why don't we have actual data on Sram axs drivetrain efficiency?

[cajer]

Why more cross chaining?
Shimano and Campagnolo drive trains have 12 cogs on the same width cassette, yet, all the gear ratios for SRAM are larger (e.g. 50:10 > 53/54:11, 50:11 > 53/54:12, 50:12 > 53/54:13).
So at least in this end of the cassette, the SRAM 12s cassette is actually the one with the LEAST cross chaining at a given speed/ cadence.

People like to act like you need the 50:10 like all the time, when in reality 50:11 is already close to 55:12.

The chain is slow, that's the biggest weakness of SRAM 12s. Durable, but slow.
The small cogs are more inefficient, but probably less than people make it (as the 10t cog is rarely used, unless you undersize your CRs).
Crosschaining really should not be a factor here.

52/48 (standard shimano/sram big chainrings) is ~8% which is the gap which is about the difference between one cog in the cassette. So this means you need to be shifter one cog further to the right to acheive the same gear ratio meaning more cross chaining.

How?
There are 12 cogs on each, and the cogs are about equally spaced for about the same width (we are talking give or take 2mm in total over the whole cassette).
The FIRST COG on the Shimano is an 11, and on the SRAM its a 10. So you are "equally far to the right" with 54:11 as you are with 50:10.
The same goes for all subsequent pairs of gears (54:12 and 50:11, 54:13 and 50:12). The only difference is, that the SRAM gear is always larger (50:10 is 55:11). The same goes for the 48 and 52 (although the 48:12 and 52:13 are the same size), and 46 and 50 chainrings.
At least at the outmost cogs (10 and 11 for SRAM vs 11 and 12 for Shimano), SRAM offers the bigger gear, meaning you are likely to use it less frequently (say you would shift from 50:11 to 50:10 on a SRAM at 95 RPM, then you are already going 55.5kph when you need to shift into 50:10).

So I stand by what I said: LESS CROSSCHAINING at the high end on SRAM for any given speed or cadence.

Sorry I forgot that the 10t basically acts as a spacer pushing everything one cog inboard. However most AXS setups still have a smaller chainring and rear cog combo inaddition to a lossier chain

[KarlGLS]

Any input regarding the new SRAM red (2024) ? I reckon larger pulleys would reduce friction and bring it close to Shimano efficiency


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[FlatlandClimber]

Don't think so. The larger pulley will have some minimal effect. Probably the main reason why OSPWs are a little faster is actually that they allow for lower tension settings.
The SRAM Flat Top chain, at least as far as I understand it, is not majorly changed in its construction and therefore should be just as slow as the previous chain (~1% slower than Shimano XTR).

[cleanneon98]

Is there any data on SRAM vs Shimano aerodynamics? I've been curious since SRAM derailleurs are a bit chunkier, especially the rear one.

[OtterSpace]

E1 is likely a wash compared to D1. Larger pulley wheels give it someting like a 0.5w or less advantage from less chain articulation well within testing error margins. E1 chain is likely less stiff from the cutouts that dropped weight and I've seen at least one complaint about E1 chain noise being worse buts is very early days for E1. Unfortunately, it will take ages to get E1 chain efficiency data from ZFC and cermaic speed. This stuff is minor in the grand scheme of things.

The bigger items for SRAM vs Shimano are losses in SRAM from smaller chainrings, SRAM chains are in general slower but very durable, and chain losses that a clutch can mitigate.

The chainring thing is what it is and isnt worth beating to death and can be mittigated by using bigger rings with SRAM.

On the chain side for SRAM you had to run a SRAM flattop chain with no targeted aftermarket options. YBN recently launched a flat top chain SLA-MK120 which initially seems to have 70% less chain losses (said at 16:42). However, testing is ongoing and will take awhile. The YBN chain certainly is less durable the question is to what degree and what is shifting like. This is huge compared to E1 vs D1 efficiency differences.

For clutches I think even the very geeky side of the market is sleeping on the advantage of SRAM's road fuild damper clutch (Orbit) over Shimano's lack of any clutch for road. Also the Shimano mechanical spring clutches used in GRX are worse and kind of antiquated compared to SRAM. Even on very smooth roads the bottom portion of a Shimano chain will bounce on RD-R9250 which is easy to see when watching road racing. For me this is more of a shiting smoothness and safety thing but there definately is an efficiency impact too. With a good clutch you can run lighter spring tension too which aids efficiency.

https://youtu.be/z7TdWbjwzi0?t=226
https://velo.outsideonline.com/road/roa ... -friction/

With that said its very hard to make a lab setup that accurately captures and imparts representative road oscilations to test clutches for efficiency. In general the faster you are going and the rougher the road the more losses you will have without a clutch.

[cajer]

E1 is likely a wash compared to D1. Larger pulley wheels give it someting like a 0.5w or less advantage from less chain articulation well within testing error margins. E1 chain is likely less stiff from the cutouts that dropped weight and I've seen at least one complaint about E1 chain noise being worse buts is very early days for E1. Unfortunately, it will take ages to get E1 chain efficiency data from ZFC and cermaic speed. This stuff is minor in the grand scheme of things.

The bigger items for SRAM vs Shimano are losses in SRAM from smaller chainrings, SRAM chains are in general slower but very durable, and chain losses that a clutch can mitigate.

The chainring thing is what it is and isnt worth beating to death and can be mittigated by using bigger rings with SRAM.

On the chain side for SRAM you had to run a SRAM flattop chain with no targeted aftermarket options. YBN recently launched a flat top chain SLA-MK120 which initially seems to have 70% less chain losses (said at 16:42). However, testing is ongoing and will take awhile. The YBN chain certainly is less durable the question is to what degree and what is shifting like. This is huge compared to E1 vs D1 efficiency differences.

For clutches I think even the very geeky side of the market is sleeping on the advantage of SRAM's road fuild damper clutch (Orbit) over Shimano's lack of any clutch for road. Also the Shimano mechanical spring clutches used in GRX are worse and kind of antiquated compared to SRAM. Even on very smooth roads the bottom portion of a Shimano chain will bounce on RD-R9250 which is easy to see when watching road racing. For me this is more of a shiting smoothness and safety thing but there definately is an efficiency impact too. With a good clutch you can run lighter spring tension too which aids efficiency.

https://youtu.be/z7TdWbjwzi0?t=226
https://velo.outsideonline.com/road/roa ... -friction/

With that said its very hard to make a lab setup that accurately captures and imparts representative road oscilations to test clutches for efficiency. In general the faster you are going and the rougher the road the more losses you will have without a clutch.

If you had to estimate how much loss do you think there is between the clutchless shimano vs sram with a clutch on the road? Also don't sram derailluers generally run higher tensions, so you'd get more losses anyways?

With this in mind, on clutchless systems wouldn't it make sense to run a higher derailluer tension to reduce bouncing too?

[OtterSpace]

If you had to estimate how much loss do you think there is between the clutchless shimano vs sram with a clutch on the road? Also don't sram derailluers generally run higher tensions, so you'd get more losses anyways?

With this in mind, on clutchless systems wouldn't it make sense to run a higher derailluer tension to reduce bouncing too?

Key word being estimate given this is a compete guess on my part with no data...

I would guess at pro speeds something like 1-10w with the lower losses being relatively smooth pavement and the larger losses descending on cobbles.

The bigger issue is without a clutch it is very easy for a pro to drop a Shimano chain off the outside of the big ring from this lower chain bounce when they go from high power to 0 rider power which can be very dangerous especially when descending.

Here are two examples of such chain drops.
https://www.youtube.com/watch?v=KV51udbBj-w&t=592s
https://youtu.be/9Wi1pSLNV8c?t=343

This should go without saying but a dropped chain is a total efficiency loss.

To me this is one of the two biggest issues I want Shimano to address in their next high end groupset launch.

[cajer]

Ough I didn't even think about that. Though 1x with a narrow wide chain ring should help with that.

It makes me almost want to go with a sram groupset and classified hub which would get around the sram front derailluer shifiting. However I can't get around the chain losses + the useless 10t gear. Also the general shifting performance and braking is also worse on sram. Though I imagine there are third party cassettes that end at 11t.

Does the new TRP/classified groupset have a clutch? But the through axle likley loses a good bit of the aero gain from no front derailluer.

[Nickldn]

It makes me almost want to go with a sram groupset and classified hub which would get around the sram front derailluer shifiting. However I can't get around the chain losses + the useless 10t gear. Also the general shifting performance and braking is also worse on sram. Though I imagine there are third party cassettes that end at 11t.

Look, if you really believe the story that SRAM FD shifting is so bad compared to Shimano that you'd go to the expense of a Classified hub then you have really fallen for Shimano marketing and fanboy comments on this forum. Yes, there is a small difference, but both are easily good enough for most normal riders. Same applies to general shifting of the RD. As for the 10t cog, if you were climbing in that gear then losses compred to 11t might be measurable, but you're not are you?

There is a lot of perception driven by marketing in the industry and a few fanboys, don't fall for it.

I have used all three big manufacturers' systems and Red D1 has no real weakness in shifting, but on the other hand the RD clutch is a great addition and really lacking in Campy/Shimano.

[wheelsONfire]

If quiet = smooth = fast… SRAM AXS fails miserably. I have been so much happier being back on Campy or Shimano 11 spd. Even ETap 11 is a relief.


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Have had Etap and AXS and saying 11 speed is so much better is pure BS. Sram coud be compared to mechanical and it's faster, even 11 speed Etap shifting was and AXS is a bit faster.
If you have problem with noise you must have done something wrong, i have been on Sram since 2015 and keep it clean and lubed and there's no noise.
I would pick Sram 8 days a week over Shimano and yes, i do have Shimano on one bike.

[wheelsONfire]

It makes me almost want to go with a sram groupset and classified hub which would get around the sram front derailluer shifiting. However I can't get around the chain losses + the useless 10t gear. Also the general shifting performance and braking is also worse on sram. Though I imagine there are third party cassettes that end at 11t.

Look, if you really believe the story that SRAM FD shifting is so bad compared to Shimano that you'd go to the expense of a Classified hub then you have really fallen for Shimano marketing and fanboy comments on this forum. Yes, there is a small difference, but both are easily good enough for most normal riders. Same applies to general shifting of the RD. As for the 10t cog, if you were climbing in that gear then losses compred to 11t might be measurable, but you're not are you?

There is a lot of perception driven by marketing in the industry and a few fanboys, don't fall for it.

I have used all three big manufacturers' systems and Red D1 has no real weakness in shifting, but on the other hand the RD clutch is a great addition and really lacking in Campy/Shimano.

To to be honest, i wonder if people here just mouth off and if they actually have had Sram and so much problems, they must have terrible mechanical skills.
If someone should mouth off about AXS they should have experience with it. I was also in the belief that 10t cog would be such an issue, but to be honest, my AXS drivetrain is way better than i thought. All assumptions based on theories i read at the net of 48/35 and a 10t cassette cog, it was all out the window once i just set it up and rode it.
I ride 6-7 days a week this season and i have no complains about the AXS (RED) and it's the previous version. It's so much BS about Sram.
The only groupset i have had issues with talking electronic, is my Di2. Also the hydraulics is a problem.
Talking Sram Etap and AXS i have the rim brake version with EE brakes and i have had no issues with none of these two.
Excellent performers. I clean my bike very very often and no issues with moist or the circuits talking in water.
Keep the drivetrain clean and it's fast and have a low noise level. Shifting is great and have always been.

[cajer]

It makes me almost want to go with a sram groupset and classified hub which would get around the sram front derailluer shifiting. However I can't get around the chain losses + the useless 10t gear. Also the general shifting performance and braking is also worse on sram. Though I imagine there are third party cassettes that end at 11t.

Look, if you really believe the story that SRAM FD shifting is so bad compared to Shimano that you'd go to the expense of a Classified hub then you have really fallen for Shimano marketing and fanboy comments on this forum. Yes, there is a small difference, but both are easily good enough for most normal riders. Same applies to general shifting of the RD. As for the 10t cog, if you were climbing in that gear then losses compred to 11t might be measurable, but you're not are you?

There is a lot of perception driven by marketing in the industry and a few fanboys, don't fall for it.

I have used all three big manufacturers' systems and Red D1 has no real weakness in shifting, but on the other hand the RD clutch is a great addition and really lacking in Campy/Shimano.

The idea behind going classified is that I would also be able to drop FD and inner chainring and also use an aero crank, while at the same time getting rid of the worse FD shifting with sram. If I'm going to go 12s (currently on shimano 11) I would want something where I'm not taking large losses on one of the gears when I ocasionally have to use it. Also if I do end up using the 48/34? combo, I'm also running a smaller cog (than with a 52 chainring) in the rear which is some more marginal loss. Yes it's all of these things aren't large, but I have fun opitimizing the bike.

I think with the new YBN chain, classified hub (ideally they come out with a flush through axle), larger (not 48t) big ring, and 11t small cog the sram setup would be very good.

[OtterSpace]

The the classified system is good for what it is. However, at a high level I currently would avoid it for road.

I mostly have worked at start up companies trying to get sold to a bigger fish and I would say as a complete outsider that classified are close to a sale if that is what they want. If you are positioning a company for a sale you want to make it look like you dont need the bigger fish and can go wide to up your evaluation. However, what really matters is the core technology which needs the big fish to really bring it to wide adoption with their larger pool of patents, resources, and established market base.

More specifically with 12s chains, cassettes, and chainrings became more of an ecosystem than before and tolerances increased due to fitting more in the same hub width. Also since STI levers launched the market wants integrated braking and shifting. These things together make aftermarket shifting parts kind of a bodge for performance 12s road. The same goes for aftermarket cassettes while they work they compromise shifting performance. Even the fast chains generally shift worse.

As a Shimano user the 10t thing is mostly a red herring. In general SRAM allows wider rear ratios with smaller front ratios which they default position for a super bailout gear by using smaller front rings. If you are worried about efficiency get bigger front rings and consider the 10t a dont spin out gear and all is good.

[toxin]

I just can't understand 13t front jump instead of 16. I see zero drawback with 50-34 instead of 46-33 (the tiny 1 tooth difference I guess). In fact I wouldn't mind using that at all with a 10t cog as an overdrive for descends where I really don't care if I'm losing 5 watts.

[OtterSpace]

I just can't understand 13t front jump instead of 16. I see zero drawback with 50-34 instead of 46-34.

This the better way to articulate Shimano's FD advantage than the typical chain drop discussions.

Many run 52-34 no problem on Shimano for a 18t drop while SRAM's chainring drops are all 13t for E1.

I've seen speculation that there are some patents limiting SRAM and its good to see them get some auto trim on E1 but I think from memory its two positions vs 5 for Shimano. (edit: confrimed 3 tims on big ring 5 on little ring)