offer aero advantage in a flat course when you’re going fastest as you can and not cross chaining, but once the chain loss alignment the gains are killed with friction. But the perception and experience racing as pro might be different. What are you’re thoughts as I’m debating exactly on this to go 1x (lighter and looks cool ) or 2x (most efficient for all terrains)
Yes, that were the image above is from, the root of my question stems from. But that is done on a Sram Force 1x and I dont know how transferable it is to the new AXS.
I must say that l am not a fan of 1x except for very limited situations like extremely flat courses. Which Norseman is not. There is no way l would consider a 1x set up on such a course.
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With a 48t front and 10-33 cassette it is nearly identical gear ratios as 53/39 and 11-28. I had no issues with the gear ratios in Norseman what so ever, it is just the potential resistance gain that worry me.
Not to side-track the thread but I am interested in how those bars will work for you on a course like Norseman. They just look narrow and in combo with the stem and angle don’t look to provide the most stable platform when in the non-aero configuration. I get the idea in general but I would have thought a more traditional and stable steering position would be advantageous on technical courses.
The Morf-Tech bars are made for Norseman Seriously, there is no faster solution. I did not manage 100km/h but 98,3
Jim Manson did a wind tunnel test on 1x vs 2x. When looking at the -10 to 10 yaw range. The 1x savings was between 2 and 38 grams of drag depending on yaw angle. I believe that was done using the same cassette and rear derailleur in back so it’s unknown if a bigger cage and longer arm derailleur would have any effect
How much lighter is your SRAM AXS vs a 2x Di2 setup? Have the slightly larger gear jumps bothered you at all vs the 2x?
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Thanks for the link. I guess it is both bike and angle depended. In Matt Hansons test the 1x was not faster, but I dont know what angle he did the test in and if that would make a difference.
I havent found the weight differences between the setups (tried googling it), but will find out. I loved the 1x in terms of gearing ratioes. I had no issue with bigger jumps, but also I am not very sensitive in regards of a “golden cadence”.
And, for truly unbiased tests, any aero comparison between 1x and 2x has to consider the aero impact of, for a 1x set up, the much bigger cassette, plus the larger pulley mech, and any chain differences. And such a test should include an mechanical FD instead of only testing the aero impact of (typically huge) electic FDs. If such an aero comparison has been done, l have never seen the data.
Why would a larger RD and different chain be needed for it to be unbiased? Not all 1x setups are AXS. I kept my mechanical RD9100 and DA chain. All I did for the change was change my 12-28 casette for a 11-32, removed the FD, and switched to an aero Rotor Flow 1x crankset from the 2x DA9000. Every 1x conversion looks different, so all of these tests are valid and useful as long as details are provided.
Speaking of chain and RD, though: the VeloNews test uses a PC-1170 chain on 1x vs CN-HG701 on the 2x. I can’t find the test anymore, but I remember the Shimano chain is faster than the SRAM chain, not sure by how much. The clutched Force 1 RD (per Diamondback) adds about 1w. It seems this test gave the 2x setup a few watts advantage right out of the gate.
In the Diamondback/CeramicSpeed report, which seems more controlled, there was only a friction disadvantage in the 4 smallest cogs and it was just 1w. When you’re blasting down a hill in a 10t, even 5w of frictional losses become almost meaningless compared to losses to RR and wind. Per bikecalculator.com, if I’m going 35mph then an additional 5w only adds 0.1mph. But 3w aero savings on the flats going 22mph, where I spend far more time, would net me 0.15 mph. So even in an extremely conservative case the 1x should be faster on most frames.
1x also allows the use of lower q-factor track cranksets.
I do wonder about the aero-ness of the AXS RD compared to 9100. It looks massive.
Seriously, there is no faster solution. I did not manage 100km/h but 98,3 