But I want a 163.65 crank

see callin's comment. i think i'll hire him to cover this stuff from now on.

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Dan Empfield
aka Slowman

These spec options might be what you'll see on OEM bikes that hit the retail floor that have been spec'd with Force AXS. SRAM will usually list all their options, both OEM and AM (aftermarket) on the site, but that necessarily doesn't mean it's available for AM purchase. A good example of this is their RockShox line. Most AM forks are only offered in the RCT3 damper. The RC option you will see 80-90% of the time on spec'd bikes. Price is the name of the game in that world and it allows OEM's to have a good, better, best spec option for consumers and retailers. But maybe I'm wrong about this too. Just adding context as to maybe why...

So can someone explain why we need 12sp or why we need a 10 cog instead of adding an extra cog to reduce the gaps between the existing ones? I'd rather have better chain line.

Also... you don't need to have a 400W FTP to have a reason to use a 54 or 55 chain ring. Those that use 54 or 55s don't do it because so they can go 40mph on flats.

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What's your CdA?

Where is the 10-40/10-42 cassette option for 1x?!?! is the R. Der even compatible with that size?

I don't want an eagle r. derailer or 10-50 cassette for road/gravel

29-35 MPH on flats?

One thing that isn't clear to me is the clearance of the FD for larger tires. I currently can't fit anything larger than 700x38 on the "old" etap, and I've read they have addressed this with AXS using a slimmer FD design. So, is this a slimmer battery or FD to get more clearance with AXS. Is the AXS battery the same as the old one? I know they are compatible between the old and new etap, based on reading about the battery, but what I can't gleam is if the size and shape of the battery is the same. Got any info on this Dan? thanks!

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55x11@100rpm = 39.1mph

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What's your CdA?

We need 12 speed for the same reason we needed 11 when 10 was the norm, why we needed 10 when 9 was the norm, etc.




Sigh, it's a "chicken or egg?" situation. You need a 10T cog because you have smaller chainwheels. Or you don't need big chainwheels because you have a 10T cog. Pick your reason.

And even though you have to choose a smaller rear cog to get the same cruising gear ratio because of the smaller chainwheel, your chainline isn't all that different from where it was with 11-speed because the 10T cog is where the 11T cog was before, the 11T cog roughly where the 12T was before, the 12T roughly where the 13T was before, etc, etc, etc. If you "cruised" in a 54/16 before, you'll be in a 50/15 now and the difference in lateral chain deflection will be no more than 1/2 the cog pitch.

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"They're made of latex, not nitroglycerin"

1. 12sp: i asked why we needed 6, when 6sp came out. i stopped asking after 10sp.
2. 10t: range. it's a math exercise.
3. the width of the cassette is basically the same. so, chain line is unaffected.

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Dan Empfield
aka Slowman

Oh, most TTers with the big rings don't use the 11 for the bulk of the TT. The big ring is so they can use a more efficient cog.

If you have another use-case for very large rings other than flattish TT, track pursuit, or track sprinting, let us know!

You could do that with the old system. Nick at TriRig came up with the very slick setup pictured below. I mocked it up for myself and it indeed works well especially if you put a bit of skateboard tape over one of the buttons.

i believe i have both FDs here, old and new. let me check, and do some measuring.

now, on that subject, part of the problem is frame design. i'm riding exactly what you are: 700x38mm. and on old eTap. my chain stays are 425mm. i don't see eye to eye with every bike maker on this, but, here's my approach to gravel geometry:

1. start with road geometry.
2. figure out every way that a 38mm tire on a 700c wheel impacts something, and normalize for it.
3. ask yourself what you now need to change.

in other words, the larger wheel radius (353mm instead of 336mm or so?) impacts trail. shoe overlap. it raises the bike, so, you've got to correspondingly lower the BB from the wheelbase line from, say, 70mm to 85mm. you add chainstay because the operative metric becomes the leading edge of the inflated tire behind the seat post. you also change the bike's design to account for clearance in the Y and Z axes (front axle to the fork crown, the width of the fork blades, the width of the chain stays.

now, as a frame designer, you ask yourself if all that comports with the use case. no, you might say, you want a higher BB. okay. i don't, but i respect that you might. maybe you don't want road geometry, road contact points. okay. why? let's arm wrestle it out.

the point is, if you did what i suggest you do, as a bike maker, and eTap FD batteries don't hit the leading edge of an inflated road bike tire in 25mm, there's no reason why they should hit a gravel tire.

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Dan Empfield
aka Slowman

SRAM is claiming that the new chain is equivalent in efficiency to 11-speed chains. So if that's the case the old Friction Facts data should still be pretty valid. We're talking about the order of a full Watt vs 11T @300W. Possibly more. And 11T to 14T is another 1.5-2W. 14T appears be about the cog where efficiency gains pretty much disappear. So the jump from 14T to 10T is around 3W. I think that's fine for most purposes.

But a specialist in track or TT would want to use at least a 14T cog, then pick a ring that gets the ratio they want with that cog.

I'm not a big short-crank advocate (tried them for a couple years and switched back), but you aren't actually giving up anything definitive. Or probably gaining anything either! Aero and power were both a wash for me. It's what "feels" better. In my case I seemed to prefer the greater range of motion with longer cranks, even though the hip angle is pretty tight.

My thought here, given that the new Force AXS cassette is a pinned variant and not a fully CNC variant like RED, it should be something that they could pull together if demand is there. SRAM is usually really good about creating these down the road. I could see this being something they release at Sea Otter or some other gravel event like BWR. Fingers crossed...

What is skateboard tape and why do you need it? I’m still playing around with either (1) Nick’s setup using the bottom half of a sram shifter; or (2) just attaching the blip box to a Garmin mount which is then attached to my extensions with those oval rings m. Initial impressions were that the second option was more comfortable for shifting .

From the Bike Rumor first ride review:

"I do think that for it to be a true contender for a gravel group lower gearing may be desired, but SRAM is coyly hinting at more mix and match 'Beyond Road' options later this summer."

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"They're made of latex, not nitroglycerin"

I think I read on Glory Cycles that AXS will only work with AXS so old blip boxes would not work with the AXS RD, but now I can't find the Q&A. Maybe you can confirm.

Let me ask about chainlines and other compatibility issues as this is now way beyond my knowledge. Are we able to use any old crankset and/or chainring with a 12 speed AXS set up (which we could with 11 speed)? For example, I have FSA Gossamer Crank with a Power2Max PM and Rotor Chainring designed for 1x use. Is there any reason those parts wouldn't be compatible if I wanted to use them with a 12 speed AXS RD, cassette and new blip box?

This really depends on your intended use of the bike. In my case, the bike is custom. I wanted road geo that fits fat tires - my geo consideration are a little more complicated than that, but that’s really the starting point that drove my design.

Now, to me, that bike has short chainstays - 415mm, low bb drop - 78mm, steepish HTA - 72.5, stack a bit higher than my road fit, and reach a tad shorter than my road fit, but reach is created around the use of a 90mm stem (instead of my typical 110mm I use on the road).

This produces a very capable fat tire road bike that utilizes 650x42-48 and 700x35-40, depending on the terrain I plan to ride. For my larger tire tires to fit I had a custom wire harness built so I can mount the FD etap battery in another location. It would be nice to not have to do that!

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Basically sandpaper with adhesive on the other side. Makes it easier to distinguish between the buttons.

I checked. No can shift w/new blip box. Getting rid of that feature helped them make it smaller.

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Dan Empfield
aka Slowman

Exactly... that was my point as the ST article said that no one needs anything larger than 53x11.
I would have preferred they kept the classic ring sizes 55/54/53/52/50 and instead of adding an extra 10 cog they could have filled gaps in the high/mid range. This just seems like changing stuff for the sake of changing stuff.

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What's your CdA?

Any word on backward compatibility?

I'm baffled (as was James Huang in his cyclingtips review) why SRAM didn't release something to fill the gap between the 10-33 and the 10-50 cassettes. I really thought AXS Force was going to yield a 10-37 or 10-39 to pair with their 48t 1x front ring.

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